Dual Motor AWD Electric Bikes – Case Study: Fat Trail and Hill Climber

Built to conquer the weakness of twin hubs in hills – and eliminate the damage a mid drive does to an ebike’s drivetrain. The bike I call 2Fat did all that.

AWD Ebikes Menu
AWD. OMG. WTF!
Case Study – Flatland Fat Bike Commuter. Hub+Hub
Case Study – Alpine Road & Trail. Hub+Mid Drive (you are here)
Case Study – Low-Power Cargo Beast. Hub+Mid Drive

So, my Gen 1, 1.5 and 3 bike layouts are all twin geared hub designs. What was Gen 2?

2Fat

  • 750w, 35a geared Bafang G060 front hub motor
  • 30a BBSHD mid drive
  • 52v, 12.5ah rear motor battery in triangle
  • 52v, 12.5ah front motor battery on rack top
  • Batteries connected in parallel to form a single ‘virtual’ 25ah power source to both motors
  • KT and Bafang displays
  • 160Nm rear… 80 Nm front (do the math on that one!)

I live part-time in two towns: The first, an extended work visa, is in Fresno California, smack in the middle of California’s San Joaquin Valley and flat as a table. I built The Colonel, The Purple Thing and The Great Pumpkin for commuting in Fresno.

While I most often take pics of it in a wooded area, 2Fat is just as happy on paved, hilly roads. Shown here with front panniers, its 4-bag carry capacity makes it a quasi-cargo bike.

After a fashion, I finally was able to get a big enough bike rack on the back of my SUV to bring the Colonel to my actual home in Pacific Grove, California. My house is at the top of the hill there. Unlike in Fresno, nothing in or around the area is flat. You are either going up a steep hill, or down one, or both.

My intention was to be able to use the Colonel like I did in Fresno, as local errand transport and a light duty cargo-shopper. Unfortunately, I found out the first day about the limitations of hub drives: They suck in hills.

Hubs are Single Speed

Hub drives power an ebike via the axle. They don’t – and they can’t – use the gears of the bike. Forcing a single speed hub motor up a hill makes it just as miserable as a human stuck with no gears. So even though I have very powerful hubs, and they were geared hubs that put down the most torque of any on the market… they still struggled. Even with two of them. I could hear the gears groaning inside the motor casings and I could tell that, while I could get up the hills, my motors were not happy about it. I did not want to lug them into an early grave. I had already gone to a lot of trouble to make the bike bulletproof and had no desire to ignore the problem and inevitably kill it.

These twin 80Nm hub motor wheels were on The Colonel at the time of my first hill country ride (above). Now they are on the Great Pumpkin.

The solution?

I Need To Build a New Bike

Everybody knows mid drives are the solution to the hill problem for an ebike. A hub motor is single speed and at least relatively weak on torque, but a mid drive uses the gears in the drivetrain, plus it has double or more the torque output of a hub, and thats before you factor in the multiplier of the gears. Wonderful right? Except mid drive motors – especially DIY builds – are notorious for putting drivetrains into an early grave. Why? Well because they pour a LOT more power through the chainring, chain, rear cluster and cassette body (i.e. “the drivetrain”) than a bicycle was ever meant to withstand.

  • A normal cyclist can pump out maybe 300 watts for a minute or so, but typically normal sustained – strong – output is about 100 watts.
  • A professional sprinter/mutant is capable of pumping out almost 1000 watts, but only for about a minute or two. Thats not enough power to make a slice of toast.
  • EU-market electric motors must peak at 250w of output to stay legal (pssst… they don’t).
  • A 25-amp BBS02 on a 48v system puts out in excess of 1250 watts peak
  • Your garden variety 30-amp BBSHD running under a 52v battery is peaking – and can sustain – about 1750 watts of output.
My rear rack trunk battery. The capped red wire is for charging. The black wire on the rack stay is power output to the front motor. This is the original dual-separate-battery config

That gives some perspective on how much abuse is heaped upon a drivetrain with a mid drive. Coming off the successful builds of The Colonel (v1.0) and the Purple Thing (v1.5), I knew AWD reduced load on the individual motors dramatically when they work together as a team.

Given that, I thought about how I could use a front hub to reduce or eliminate the shock that a mid-drive puts onto the ebike’s drivetrain. Not only would I gain the traction benefits of AWD, and the benefit of reduced load from the team effort – things I already knew were a big positive – the front hub would also, if used in a slightly different way, provide an important added benefit: eliminating all the extra wear and tear that goes with having a mid drive.

If it worked, it would give me a bike with all the original AWD performance benefits, plus the ability to effortlessly climb walls, without tearing the bike up.

SPOILER ALERT: It worked unbelievably well.

New steel on the right, used alloy (1000 miles of use) on the left. And this was WITH AWD to reduce the wear and tear. Ordinary single-motor systems with this mileage would be dramatically worse. Substituting the steel body eliminates all wear.

In fact this bike is a showcase on how AWD can almost eliminate mid-drive wear and tear. Making a bike that climbs hills and bombs trails really well is almost an afterthought.

So that is what I am going to focus on here in this article. What was built and how was it used?

The Build

Briefly, this bike is the Great Pumpkin on the front wheel, and a typical mid-drive installation on the back. In between is the usual extra wiring scattered all over the place to deal with powering two motors, set up dual PAS etc..

The Front Motor

2Fat has another Bafang G060 80Nm front fat motor installed – this time its inside of a custom-built 100mm double-wall Weinmann (branded as an Origin8) rim. Go fat or go home. Attached are the same two torque arms as seen on the Pumpkin’s installation, and once again the controller is sitting in a grommeted handlebar bag that doubles as a wallet/keys/phone holder. It also serves to disguise the uncut steering tube I used to give me a more upright – but not too upright – riding position.

Another big, fat, 80Nm front hub motor. This time laced into a 100mm rim. Because fat bike.

Different from the Pumpkin is the battery setup. This bike was built before the v3.0 Pumpkin came onto this Earth (The Purple Thing had just been born). So, lacking the wherewithal to commission a big custom battery for the triangle, I used two packs, one for each motor. The front motor’s 12ah 52v battery was located in the rack trunk at the back of the bike. I had already learned I did not want to put a battery on the front rack as it made the steering too heavy. The rear motor’s 17.5ah pack was in the triangle.

It could be worse: Tucked in between the panniers in the rack trunk is one of two batteries. The second pack is in the triangle. Whats on the front rack? A weatherproof, adjustable 5a charger.

Additionally, due to the very low standover of 2Fat’s Large sized frame thanks to its top tube (it is a titanium, USA-made Chumba Ursa Major) there is not enough room to plug in a properly big battery in the triangle to handle both motors. So I had to do two batteries and live with the awful choice of putting one on the back rack.

After running the two dissimilar, separate batteries from its initial build in 2017 to March 2021, I switched to two identical, now-parallel’d-together packs in the same locations. Each is 12.5ah (14S6P) with Samsung 25R cells. Each has a 50a continuous BMS. As such, the system has a single 25ah power supply with a BMS capable of handling 100 continuous amps. Considering I can never peak past 65, I’m in great shape. I purchased the packs from Bicycle Motorworks, who builds their packs in the USA and constructs them at time of order.

Sidebar:  
Running battery packs in parallel should only be done by those who have done the research and know exactly what they are getting into.  In this case, both packs are identical, being manufactured to-order together, and have the same charge cycle count.  Their voltages were matched before they were joined and there is some additional babysitting that will be necessary for charging and balancing.  If you can avoid running packs in parallel and use just one battery: Do that instead.  

Using two entirely separate batteries is a kludge and your last resort. Not only will you have to charge them separately, you will also draw down the two batteries separately at different rates which will result in uneven remaining power, lesser range and more frequent recharges.

The Rear Motor

This is pretty much your garden-variety 52v BBSHD installation. It has a couple of nice spiffs in the form of a 42T Lekkie Bling Ring, and Lekkie Buzz Bars, but neither of those things are a requirement of the AWD approach we’re discussing here.

The rear wheel is another matching Weinmann 100mm rim, again with DT Champion 2.0 spokes and 16mm brass nipples. The rear hub is a DT 350 Big Ride, which has sealed cartridge bearings and has been upgraded to a steel cassette body. Additionally a 9-speed Shimano HG400 cluster gives me steel cogs literally welded together into a single cluster, that spreads the enormous torque of the BBSHD across the entire steel cassette body. The DT350’s ratchet engagement mechanism is one of the few known bombproof rear hub mechanisms when faced with the power of the Dark Side 30a BBSHD motor.

A solid rear wheel build with extra strength parts throughout is crucial to a successful mid drive ebike.

205mm front and rear rotors with Magura MT5e brakes

The Special Bits

There is a bit more that went into making these motors work together. The complete integration possible on the Pumpkin thanks to the use of identical motors and controllers wouldn’t work here.

Brake Cutoffs

Trying to share cutoff signals between the motors again – using adapters for the red-to-yellow connections found on the BBSHD – resulted in bricking both motors. I tried everything to share the signals. It can’t be done unless you are willing to install a second, independent set of hydraulic magnet style cutoffs, zip tied to the integrated MT5e cutoffs and connected via a ‘y’ further down the line. That would work but it would look like crap, for very little benefit over what I ended up doing: I set up the front brake to engage the front motor cutoff, and the rear – with a red-to-yellow HIGO adapter – to cut off the rear motor. Since I always use both levers to do my braking I get an effective result.

Pedal Assist

PAS for the BBSHD is built into its motor casing, so it just works. PAS for the front motor was another matter entirely. Ordinarily the assist disc and sensor runs on the right-hand, drive side of the bike and hides behind the front chainring. This is not possible with the BBSHD’s secondary gear housing being there instead. So PAS had to be made to work on the left hand side. The KT controller has left-hand PAS sensor installation settings.

What was needed then was a left-hand install. This was quite a bit trickier, since the 120mm motor running in front of 5″ tire-compatible chainstays had zero extra spindle length to mount the disk. Lacking a bottom bracket cup to mount the PAS sensor ring, I set it behind a second inner lockring – I used two inner lock rings stacked like jam nuts rather than the usual inner+outer ring. These doubled inner rings had the secondary benefit of being a more aggressive, solid mounting for the motor.

With the sensor mounted, next I had the sensor ring to deal with. As noted above… there was no length available period for the sensor disk as the crankarms mounted pretty much flush to the bottom bracket.

The eventual solution involved hogging out the center of the PAS sensor disc so it could sit on the inner flange of the Lekkie crankarm instead of the spindle. I prepped the crankarm with… thin strips of thick duct tape so the disk would sit tightly on the flange. It was a bodge but it worked, and with just one improvement since installation in 2017 it has held perfectly. That improvement is a zip tie to help hold the disk steady in position (of course I used a zip tie. We have duct tape in the mix; all thats missing is a zip tie).

Worth noting: I used this identical PAS ring mounting when I built the Lizzard King AWD cargo bike in 2021. Not only did I have enough extra spindle so I did not have to do this surgery on the ring, I also realized I could unscrew and reverse the sensor in its mounting ring. This eliminated the need to use the reverse settings in the display/controller. Since the inset ring was reversed, it was outset now… and that held the sensor closer to the magnets (they work fine inset as seen here, but closer is better).

The Cockpit

Here’s where the eagle-eyed may spot a preview of how I ride this bike to soften up the mid drive.

Those are Jones SG bars with ESI XL Extra Chunky grips, wrapped in silicone tape

On the right, we have the grip, then the brake lever, followed by the 9-speed shifter. Here again we see a v2.0 feature that v3.0 fixed: A SRAM drivetrain gives us a SRAM, not Shimano shifter. The Shimano shifter needs so much real estate on the grip it is impossible to put a throttle on that side of the handlebars. Look at the cockpit of The Great Pumpkin and the Lizzard King to see how a SRAM shifter solves this and lets me do one throttle per thumb.

Being unable to do that at the time – and believe me I tried EVERY possible combination of throttles. I still have most of them in a box in my garage. I settled on two styles of thumb throttle, side by side on the left, with the innermost throttle being for the hub/front and the outermost for the BBSHD/rear. As for the eagle-eyed part: The front throttle is cocked higher so between that and its longer throw, it is engaged first and when at 100% it follows the natural curve of my thumb. Both throttles can then be at 100% and my hand stays comfortable at WFO.

How To Ride It

At last we get to the point!

I already let the cat out of the bag earlier: The biggest deal associated with this bike is not that it can climb really well (REALLY well). Nor is its ability to handle trails and rotten conditions its star quality.

2Fat was made to get dirty

No, the real point of having a mid drive teamed with a front hub motor is to use that hub motor to take the shock off the drivetrain that mid drives deliver. Do that and you also take away the excess wear and tear on the parts (if we are being fair, a lot of this comes from doofus riders who don’t know what they are doing).

When starting, start with the hub

This is most of the deal right here. Don’t make the mid drive haul the bike up from a dead stop. Its got the torque to do it. But everything takes a beating in the process. The nylon gears inside of the mid drive. The chainring. The poor chain. The suffering cogs. The cassette body being dug into by the cogs. The pawls inside of the cassette body that are straining against the hub. Your ebike hates you for doing this to it.

By using a mid-drive-strong chain, a steel cluster and a steel cassette body with a ratchet engagement mechanism, we harden the drivetrain to be very tolerant of this abuse. Between that and learning how to use a mid drive, wear and tear really isn’t bad at all. Maybe no worse than a quality analog bike used hard. But still… even with the hardened drivetrain it sure would be nice to take things easier.

By using a hub motor to get the bike rolling – even by just a few mph – we accomplish this mission. Using my pedaling-friendly BBSHD programming or something like it, the BBSHD will not kick in on pedaling until the bike crosses about 5 mph. So from a stop, you hit the front throttle for about one full second. That throttle is cocked up a bit higher on 2Fat to make that a natural move. The bike starts up from its dead stop without any strain on the drivetrain since the BBSHD is not even running. Simultaneously, you also start pedaling. This engages the cassette mechanism.

When speed crosses 5 mph, the BBSHD’s pedal assist now kicks in on a drivetrain that is already engaged. There is no longer a risk of having the motor jerk the chain and smash the cluster into engagement. And with this gentle engagement, the motor starts working on a bike that is already moving. So you get the doubled benefit of a lighter effort against all components to get your fat bike off its fat ass. Instead, you get smooth – and strong – acceleration. The lack of lugging the motor has the further benefit of not generating anywhere near as much heat since the motor is no longer running at low rpms for anywhere near as long. And those nylon gears inside the motor are writing you a nice thank-you card.

Or…

Rather than using the throttle, you could also just start pedaling. I have set the KT controller to engage PAS as quickly as possible. Combine that with the BBSHD’s controller being told to hang back for the initial startup, and you have a completely thumbs-off solution that implements at a nice gentle pace.

So… It just works.

Or you can force it! Remember with this setup you have two throttles. There’s no law that says if you need it, you can’t jump the gun and either hit the rear throttle early, or hit it so the motor engages harder than it would have in your designated PAS mode. So if you need a little extra push thanks to an XL load of groceries, or a steep hill, you have options at your disposal.

Downshift? Schmownshift!

One of the mantras associated with smart mid drive riding is that you always Always ALWAYS freaking downshift the bike when you come to a stop. The LAST thing you want is to lug the motor up from a dead stop because of all the brutality it visits on your chain, your cogs blah blah blah. So that means you remember to downshift one or two… maybe even three times before you come to a stop. When the light turns green you upshift in sequence one gear at a time as you get back up to speed again. Thus as we all understand: you row thru the gears.

Another rule mid drive mavens repeat ad nauseum is – if you have an 11T small rear cog… stay the hell off of it. Its too small to use on a mid drive. It bogs the bejesus out of the motor from a stop, its too small to be able to get up to speed before the sun sets and if thats not bad enough, the teeny cog on even the steel Shimano clusters is alloy and it is not attached like all the others are. Its an individual. So not only do they dig into the cassette body harder, they die fast. Like Really Fast. As in a few hundred miles tops.

Well, on AWD mid drives like 2Fat, you can forget about all that. Because of the powered front hub doing its part (either thru a quick dab of throttle or just letting PAS start the bike), there is no longer a need to shift at a light. You can forget about the whole process. Just leave it and it’ll be fine as if it was a hub motor! In fact the front motor allows the bike to increase its speed so it gets up and goes fast just like a hub motor does.

I found this out within a day of building the bike, and since then learned from experience the 11T cog will last about 1500 miles before it typically cracks (two so far). Thats not so bad for a readily available US$7 part. And if I wanted it to live longer, well it wouldn’t kill me to go up a gear at a light once in a while.

At the office, outside my e-garage. There is a trail network along my commute route that 2Fat lets me take

Wrapping It All Up

2Fat itself is not the ideal example of how to execute this concept. It is a product of when it was built and my knowledge level at that time. In the present day, I for sure would not want to build a bike with two batteries, and if I did I would NEVER put one on the back rack. But thats partly the limits of the frame I used. I came within a hair of using a Salsa Blackborow frame kit for this bike until, at the last minute, this titanium beauty fell into my lap for a song… but thats another story.

Next, I wouldn’t use Shimano components thanks to the real estate problems introduced by the shifter. Instead I’d use SRAM components so I could do one throttle per thumb.

Really the Great Pumpkin with its XL size and XL triangle, plus its SRAM shifters – would be ideal here. But them’s the breaks. This is what I’ve got. Boo hoo.

With that said… I did learn as I went along, and in 2021 I returned to dual motor bikes with the Lizzard King, a bike meant to prove a different kind of AWD could be awesome: You don’t need the 80Nm, 35a punch of the Pumpkin’s or 2Fat’s front hub to gain the benefits of AWD. A low power implementation, done a little differently, should be very effective and appeal to a much broader range of everyday, low-speed, low-drama ebike use. And…

SPOILER ALERT: It worked unbelievably well.

BBS02 and BBSHD: Do I want a gear sensor?

This is a common question on BBSHD and BBS02 motors, so I thought I would write up a quick post and describe what can be done, and what I do.

Here’s The Problem

If you shift under power with a BBS02 or BBSHD, you will do so using a LOT more power than your ebike’s drivetrain (chainring, cogs and chain) was ever designed to handle. Shifting while under even a moderate amount of power is a great way to snap your chain and take the Walk Of Shame home. Worse: you can crack or even taco a cog.

Here’s The Solution

Use a gear sensor. Thats not so tough, right? First of all, what is a gear sensor? Its a little box, with a little wheel inside. You run your shift cable thru the little box, in one side and out the other (which means you need to cut and re-section your shift cable housing), with the cable running across the little wheel. When the wheel senses any motion, it sends a signal to your motor that cuts the power for a split second and takes the pain away from your drivetrain when a shift occurs.

Whats Wrong With That?

Nothing, so long as it works. The little wheel inside is mechanical and crud-sensitive. Lots of folks have issues with them not working after rain storms or mud baths. You can solve that by wrapping it somehow to keep the grit out.

I wrapped this sensor in silicone tape to make it crudproof

Its also not the ONLY way to do the job. Like I said, I had my first BBSHD without one. I learned to shift without needing a gear sensor. By the time I built my second bike, I had that method down pat. So yeah sure the sensor is nice but I have already learned another way, and I have found – even though I have bought sensors and have had them right in front of me during a new build – I don’t feel a need for them.

But I sure as hell have a need for the job they do. Everyone does. So don’t let anyone tell you the problem is not real. Its probably the #1 way to snap a chain on a mid drive bike.

Gear Sensor Alternatives

So there are a number of different ways to do this job. I’ll list the one I use last

Use the brake cutoff as a clutch

Its simple: Squeeze the brake handle just a little bit to engage the brake cutoff. That cuts power to the motor and gets you the same thing a gear sensor does. The trick is to not engage the brakes to any noticeable degree and lose any of that hard-won momentum. Interestingly, Magura MT5e ebike brake levers have a special little hinge in the middle of the lever. It lets you do this more easily without engaging the actual brakes.

See that little metal pin in the middle of the lever? That hinge makes this lever a shift cutoff. Touch it with a fingertip, the brake cutoff engages, the motor cuts out and the pads aren’t touched.

Thats nice, assuming everything works. If you are a little jumpy, or the bike is bouncing along a trail or something, then that delicate caress on the brake lever might be a little more than you figured and … well, you get it. We live in an imperfect world. But this method still works pretty good.

Use a cutoff button on the handlebars

This is definitely not a common solution, but it does work, and is what I used on BBSHD Bike #1 until I gave up on it and perfected the method I describe next.

See the green button at the center of the pic? Thats the cutoff switch

What is it? Its just a dead-man switch on the bars. Press it and for as long as you hold it, the motor is cut off. Release it and the motor re-engages. Its a brake cutoff that has no brake pads. The other end of the switch has a yellow Higo/Julet that connects directly to the BBSHD’s motor cutoff plug.

In practice, I found it took too much thinking to reach for the button just prior to a shift. It felt forced and I didn’t take to it. Maybe you will and if so its a dirt cheap and simple method to try that doesn’t involve screwing around with your shift cables.

Adapt your pedal cadence

This is the method I settled on, and even after buying and successfully using a gear sensor, I have never felt a need to install another one. This method is just a natural part of my riding style now and is trained into muscle memory… so I do it naturally and automatically on any bike no matter what. Here’s what I do, in order. These steps occur in very rapid succession so making a shift happen occurs in about one to 1 1/2 seconds.

  • Step 1: Stop pedaling.
  • Step 2: Click the shift (just one gear).
  • Step 3: Start pedaling. Muscle power completes the shift before the motor kicks in

Thats it. Do it fast and its just a quick stutter in your cadence. Changing your BBSxx settings so they are friendly to pedaling helps. The linked settings will cut the motor off fast and start it back up soft. Perfect for completing a shift.

When you get good at this, you will be able to click your shift a hair before the motor stops the rotation of the chainring. My more recent builds use SRAM 11 speed drivetrains that need only about 1/4 of a cog revolution to complete a shift. So if I do it right, I click while there is still a ghost of rotation left that makes the shift, so when I start pedaling again I’m already working with a shifted gearset.

But…

Don’t try and get fancy right out of the gate. Just keep it simple and get the shift done. The high speed fancy stuff will come naturally as you gain experience.

Remember, there is nothing wrong with a gear sensor. They do their job. I just learned how to do without one. Having done that, I don’t feel a need to make the effort to install the sensors anymore.

In an ideal world, you do both. Truth be told I screw up every now and then. With the cadence technique and the sensor backing it up, you are pretty much guaranteed to never snap a chain thanks to shifting like a fathead.

Bafang Mid Motor: Multiple Speed Magnets

Some Bafang BBSHD and BBS02 programming tutorials say Speed Meter Signals must be set to 1 or bad things happen. They are right. They are also totally wrong.

This is going to be a quickee post to show off a little spiff you can do on a Bafang mid drive, and point out something wrong I see in some tutorials or forum posts about Bafang BBSHD / BBS02 settings. Specifically:

The Speed Meter Signal

Put simply: It does not have to be set to ‘1’. But I am getting ahead of myself. Lets start from the beginning:

At the root of the matter is the BBSxx Speed Sensor. If you buy one as part of a kit, or on its own, this is what you get for roughly US$20:

Figure 1: L to R: Sensor magnet, sensor base, sensor and underneath, the two screws used in the install

The speed sensor magnet attaches to one of your spokes. You attach the sensor to your chainstay (usually) and position it so the magnet passes close to it as the wheel rotates. The sensor detects the magnet’s passing and calculates your speed, via a rotation count and knowing your wheel diameter via a separate setting.

Figure 2: The speed meter installed on the chainstay.

So if you buy the typical sensor, you get one magnet, one sensor, and you need to set the Speed Meter Signal to ‘1’. Is that setting because you have one speed sensor?

No. Speed Meter Signals counts the number of magnets. Not the number of sensors. Each magnet is a signal. Got one magnet? Set it to 1. Got two? Three (for a 36-hole wheel)? Four? Change the setting accordingly and it works great.

Figure 3: The Speed Sensor settings from my Luna Black Box, with the setting in question circled.

Why do we need more than one?

The one magnet works pretty good as it is, so nobody really gets too deep into this. Plus nobody sells Bafang speed sensor magnets by themselves. So to do this you are talking about roughly $20 per magnet because you have to buy a whole speed sensor assembly.

But… what if you don’t? Cateye sells a sensor magnet all by itself. It is cheap, widely available and can be gotten cheaper in a 2-pak. Here’s one, close up:

I have found these can just be tightened onto a spoke by hand, and they do not need any thread locker to stay tight (adding some Vibra Tite would not be such a bad idea). Reportedly these magnets work over a much greater distance than their Bafang cousins, which is another benefit.

Get To The Point!

Fine here it is. Look for the speed sensor magnet in the picture.

Figure 4: How many lights do you see, Picard?

There are four lights magnets on this wheel. One every 8 spokes. I have the Speed Meter Signals reading set to 4. The improvement is not earthshaking but I do get the following:

  1. My speed reading on my display updates faster and more smoothly. Quadrupling the signal input is a good thing which is not a surprise.
  2. The Cateye magnets are smaller and lighter by a fair bit than the Bafang magnet assembly. This results in the wheel getting thrown less off-balance than when using that big heavy Bafang doodad (even if you place it opposite the valve stem to even out the weight distribution).
  3. Four magnets placed equidistantly around a wheel make for a more balanced wheel spin. Its minor. But when spinning the wheel with the motor when the bike is up on the stand the lesser amount of shaking is noticeable.

Using just two sensors (the 2-pak of Cateye sensors is only $9.95) gives a noticeable improvement as well. Enough that 4 sensors is not noticeably better or worth even the minimal the cost/effort. I can’t help but think that two magnets means two points of potential failure rather than four. This weekend I’m going to go back to two magnets.

So…

You can take this tidbit as useful in a couple of ways: A cheap, lightweight, stronger magnet replacement or a way to get a better speed signal to your display.

Its not a big improvement, but it is a nice little one.

BBSHD Programming For The Pedaling Cyclist

(But Not For The Throttler)

WARNING. Before you start fooling with your BBSHD settings, take a photo of each screen with your cell phone. If you screw up, you have a quick reference back to your original settings.

The subject of what settings to use when programming a BBSHD comes up now and again. Its a question with a fairly complicated answer that does not lend itself to your typical Facebook 2-sentence post.  So here is the long version. I have my own suite of settings that suit my personal riding style.  I am primarily a pedal-pusher: I want to get exercise when I ride, so I seldom use the throttle. But if you try to take that throttle away, you’ll have to pry it from my cold, dead thumb.

So I want pedal assist that does the following:

  1. Doesn’t lug the motor.  All that does is turn electricity into heat.
  2. Conserves power and extends range.  See above.
  3. Keeps me working, but not too hard … unless thats what I want, and then it has to let me do that, too.

Interestingly, with both my Mongoose Envoy Project and Surly Big Fat Dummy Project, I found what worked great for me on other BBSHD-equipped bikes was completely ineffective on a cargo bike.  I frankly haven’t figured out why this is, but I think it may be because my older builds were just that: Older. Something maybe changed in the firmware.  My PAS settings that conserved major amounts of power while pedaling wound up being totally inadequate. I needed to step up some settings, which I will describe below. While my settings then vs. now are quite different, I don’t see any real penalty in range.

Feel free to tinker using both and see for yourself what happens to your own motor.

How do you program a BBSHD?

Strictly speaking, you don’t. As a for-reals programmer who for most of his life made his living writing code, I have to point out this is not programming even if everyone calls it that. The BBSxx line of motors have a quasi-hidden settings interface. With the right software you can gain access to those settings and simply change them, resulting in big differences in behavior.

Myself, I am using the Black Box sold by Luna Cycles (available here).  The Black Box makes it much easier to go on a ride, tweak as you go and get things just right after only one or two rides. Also, I literally have a half-dozen bikes now with one of these motors. The initial expense of the tool is a lot easier to justify if you are sharing it across the Pacific Fleet.

The other way to do this is to spend about US$18 and buy a laptop cable. Then you use your existing Windows laptop to host the app that you will use to make the aforementioned changes. Here is one place to get that Windows app. I started out doing it this way, but as laptop operating systems evolved I found it increasingly difficult to get Windows to accept the cable’s right to exist. I don’t miss fighting with it one bit.

If there is such a thing as a bible on how to program your BBSHD, its Karl Gesslein’s blog post on the subject (read it here).

If you want to know everything about programming your motor, you should read the blog post linked above.  That post is the definitive tutorial on the interwebs, despite its age.  All I am doing here is calling out some of the things I have done that deviate from the norm, work for me and why it seems that is.  So I will not be explaining things as if you have never seen any of the BBSHD settings screens before.  This article assumes you have at least read the above blog post and familiarized yourself with the screens and settings.

I am not showing original factory settings. Your motor may have settings your vendor considers proprietary. So I am showing screens I have altered and then calling out the bits I consider important.

The BBSHD’s settings are presented on three separate screens: Basic, Pedal Assist and Throttle.

The Pedal Assist Screen (2 of 3)

Yes I know. I’m starting out of order. Its easier to understand this way.

Much of what is on this screen… you shouldn’t mess with. I’ll just hit the high points.

Regardless of what you see here on my own screen, I strongly suggest you leave the first three settings alone unless you know exactly what you are doing.

The Pedal Assist screen on 2Fat – my ti-framed 2wd bike whose motor dates back to about 2016. I use these settings on new motors as well.

Start Current

The lower you set this number, the more gentle it is on the controller and your drivetrain. Experimenting with lower numbers will make life easier on your rear freewheel pawls, and chain. Setting this number low is especially helpful if you are running a cargo bike under load and want to be extra careful. Setting this to lower numbers may also be too little startup assist – remember the purpose of the motor is to help you get off from a standing start. This setting only applies to pedal-assist power delivery.

A typical default number here is higher; often around 10. I have found kicking it down just a bit more is much better for your drivetrain if you have a heavy (cargo) bike; especially one that is loaded. Even if its not a cargo bike, how bad can it be to beat on your drivetrain less? Remember you can always mash the throttle if you want <clarkson> power </clarkson>.

Slow Start Mode

This setting determines how gentle the ramp-up is on your power on start. Starting up too fast can kill your motor’s controller so beware. I am using the lowest setting published in the article I linked above. Here again, why create a situation where you could end up blowing your controller or chewing up your chainrings? I stay on the conservative side.

Stop Delay

A common complaint on the BBSxx motors is that you can stop pedaling and the motor keeps going for what feels like a full second. Its a valid concern. 5 is the lowest safe number for the BBSHD so thats where mine is. This setting effectively means your motor stops when you stop pedaling.

BUT it also leaves a hair of rotation which you can use to your advantage when shifting gears: Stop pedaling and in that instant execute your shift. The shadow of remaining power and rotation will be enough to gently complete the shift (SRAM gears will shift in about 1/4 rotation) and you can start pedaling again almost instantly. I call this a ‘stutter step’ in my cadence and I personally prefer it to using a Gear Sensor which automates the process. Tomato-tomahto. Depends on how you learned to use the drive as to which you like better.

Current Decay

This is a big one. Current decay helps decide when your motor cuts power based on your cadence. A huge complaint about cadence sensing is it causes the bike to run away from you and the rider is just spinning the cranks… its called ‘ghost pedaling’. This is part of a complete solution to that problem.

My philosophy is (and plenty of people disagree with this) if I can pedal at a high cadence I don’t need power assist, since I can spin the cranks. By cutting the power back when I start spinning (a.k.a. “clown pedaling”), I not only reduce power consumption and increase range, I also create a scenario where I either keep going on increased amounts of muscle power (which a high cadence demonstrates I can pull off), or I decide to shift to a higher gear, thereby naturally slowing my cadence and telling the motor to give me back some power.

This in turn has the effect of letting me ramp my cadence back up and increase my speed. Done right, this is much closer to a natural cycling experience and either lets me a) haul ass to my destination on the streets or b) get a hard workout. Or both.

Why would anyone disagree on this point? Easy: If you are running a powered bike on singletrack, and you hit a steep hill that is all muddy and root-strewn, you need to spin to keep yourself going up that hill. If the bike gently ramps back power on you, well thats a dirty trick indeed. So… remember what I am describing here is maybe the magic elixir for street riding; but not for an eMTB running hard singletrack.

Stop Decay

This is another setting that helps govern how fast the motor shuts off when you stop pedaling. Zero milliseconds sounds good to me. Stop Delay determines how fast a motor begins its shutdown after you stop pedaling. Stop Decay determines how fast it fully shuts down after the shutdown begins.

Keep Current

This is another companion to Current Decay. When Current Decay decides to cut back power, this percentage determines how much power you keep. So by setting mine to 40%, I am getting a 60% power cut when I spin my legs past the Current Decay threshold. And my Current Decay setting determines how steep the offramp is down to the lower power level.

Here again remember what a bad idea this can be on an eMTB. This is for city riding and commuting, where you want the benefits of boost but you also want the option of getting some exercise and your terrain is reasonably predictable.

The Basic Screen (1 of 3)

The BBSHD is capable of supporting up to 9 assist levels.  Actually its 10 since there is a Level 0, but that level is (nowadays) a special case that you pretty much have to leave at a special setting and can’t adjust.

Each level is defined with two numbers.  A Current % Limit and a Speed % Limit.  They are, in a word, opaque in terms of what they do, and not easy to understand.

Also I have achieved great results in entirely different ways on different bikes. I’m going to show multiple screens.

This is my ‘old school’ screen. It works as a power-sipper on older BBSHD motors. I can not use this on motors I have built bikes with in maybe the last 2 years.

Note the Level 0 setting of ‘4’ with a speed cutoff of 30%. The intent there was I never really want zero power on pedal-assist and Level 0 provided a very mild bump for times when I am pedaling slowly and going slow… like when on an oceanside bike path loaded with tourist pedestrians, and I am just barely exceeding walking speed.

Here’s the ‘modern’ motor, pedal-assist-friendly version. Note the 25a power reduction (and ignore it).

This one is apportioning quite a bit of additional power, level by level. On the newer motors, this is what it takes. The 25a power reduction shown on this screen is specific to this bike and not something you should read anything into. Just know that the Current box is where you limit the amps for regulatory or other reasons (i.e. this is your maniac child’s bike).

Whats with the Assist 0 setting of 1 and 1 above? Its a requirement of newer BBSHD motors. If you set it to anything besides 1 and 1, you wind up disabling pedal assist. This is far from my preferred setting as you can see above. I originally used Assist 0 for sort of a crawl mode when wending my way through tourist-laden sidewalks, where I’m going just a bit faster than a walk and don’t want to run anyone over, but still want a touch of power. Bafang’s release firmware is a moving target so if this changes I’ll amend this note.

  • Current % is when the power cuts out based on road speed.
  • Speed % is when the power cuts out based on motor rpms

Whats this ‘cut out’ stuff?  Well, remember the ‘decay’ and ‘keep’ stuff we described when going over in the previous screen? These settings help determine when that kicks in. Clear as mud? You’re not alone. ‘Counterintuitive’ is the name of the game when messing with your Bafang motor settings.

Screen 3 of 3: Throttle

So… the pedal assist levels are on the Basic page.  Makes perfect sense. Strangely, the throttle settings are on the Throttle screen.

There are only two things that, really, you should be fooling with here.

End Voltage

Generally this stops at ’35’ or 3.5v. What that gives you is, effectively, a throttle that has two speeds: Completely Off and Full Blast. Not really but it will feel like it.

Instead, if you set End Voltage to ’42’ (4.2v) the result will be a smooth, linear throttle where it will be easy to, say, blip out only 200w of throttle-based assist to your motor while you are struggling to get going after a stop. Being able to dribble out just a bit of power is something your cassette pawls – and your wallet – will appreciate after a few thousand applications. No more clanging noises coming from your poor, soon-to-die rear hub.

Start Current

Hey waitaminute… we had Start Current on another screen too! Yes we did. But that one was Start Current for pedal assist. This one is Start Current for when you mash the throttle.

If you set this to, say, 10%, that means the initial beat-down given to your cassette body by the cluster (that gets jerked forward by the equally unhappy chain) is only 10% max the power of the motor. The rest of the power you asked for gets poured on a split second after that. But the initial shock to the system is reduced by this setting, which has obvious benefits. For a heavily loaded bike where you want a smooth startup on throttle, setting this down to 5 (or less!) should be considered.

Wrapping it all up…

So there you have it. This is FAR from a comprehensive tutorial on the subject. Remember also that everything done here is done for a BBSHD that is running a 14S/52v power system, so if you are, lets say, running 48v… its possible you may want to jigger some of the assist levels a bit upwards. But now you can do it with a starting point.

Last Note:

The settings above are my personal settings. Starting from a stop, my assist will not kick in until crossing 5 mph or roughly 8km/h. If I want assist from a standing stop thats what I use the throttle for. Remember: All this pedal assist sturm und drang is wiped away if you just use the throttle and make it go.

Remember… Take pictures before you click Save

The BBSHD: Musical Chainrings

It seems inevitable.  When I build a bike, I go through front chainrings trying to get the gearing just to my liking.  My Mongoose Envoy build has pretty much set the world record for tweaks in this regard.  But gearing wasn’t the problem so much as chain alignment.  Alignment is one of the most talked about issues with mid drives and up to this point I have not had to work too hard to get it right.  This build, not so much but I think I finally got it (like $350 later).

While dealing with this I have fooled around with three different sets of crankarms (160’s, 170’s and 175’s).  Not the subject here so if you notice the different crankarms in the pics, I am ignoring them on purpose.

Sidebar:  When building the Surly Big Fat Dummy, I found exactly the same thing as I did here insofar as chain alignment is concerned.  And used the same solution – the USAMade adapter listed as an Honorable Mention below got pulled out of the parts pile and put to use.

The Right Tool For The Job

The Mongoose build is a first for me in many ways.  One thing in particular:  the BBSHD fits the frame really well.  Its a 68mm bottom bracket with absolutely zero chainstay obstruction for the secondary housing.  So I can butt the motor right up against the bottom bracket.  Further, its a lonnnng way back there so chain alignment and misalignment – an inevitable concern with an HD build – is a lot more forgiving since the angles are gentler thanks to the longer reach.  On this bike, if I want I can even forego the offset non-drive side crankarm and the pedals are still easily centered under me.  So the HD is a great fit here.

About That Job…

The Mongoose is a cargo bike.  So it hauls heavy stuff (usually groceries).  It has a secondary job as an unladen backup commuter, but primarily it needs to be optimized to start from a stop while the entire system – with me – weighs 400-450 lbs (180-204kg).  I have really loaded it that heavily so this is not a theoretical exercise.  So I want a big-ish chainring for when I am pedaling fast and light, and still need to be able to get to the big cogs in the back for when I am loaded up and chugging along like a two-wheeled freight train.

Plan A:  Luna Eclipse (42T)

The Luna Eclipse is one of the best BBSHD chainring setups on the market, with a unique ‘wicked’ tooth profile meant to eliminate the possibility of a chain drop under extreme use.  It also has the most extreme internal offset of any chainring option.  This will do the most to overcome the grief visited upon the BBSHD builder by that drive’s secondary housing sending the chainring way out to right field.

Its also gorgeous.  The gunmetal finish I chose matched beautifully with the dark grey frame.  Unfortunately 42T (which is the standard for full-offset chainrings as any smaller and you can’t clear the secondary housing) was not large enough to keep me from clown-pedaling when riding the bike as a commuter.  There was another problem:  Chain alignment.  Running that smaller 42T ring with the smallest rear cog resulted in, after only a few weeks, a whole lot of wear on the inside.  This is why mid drive builds demand the most out of the builder in terms of thinking things thru.  Time for Plan B.

IMG_20200503_123800
Its not ruined yet, but its lifespan sure has been shortened.  this was only a couple hundred miles of wear.

The Eclipse is a proprietary chainring platform, but fortunately other sizes are available.  the largest of which is what I tried next.

Plan B:  Luna Eclipse (48T)

So Plan B was to swap in a Luna 48T ring onto the Eclipse center section to fix the clown pedaling, and to stay the hell off the 12T small rear cog to deal with the alignment issue (I am using a welded together steel cluster for durability and the 12T is alloy and not a part of the welded cluster, so its better to stay off it for the sake of longevity anyway).  I thought that 48T/14T on this bike was the perfect sweet spot.  A small front ring is best when its on cargo duty, and a large one is best when its a commuter.  48T, when used in conjunction with upshifts, gave me pretty much everything I needed.

Pretty much but not everything.  First of all, remember the deep offset of the Luna ring?  It moves the chain inboard 24.8mm which *usually* eliminates the damage the BBSHD does to chain alignment.  Not on the Mongoose, whose narrow bottom bracket effectively papers over all of the sins committed by the motor (at this time I had not yet fully figured this out).  So, as I found with the 42T ring, it was inset too far, even when I stayed off the smallest cog.

So Plan B helped, but it didn’t solve the problem.  After only a couple weeks (I am now checking carefully and frequently) I saw the beginnings of the same wear on the inside of the chainring.  Like the 42T, I had to retire this thing fast so I could use it on some future project.

IMG_20200503_123820
Not as bad as the 42T, but still bad.  Both this one and the 42T looked perfect on the other side.

Sidebar: A mid drive chain powered by a 1500w motor is a chain saw when it comes to components rubbing against it.  That is just a reality of a mid drive and you have to deal with it as part of your design/build process.  When you get it right, you are golden for thousands of happy miles.  Get it wrong and you are sawing thru chainrings and cogs like nobody’s business.

Plan C: Lekkie Bling Ring (46T)

So now what?  42T was too small.  48T was more or less just right.  And the chainring offset that lets me use the inner cogs at great alignment still needs to be reduced or I can’t use anything but the lower gears.  Lekkie has a Bling Ring available in 46T.  It has the same internal offset their 42T ring has and, since I use them on two other bikes I know they are top quality.  At 18.3 mm its offset is quite a bit less than the Luna.  So I got a 46T.  I also added a 2mm spacer underneath it, further reducing the chainring offset to 16.3mm.  That is a whopping 8.5mm less than before so I hoped I would be good on the smaller outer cogs and still let me use the big inners.

And, pretty much, it was.  Chain alignment didn’t seem to be much of an issue, although it still wore down a bit more on the inside.   I was also able to shift up to the biggest cogs in the rear for very low gearing options.  Those are important on a full cargo load and if I am dealing with hills.

But… I flat out missed that 48T high gear for commuting.  And I was still seeing – very slight but noticeable – wear on  the inside of the chainring teeth from the chain, which was still visibly angling outboard a fair distance.

IMG_20200503_123847
This one was on for a few months and had 8.5mm less offset.  But it still shows signs of premature aging.  This was undesirable but livable.

I decided to try an extreme option I had not previously considered.  But on this bike, where all of the normal chainring offset stuff doesn’t seem necessary, it might actually work.

Plan D: Luna 130 BCD Adapter and Wolf Tooth 48T Ring

BBSHD chainrings are generally all proprietary to the platform.  Not so in the cycling world, where chainrings are universal, needing only to match the proper Bolt Circle Diameter for the chainring bolts.  Match the BCD between crankset and chainring and you are good to go.  There are adapters out there in the world that allow a Bafang motor to use standard 104mm and 130mm BCD chainrings.  The problem is they don’t give you anywhere near as much inward offset.  But given my experience so far, maybe I can live with that.  They should fix my alignment on my ‘commuter’ cogs, but will I still be able to use my ‘cargo’ cogs?

In addition to the LunaCycle 130 BCD adapter, I also chose the Wolf Tooth Drop Stop chainring as those rings are best-in-show for this sort of thing on a mid drive.  Attachment to the adapter was a little different than the usual chainring-to-crank operation in that its backwards.  The chainring bolts onto the inside.  I was able to play some games to good effect:  I reversed the chainring so it is logo-side-inward.  Not as pretty, but doing that lets me take advantage of the countersunk bolt holes on what is normally the outboard side.  The countersinking let me mount a bolt so it is almost flush with the ring, which in turn is butted up almost on top of the secondary motor housing.  With the countersinking it now has plenty of clearance.

Plan D Results

FINALLY.  Everything is working right.  The reduced chainring offset means my 14T cog (still not using the 12T for the reliability issues mentioned above) lines up straight back.  This outboard shift did affect my inner cog alignments but I can still get to all of them but the biggest 32T.  I’m comfortable with the angles on all but the second-largest 30T for long term use, and in a pinch, that 30T will work fine.  I just don’t want to stay on it for a week.  So this 9-speed is now a 7-speed and as DIY mid drives go thats still better than a lot of builds can manage.

And worth mentioning, like a lot of what they do, the CNC-machined Luna adapter is freaking gorgeous, and very precisely manufactured.  So much so it really stands head and shoulders above another adapter I got my hands on and was able to compare it directly to.

Honorable Mention: USAMade 130 BCD Adapter

I was surprised at how well this worked and how nicely it was made.  The part only cost me $29.99 on Amazon.  Still, it was Made in USA, well machined and rock solid.  The only things I didn’t like about it was the fact it was machined a bit too heavily, which meant it placed the chainring a millimeter or two further outboard than was necessary, and in this game millimeters count.  Further, as you can see above I was able to reverse the WolfTooth ring and take advantage of the bolt head countersinks.  That didn’t work with this part as USAMade countersunk the outside edge of their part, which made the bolts too long to allow my trying the same trick on the inside, where I needed it.  For a different build it might work fine so I am keeping it for my parts pile.

As for the Stone chainring seen on the USAMade adapter (scroll up to the title image at the top of the page), thats a Chinese Special that ran less than the godawfully expensive Wolf Tooth.  Its noticeably lighter in construction than the WT and I’m not sure I am sold on the tooth profile.  This ring will sit in my parts pile waiting in the wings as an emergency replacement.

Heat Sinks For the BBSHD Ebike Mid-Drive

Not so long ago, someone asked whether heat sinks had ever been applied to the BBSHD with any success.  This reminded me to document what I have done for posterity’s sake.  I turned a motor whose casing temp was 165 degrees fahrenheit and reduced it to 135.  Still pretty warm but a 30-degree reduction nonetheless.

Whats The Problem?

Well, there isn’t one, actually, unless you are really beating on the drive.  Even then its only going to be an issue under specific circumstances.  The fact is, these motors are pretty well built and they generally don’t suffer from heat issues.  Unless…

  • You are running the motor on the street, say, on long city blocks, and either laying into a high level of continuous pedal assist, or the throttle

AND

  • You are running the motor on a 52v battery, in its max 30 amp configuration

AND

  • It is REALLY hot outside.  We are talking 100-110 degrees fahrenheit (38-43 Celsius).

So, we’re talking summer commutes or midday shopping runs in Central California on streets like this, where my bike – which I geared for proper pedaling at 28+ mph – is putting out 100% power from the motor, continuously in between stoplights… and its a long way to the next light.

ScreenShot033
I’m riding in the Class 3 lane on the street, not the Class 1/2 shared use path just to the right

Put all of these things together and now you have a motor that gets hot.  How hot?  My Stormtrooper – A rescued Motobecane Lurch frame with carbon fiber 90mm deep dish wheels, 52v 30a BBSHD, and a Luna Lander front air fork – was seeing motor casing temps of 165 degrees.  Yikes.

IMG_20190827_082401
The Stormtrooper – Now living the good life in Pacific Grove, CA where it is never hot, unless its on the inside of a freshly baked cheddar bagel.

So…. what can you do?  On this bike, I added a whole slew of 8.8mm x 8.8mm x 5mm heat sinks – purchased with thermal adhesive already applied so they are just peel-and-stick.  Here is a link to the source I used.  You can find them quite a bit cheaper buying direct from China but you will wait a couple of months for them to arrive.  When done, the motor casing looked like this (I completely encircled the motor so there are many more of these things on than you can see here):

IMG_20180609_091021
The small heat sinks are placed in rows, 4-across.

Next, I put on another large round heat sink on the end cap.  Since it was sold to me in bare alloy, I used radiator paint (for minimal impact on heat transfer).  I also had to apply my own heat transfer adhesive.  I chose this style as it had the large center area that could be used for adhesive.  Note I also had to fill the very center of the motor where there is a gap thanks to the laser etching for the logo.  I did this with 3+ layers of thermal adhesive, cut to fit flush.

IMG_20180609_090732
You can see the thermal adhesive I applied to the center alloy section of the end cap, just at the top.  Hand cutting the adhesive strips to fit was a pain.

Here is a different motor where I used different heat sinks.  These are 8mm x 30mm x 8mm in size.  So they fit – again almost perfectly – in the smooth channel on the BBSHD motor casing.  This time you only need to stack them as they fit the channel 1-across.  Much easier.  Also they are a bit taller, with more room between the fins.  Is that better or worse then the little 5mm units?  I haven’t done any testing so I don’t know.  On this motor, I did the same end cap as pictured above.

IMG_20180630_081347
These 30mm-wide sinks were a lot easier to apply as you only have to go 1-wide all around the motor.

Here is a link to the 30mm heat sinks I used.  I can’t find a domestic source for these so if you decide to go this route you just have to order them from the source … and wait.

On the Surly Big Fat Dummy I recently built, I used them again.  They make a major difference in the intense heat we get here in the California Central Valley

By the way, these identical heat sinks work extremely well on a mini-Cyclone… Those motors overheat if you give them a dirty look.  The same combination of 30mm adhesive sinks mounted radially, plus the same end cap.  Takes the surface temperature down to the point where the motor can be used with relative confidence once you learn not to overdo the throttle and cook it… The heat sinks cool the motor from the outside literally as much as is possible under the circumstances.

Mongoose – Chapter 8 (Low Cost Builds)

So in Chapter 8, I put up a Build Sheet.  If you do all the math, you will find my $750 bike turned into a $3600 bike (some bits, like the battery, I already owned and just plugged in so cashwise I am not out the full parts total).  Given how expensive quality cargo bikes are, and the level of quality I have now, I am very happy with that cost vs. benefit.  I have a really solid frame and top quality components, and a bike that is probably the best all-around transportation/auto replacement bike I have ever owned.

But what of all of this was actually necessary?  I build bikes as projects.  Generally, I am more concerned with making the bike the best it can be.  I don’t pay as much attention to final cost as most people would.  Especially since I oftentimes upgrade in bits and pieces, which is less of a shock to the budget.

Based on my experience with the stock Mongoose bike – seeing first hand what worked, what didn’t and what I changed because I had more money than brains – I can see a different way to go that might be of a lot more interest to people who just want a good bike that doesn’t break the bank.  For the record, I’m of the opinion that the Mongoose Envoy represents a significant break from current cargo bike offerings in that it can be built into a first class solution for a lot less, thanks to its bargain basement starting price.

So… lets build a few different configurations using my kitchen-sink, spaghetti-against-the-wall build.  In the end, I replaced everything but the frame, headset and fork.

All prices are in US Dollars.  The last two builds are non-electrified.

Build #1:  Just The Very Basics+Assist ($1,807.48)

This is a low-cost build that changes only the things that I think must be replaced.

Right off the bat, you can see I left on the Magura 4-piston MT5 brakes, and the great big (but relatively inexpensive) thick rotors.  These brakes work so smoothly and so well when I have had this bike fully loaded.  I think you’d be insane not to take any and all uncertainty completely out of your braking equation.  These brakes are not overly powerful when you consider the duty cycle they will have to put up with.  Safety first, but this choice also guarantees trouble-free ease of use.

This build uses the BBS02 because it is lower-cost and still does a spot-on job.  You can see from my motor choice post that if I did not already have other BBSHD bikes in my stable, I would have chosen the ’02 for this build as it is ideally suited for the cargo bike job.  The cost below does upgrade to the mini color display; adding $40.  Knowing the different displays as I do, this is well worth that minor upcharge.

Note I changed the shifter… that has to happen thanks to the change in brakes.  The stock brake levers are combined with shifters (cheaper that way, I bet) and if one goes, so must the other.

Mongoose Envoy Bike               Amazon               731.49
Magura MT5 disk brake set         bike-discount.de     137.00
ISH-203 203mm rear disk adapter   bike-discount.de       6.86
QM5 203mm front disk adapter      bike-discount.de       6.86
Tektro 203-17 downhill rotors (2) ebay (hi-powercyles)  42.40
MicroSHIFT TS70-9 shifter         Amazon                22.88
BBSO2 motor kit                   Luna Cycle           490.00
   68-73mm standard motor
   mounting hardware
   wiring harness
   speed sensor
   basic crankarms
   Luna 500C mini color display
   Universal thumb throttle
Battery Solution
   52v 12.5ah battery pack, basic Bicycle Motorworks   369.99
   pack construction, 50a BMS and
   Samsung 25R cells

Build #2: Change Out The Drivetrain ($1,933.00)

Includes everything above, plus the following, which adds $144.61 to the build price.

Everything From Build #1 plus...
KMC X9.93 chain (7 feet/more links)  Luna Cycle   57.75
Shimano HG400-9 12-36T cluster       Amazon       25.99
Shimano RD-M591 9spd derailleur      Amazon       41.78

This takes out the frankly bottom-end Shimano drivetrain and in its place substitutes a smooth-as-glass 9-speed click-shift setup.  Yes the chain is expensive but if you want to do a mid drive right, you have to pay attention to the chain and the rear cluster, which in this case is a durable, steel, welded-together unit that will give longevity and will not tear into your cassette body.

You can get a strong steel cluster with an 11T small rear cog, and I suggest you resist the temptation.  11T cogs are always problematic on mid drives in the first place.  On a cargo bike the problem is worse.  The speed you can achieve dropping that one tooth is likely unattainable anyway.  Especially when you factor in the weight and the motor-bogging that will occur under load.  Don’t do it.  Get the 12T.

Worth noting:  The stock Mongoose 8-speed cluster is also a welded steel unit so its just as survivable.  Also the Mongoose chain is an 8-speed KMC, so its likely just as durable.  The weak links – no pun intended – are the rear derailleur and shifters.  Mine worked poorly although I intended to replace it with a 9-speed from the get-go, so I didn’t try to adjust it into compliance.

At this point, we have a really first class electrified cargo bike that stops easily, shifts smoothly, will survive over the long term thanks to the components we plugged into the drivetrain… and we’re still under 2 grand.

Build #3: Add a Front Rack ($1,988.48)

Yikes we’re still under 2 grand here!

Everything From Build #2 plus...
Front Rack 
   Axiom Streamliner Front Rack  Amazon       46.99 
   Delta AxelRodz skewers        Amazon        8.49

Adding the front rack greatly increases your versatility.  For mine, I use waterproof RockBros 27L panniers similar to Ortlieb rolltops: They are big, carry a lot and mount about 2″ low on the rack.

Note my discussion of the installation of this rack in the Odds and Ends post.  You’ll need to spring for about 20 stainless 5/32″ fender washers to fit the rear AxelRodz skewer onto your front axle.  This sounds crazy but really, it works very well.

Build #4: Beef Up The Drivetrain ($2,187.43)

We’re adding almost $200 with just these next two parts.

At this point, since we are building with a BBS02, we’ll want to address its weak links a little differently than I did with my BBSHD.

The Lekkie chainring gives you some offset to bring your chain line back into alignment, provides a tooth profile that eliminates any chain drops and lasts, essentially, forever provided you do your part as described in the mid-drive section of the motor musings chapter.

Everything From Build #3 plus...
   Lekkie Buzz Bars (crankarms)  California-ebike    99.00
   Lekkie BBS02 46T chainring    California-ebike    99.95

As for the crankarms, those are self-extracting, quality bits of forged alloy, versus the low-end Chinesium alloy used on the stock arms.  Those square-taper arms are often replaced, and the fact they only cost about $15 each makes said replacement relatively painless… but never having to replace them in the first place is an idea that has some merit.

You can consider the crankarms an optional option and see if you pedal hard eough to make them fail, which you might not, in which case you’ll save yourself a hundred bucks.

Build #5: No E-Assist, Proper Parts ($1,081.69)

What about just treating the Envoy as a ‘donor’ to make an analog bike?  Take advantage of the great frame and replace the iffy components to make yourself something really good for really cheap?

I did not throw on the hand built uber-wheels, or change the tires.  Both of those components work well on the stock bike.  Sure I think custom wheels and upgraded tires are a good idea, but they are icing on a cake and, particularly with the wheels, spike the build price up considerably.

I focused on turning the bike into a silky-smooth-running, safely-stopping hauler.

  • The drivetrain – excepting the front crankset – was replaced with a great Shimano 9-speed long cage derailleur
  • The chain may seem expensive, but you’ll have to buy two 9-speed chains to make one long enough to fit this bike, or just buy the super-strong one I did that is in one piece already with no potential mid-chain weak spots where the two chains would otherwise be attached together.
Mongoose Envoy Bike                Amazon            731.49
Magura MT5 disk brake set          bike-discount.de  137.00
ISH-203 203mm rear disk adapter    bike-discount.de    6.86
QM5 203mm front disk adapter       bike-discount.de    6.86
Tektro 203-17 downhill rotors (2)  ebay               42.40
MicroSHIFT TS70-9 shifter          Amazon             22.88
Shimano HG400-9 12-36T cluster     Amazon             25.99 
Shimano RD-M591 9spd derailleur    Amazon             41.78
Shimano FD-M591 derailleur (front) Amazon             29.95
KMC X9.93 (two of them)            Amazon             36.48

Build #6: No Electrics, Fully Loaded ($1,566.41)

This one has almost everything but the kitchen sink thrown in for max comfort and quality.  Here again though, I left off the hand built wheels.

  • The Thudbuster LT is pricey but its such a big change to the comfort of the bike, a top build has to have it.
  • $90 for a kickstand is hard to choke down, but if the bike falls over once at the store with 100 lbs of groceries in the bags… it doesn’t seem quite so expensive.
  • Those Jones bars are just too comfortable.  Nothing wrong with the stock bars… but if we are throwing on stuff to feel good, these have to be on the list.
  • I use the RockBros panniers with my own front Axiom rack and decided to include them here.  They are big, waterproof and inexpensive.  While you do not want to overload your front rack, these can carry jumbo bags o’ tortilla chips without squishing any.  So as usual, size does matter.
Everything from Build #5 plus...
Thudbuster LT 27.2 XL            Amazon      119.99
Ursus Jumbo Superduty kickstand  Amazon       79.99 
Jones H-Bar SG Loop Handlebars   Jones Bikes  79.00 
Jones 205mm Kraton Soft Grips    Jones Bikes  20.00
Front Rack 
   Axiom Streamliner Front Rack  Amazon       46.99   
   Delta AxelRodz skewers        Amazon        8.49
   RockBros 27L Panniers         Amazon      108.99

Wrapping it all up…

The first four builds above address all of the functional weaknesses of the $730 Mongoose Envoy.  Do these things and you have

  • upgraded an analog bike into a solid electric performer
  • addressed every functional weakness in the original bike

The last two builds take a look at the same thing, but go in the direction of making the bike the best it can be without a motor.

One functional item I am leaving off here is a heavy duty wheel build.  While I have one in progress, and its on the build sheet, the fact is I have not yet killed the stock wheels.  Nor have I ding’d them.  They are still nicely true, and my desire for a 30mm internal, survive-the-apocalypse set of wheels can be argued as me overdoing it… again.

There are a lot of other line items on my personal build sheet that are not discussed on the electric builds.  Stuff like the Thudbuster seatpost, or the Jones bars.  These address personal comfort issues that don’t need to be there.  Those are items you can spring for individually over time… or not.  You know how the bike upgrade thing goes…

So have at it!

Mongoose – Chapter 6 (Odds & Ends)

This section holds various bits that I changed that do not fit anywhere else or do not merit their own Chapter.


The 76L (each) Panniers

This needed its own writeup and, since it happened after the bike and these chapters were finished, got its own pair of standalone posts.  In the months since I first put them together, they have proven perfectly durable and saved me about $200 over commercial bags of about the same size.  Big And Cheap: DIY Cargo Bike Bags.

Front Rack

This bike cries out for a front rack.  It is after all a cargo bike, and loading it up is part of the game.  Sure, weight on the front wheels is not conducive to stability, but if you have ever done a bicycle tour, you’ve learned to deal with the issue.  Besides… for a grocery getter, a front rack with a couple of nice big panniers is perfect for bags o’ potato chips, loaves of bread or similar high-volume, low weight delicate items.  I do have to admit… one time I loaded the front bags up with soup cans.  That made for a hair-raising ride home.

Normally on my fat bikes, I use an Axiom Fatliner rack, which is rated for a whopping 50 kg (110 lbs).  For this nonfat bike, the Axiom DLX Streamliner is the next best fit, and it too is rated for 50 kg.  Now… you’d be out of your mind to load that much onto it, but its nice to know it can handle a lot more than I will ever put on.

Axiom racks use an oddball kind of armature that threads thru the QR skewer and shifts the rack rearward a bit.  In this case, I am going to take a rear rack and stick it on the front… so those mounting arms will shift the rack further forward.

Here’s where it gets weird:  A common complaint on this rack is the arms add *just* enough width to make it difficult or impossible for your skewers to fit over the arms.  I had exactly the same problem.  No way was it going to fit.  I tried using Axelrodz skewers whose front skewer was – on paper at least – long enough to work.  It wasn’t.  So I came up with an alternative that ended up, if anything, working better than if things had fit right (and still used an Axelrodz skewer).  Look at the front axle closely in the pics above.  It doesn’t look quite right…

I keep a supply of stainless steel 5/32″ fender washers on hand as they are cheap, easy to buy by the box at Ace Hardware in any US town, and a perfect fit for an M5 bolt.  More snug than an actual M5 large-area/fender washer, in fact.  Since they are large-area, they are just a smidge wider than the skewer’s contact area with the fork.  They are also just as wide as the contact area of the rack mounting arm.  If I stack a half dozen of them on the axle, the rack – which was meant for a 135mm rear mounting – fits much better, with perfect full-contact with the washers.  If I stack another half dozen or so on the outside of the rack arm, then clamp down a REAR 135mm axle rod… Job done.  If I remember right, I used 6 washers on the inside, and 6 more on the outside.  I set it up so there is absolutely full thread engagement on the rod.

Doing this also eliminates the risk of someone walking up, flipping the QR skewer off and wandering off with my front wheel.  An M5 hex key lets me pop off the wheel easy-peasy, almost as quick as a quick release.

Parts List:

  • Axiom Streamliner DLX rack
  • Axelrodz QR skewer replacements
  • 5/32″ stainless steel fender washers

Thudbuster LT

I have maybe 3 of the Thudbuster Short Travel posts on other bikes, and one Satori Animaris – a $50 alternative that I found well worth the money with virtually no downside vs. a Thud ST.  But for the Mongoose, I decided to go to a Thudbuster Long Travel post.  I bought the XL version which is a full 450mm long.  Not so much because I need it (on this large frame, a normal 400mm would have worked fine) but so I can potentially use it on a smaller frame if I ever need to swap it out.  At about $150 a pop these suspension posts are pricey.

Having many thousands of miles under my … belt … riding short travel suspension posts, this is my first long travel version.  I wish I had bought long travel all along (and in fact since I got this one, I retired my Satori Animaris for another Thud LT on my daily driver bike).  The trick to getting this to work right is to adjust the pre-travel screw so its already pretty stiff when you give it a shove with your hand or upper body while standing next to it.  When putting your full weight on it, it will move quite a bit but you won’t realize it.  But your bum will.

I installed a thudglove neoprene cover.  Not so much to keep it clean – its a city bike after all – but to make my use of a $150 seatpost a little less obvious.  I took a black sharpie to the white lettering on the glove to tone down the advertising volume a bit.

I also used a seat leash.  These are not ironclad theft protection, but they will stop anyone from a quick grab, and if you have a bolt-on seatpost clamp like I do, even loosening that will not let someone walk away with the seat.  They will have to disassemble the seat from the post itself to be able to walk away with the seat, or the post, or both.  Of course, if the thief has a decent set of bolt cutters, or an angle grinder, they’ll make short work of this, but the leash is a great security measure against all but the prepared, dedicated thief.

Parts List:

  • Thudbuster Long Travel XL (450mm total length) in size 27.2
  • Thudglove
  • Seat leash cable for a bit more theft protection

Dual Seatpost Clamp

A seatpost clamp?  Really?  Picking nits, are we?  I’ll explain.  This is kind of a big deal, actually.

The Envoy comes with a typical quick-release seatpost clamp.  It works, but you figure out real fast you have to absolutely clamp the bejesus out of it to get the post to stay still… Unfortunately it turns out the seat tube of the frame is just a hair over sized.  So the seatpost is going to require unusual amounts of force to fix it in place.  This is not so great for the frame.

Its even worse when you want to substitute in a quality seatpost; in my case a Thudbuster to soften the ride.  The Thud’s ribbed-but-polished-anodized surface is just slick enough that the QR post clamp simply will not work unless I clamp so hard I fear for the frame’s survival.  This is after all an alloy frame, and alloy often prefers to break before it bends.

I did manage to get myself a thicker wider-clamping-area carbon fiber clamp on Amazon for about $12.  When clamping that to frightening levels (and only then) I found it could hold the Thudbuster steady… although I did not test it for more than a couple of rides.  I replaced it with this doodad as soon as it arrived:

seatpostClamp
You want the exact sizes shown in the image above.  27.2mm for the seatpost and 31.8mm for the seat tube of the frame.

I bought it on EBay for about $25 (You can also find them on AliExpress.  Amazon sells the ‘KCNC twin seatpost clamp‘ for about $40).  It turns out dual clamps exist because carbon fiber seatposts tend to slip.  Why does this design fix the problem?  Clamping both post and tube solidifies the connection.  Considerably.  I have had no shift whatsoever in my post height since installing this piece, and I didn’t have to put undue stress on my not-replaceable frame.

You may have to do a little extra searching to find this specific type of “double seatpost clamp” versus one that simply is thicker and has two bolts.  Those frame-only clamps put all the extra stress on the frame which is not my preference.


Ursus Jumbo Kickstand

The stock kickstand is a good product, but when you have loaded up the Envoy after a Costco run, you’re on shaky ground even if you are absolutely level: Bump the bike wrong or let the handlebars with their laden panniers flop around, and the bike can easily tip over.  It does after all, weigh probably another 140 pounds or so and thats before you climb on.

I asked around at the Cargo Bike Republic group on Facebook and one of the options was the Ursus Jumbo kickstand.  Its an $80 option, but believe it or not its not the most expensive option by a long shot.

IMG_20191019_154232
You can see the extra wide Ursus stand above.  In this picture, the bike is loaded with well over 100 lbs of Costco booty.  Note I loaded the bike way too close to the rack. I was unable to roll it forward to raise the stand.  Next time:  turn the bike completely around before loading.

The stock stand spreads about 7 inches, or just under 18 cm.  The Jumbo on the other hand spreads over 40 cm.  It also keeps the front wheel only *barely* off the ground.  Perhaps a half inch.  Thats a good thing as I see it.  Raising the kickstand while the bike is loaded is a different approach to the stock stand, where you push the bike forward and gravity + momentum force the stand to retract (with a thunk, and the bike plops down at the same time).  With the Jumbo, you physically pick the bike up at the front and retract the stand while its in the air.  Different, and more difficult for sure.  But the added stability is dramatic.  Its worth the extra effort.


Jones Handlebars

With clear/soft Kraton grips. 

I’ve taken to Jones H-Bar handlebars on all my bikes after an inattentive driver hit me back in December of 2016.  The resulting injuries left me with wrist pain that I can only deal with for short rides.  The Envoy has a similar handlebar design, 710mm wide with a less-pronounced 27-degree sweep vs. the Jones 710mm and 45 degrees.  Unfortunately I’ve decided the sharper angle of the stock handlebars is too much for me.  They are a good effort from Mongoose to provide a well-functional bar out of the gate… but if I want to go on 15+ mile commutes the discomfort is unfortunately spoiling the ride and lasting well into the next day… when its time to go ride again.  The Jones bars are a known fix to this problem for me.  Highly recommended on general principles.

Parts List:

  • Jones SG flat bars
  • Jones clear/soft Kraton grips

Custom Built Wheels

Given the kinds of weights I am dealing with in a cargo application, I wanted an indestructible wheelset.  Worth noting:  The stock Mongoose wheels never let me down and never took so much as a shimmy; always staying true.  Further, the steel cassette body showed zero wear after 300 miles of use with the BBSHD motor in play.

I knew right off the bat I wanted to build the wheels with a DT Swiss 350 Hybrid rear hub.  The Hybrid is an insanely sturdy hub designed with ebikes in mind.  Compare it to the already mighty 350 Classic and its … well, you’ll never break it.  the 350 Classic’s super strong splined engagement system has been upgraded from the already-best-in-class 18T to a 24T for even faster engagement, and the spline wheels are solid rather than the stock units which are now skeletonized.

A DT FR560 is my rim of choice for indestructibility on an enduro bike, and they would have been my choice here, but I’m trying to keep the cost down… and I found the Sun Ringle MTX39, which is tailor made for downhill and freeride nightmare rides, making it also perfect for cargo.  It makes for a crazy strong wheel like the FR560, at half the cost (and maybe twice the weight 🙂 ). 

SIDEBAR:  I went 32H not realizing the 350 Hybrid uniquely comes in the unusual-but-preferable 36H configuration.  Since the MTX39 is also available in 36H, and so are Shimano front hubs… I could have done an even stronger wheel build.  Frankly given the components in use here (DT Alpine spokes are just as overbuilt as everything else on the parts list) its almost hard to imagine needing that extra bit of strength, but I would have done it if I had realized the rear hub had that option before I ordered my other parts.

  • Sun Ringle MTX39 Rim 26″ 32H (30mm internal width)
  • DT Swiss 350 Hybrid ebike/tandem rear hub.  Steel cassette body, 24-tooth splined ratchet engagement.  148mm thru axle converted to 141mm QR.
  • Shimano M475 32H front 6-bolt disc hub
  • DT Swiss Alpine spokes

Stock Mongoose Envoy rims are on the spec sheet as 26mm internal width, when in actuality that is their external width.  Internal width is 20mm which is ok but nothing to write home about.

Likewise I could spend much more on a front hub, but a workhorse basic Shimano hub will do the job just fine.


12ah Portable Battery

Full description pending.
My battery needs to be easily removable as I carry it into the store with me.  It also needs to be easily concealed in the store as I don’t need someone seeing thick red wires and thinking I have a bomb in the bottom of my shopping cart.  Also, my runs to the store are usually only a few miles from home, so I can get away with a smaller battery, which – double bonus – is easier to lug around.


Tires

I’ll admit it.  I’m a tire whore.  I’m always looking for something a little better, a little different, and oftentimes I don’t wait for one set to wear out before I jump ship and throw on a different set to see if I have finally found the Grail.  Usually, I have a stack of the things sitting in the garage, as a result.  Since the Mongoose has 26″ wheels like my old Stumpjumper FSR, which I converted to a street bike powered by a Cyclone mid drive, I already had some tires in the pile to play with.

Naturally, I didn’t use them right off and instead bought more.

Firstly, the stock Chaoyang tires are decent.  They are rated 26×2.35 but in a first for Chaoyang, exceed their size spec and measure out to have a casing 2.5″ wide at a comfy 50 psi.  Pulling them off the rims, I found their casing to be thin-ish but not unnervingly so.  A basic tire I would expect to work well with no special flat protection.

Continental Contact Plus City 26×2.20

I replaced the Chaoyangs with the largest flatproof tires I could get my hands on.  The Contis are bigger than the Other Leading Brand best-in-class tire, the Schwalbe Marathon Plus.  I know from past experience that Continental seems to be trying to beat Schwalbe by putting out comparable tires and selling them at much lower prices. I use the Contact Plus tires in 700Cx37 and they are absolutely as good as the Schwalbe competitor, but are half the price.  That tread is not available in a large 26″ size, but the ‘City’ version is.  And since the Marathon Plus only goes up to 26×2.0, this appears to be the biggest flatproof tire out there.

Like the other Conti tires I use, the tire casing is actually smaller than rated, and stretches over time to approach but not quite reach the rated width.  At installation these tires were 2.15″ wide.  After a week or so, they had stretched to 2.2″.

81sob6j+stL._AC_SL1500_
Why is there a caption here?  You can read the label in the image.

A smaller casing is not really what you want on a cargo bike, but I expected these tires to be really solid; making up for the loss of volume.  So far that expectation has been met.  These tires qualify as tank treads, and they roll smooth as silk.  There is enough tread articulation to make me comfortable using them in the wet, and not so much that there is any vibration of any kind while rolling.

Under load, with my 250-lb self, 140 lbs of cargo, 55 lbs of ebike and a 60 psi max inflation, the tires performed just fine without any worrisome flattening of the tire profile under load.

Some other tires I have in the parts pile:

CST Cyclops 26×2.40

20-x-1-95-cst-c1381-cyclops-tyreStupid cheap but well made tire that is essentially a Maxxis Hookworm – reportedly made on the same tooling as the Gen1 version of that wonderful tire.   The Cyclops has thinner sidewalls but really, they are decently thick.  The Hookworms are thicker still.  This is a really nice, smooth roller with grippy tread articulation for a sure grip.  If you want a $25 tire you can count on (I got mine on sale for $15 each), this is it.

Schwalbe Crazy Bob 26×2.35

513CxGYqhdL._AC_I use these on another bike and in this size, these tires are E50 rated for moped use (says ‘moped’ right on the tire casing).  They are really thick, solid tires although they lack puncture resistant belts.  The bead-to-bead tread means you can heel a bike over hard with these shoes on.  Not something you need with a cargo bike, but these tires are a solid choice.


Tubes

I’m not doing the tubeless thing here.  Instead, I’m going for the monster bulletproof setup.  The outside layer being the super thick Conti tire, with the inner layer being a slightly oversized thornproof tube.

4115tFiMDhL._AC_

An oversized tube is good since it does not distend/stretch as much when inflated.  Long term they are less flat-prone.  This particular brand of thick tube has issues with the tube separating from the valve stem if it is stretched.  I am experimenting with applying Shoe Goo to reinforce this area.  We’ll see.

A big part of the draw of these tubes is not only are they thorn resistant, but they also have removable valve cores, which facilitates the addition of slime into the tube.

So…

  • flatproof tire
  • Thorn resistant tube
  • Slime in the tube.

Hoping for no flats, ever.


The Ridiculous Lock

Nothing, and I mean nothing, is safe from a portable angle grinder.  But this is as close as you can get.  This setup rides in the brown bag you see in many of the pics about this bike.  This 14 lb ensemble and its keys are permanently along for the ride.  Details to come.

  • Pragmasis DIB motorcycle grade U lock
  • Pragmasis 13mm boron steel chain, 2 meter length
  • Lockitt motorcycle roundlock

IMG_20191019_145024.jpg
This is how the bike looks when its left outside.  Roundlock nooses the frame and rear wheel.  U lock grabs the front wheel.  four separate 2-minute cuts with an angle grinder are needed to get this bike rolling.  Note if I was being smart I would have done something to get that chain off the ground.

.

IMG_20191011_135210.jpg
All the bits laid out.  The cloth cover for the chain has been slit at just the right spot and sealed with heat.  The bag has since been lined with some custom cut foam padding so this abomination doesn’t rattle while riding.

Mongoose – Chapter 2 (Brakes)

“My brakes are too effective” 
— said Nobody, ever

I am a firm believer in Big Brakes.  I learned when building a hot rod track car that everybody pours money into motor and suspension, but brake upgrades often come as an afterthought (usually accompanied by soiled underpants).

As a daily bike commuter, I also want trouble-free operation.  And since what I usually ride is a big, fast, heavy ebike, I appreciate big brakes a whole lot more since I am riding a rolling worst-case scenario.

Now, the Mongoose Envoy donor bike is the subject of this series, and it is not a fast bike.  It hauls lots of stuff though and thats probably worse than merely shucking speed.  So far, I have loaded it with about 140 lbs of groceries in addition to my own 250 lb self.  Add to that the bike’s roughly 50 lb weight.  With all that, the brakes that come with this bike from the factory really have their work cut out for them.

I suppose those factory brakes are OK… If I set aside how spoiled I am with my usual upgrades.  I can see they are about average for a low-cost bicycle.  While I wanted to keep this bike’s cost down, a couple things pushed me to upgrade.

First, out of the box the front brake essentially did not work at all.  It seems it was so poorly adjusted that all it did was caress the front rotor and do nothing to help stop the bike.  This was after I adjusted the inner and outer pad positions (the stock brakes have a dial for each side) as well as the caliper on its mount.

The rear brake … well, it did apply what I would consider to be moderate pressure.  A bit light but in the ballpark of what you’d expect from a cabled system.  But there is a long cable run to the back of that long frame.  A fair bit of my brake lever travel was eaten up by flex in the brake line, between lever and caliper.  An inspection of the brake housings showed they were not lined/compressionless – not a shock given the bike’s price point, but bad news for braking.

My initial solution was a game I have played before, and I should have known better… but I wanted this bike to be low-cost, so I tried a half measure:  I upgraded the calipers to Avid BB7’s (I had a spare set in my garage), which have a very good reputation.  But no matter what they are still cabled brakes.  I ended up wasting half a day trying to get them just right and never did.

The front brake came together quickly.  It didn’t want to stay in adjustment but thats what you get with cables.  Its stopping power was just fine.  It was the rear brake that was a waste of time.  I tried every trick in the book to get it to be effective – perfect was never an available option.  Most of the blame goes to the aforementioned flexy cable housings.

And mounting them?  Avid calipers use a semi-hemispherical washer set above and below the caliper to allow it to be angled if need be, and that makes its positioning options quite fluid.  The height was never correct and there was always some kind of rubbing somewhere.  Regardless of how I shimmed or re-jiggered it, something was not right somewhere.  I like to think of myself as something of a brake whisperer – if a brake set can be finessed, I can get the wheel spinning perfectly without so much as a touch from a misaligned pad or rotor.  Not this time.

So I said to hell with it and went back to my old standby.  Magura MT5 hydraulic brakes.  This makes my 5th set across my 2-wheeled fleet so I am pretty familiar with them.  Why these brakes?

  1. They are powerful.  4-pistons in the caliper means four clamping points onto the rotor.  Its like the difference between grabbing something with one hand versus using both.
  2. They are smooth to activate.  Unlike cabled brakes, you can use one or two fingers to gently tug on hydraulic brake levers.  For the Maguras, they have lots of travel so it is easy to modulate the force applied.  Despite their power they are very gentle unless asked to be otherwise.
  3. They are dirt-simple to install.  Use a Magura adapter to match your rotor size and bolt the caliper directly to it.  Done.  The use of Magura adapters coupled to their caliper results in a perfect height every time.  No shimming.  No dinking around with axes and semi-hemispherical washers… just bolt it on, eyeball it to center and tighten down.
  4. They self-adjust.  Yup thats right.  You centered the caliper at installation.  The pads align themselves.  Really.  You won’t mess with them again until you wear the pads out.

Ordinarily you pair these brakes with a Magura Storm HC rotor.  These rotors are 2.0mm thick, which is thicker than the typical 1.80mm thickness most rotors(including the stockers on the Mongoose) come in at.  In addition to having more meat on them to do their job (a rotor is a heat sink and more metal = more heat sink) thicker rotors are less inclined to warp.  In fact I’ve never seen one do that across any of my bikes and thousands of miles.

20170415_112904.jpg
This is a fresh Magura Storm HC 203mm rotor just after installation on an ebike.  Notice the heat discoloration from the brake bedding that was just performed.  Also note the caliper is bolted straight onto a Magura brand adapter with no need for shims.  Matching the brand on caliper, adapter and rotor makes for perfect alignment.

With all of that said, I have found a better rotor than the Storm HC – the Tektro Type 17.  Its designed for downhill bikes, who need to stop under the most extreme of circumstances.  These rotors are 2.3mm thick and as such are even more substantial – and even less likely to warp.  They fit perfectly on a Magura braking system, with the tops of the rotor ‘waves’ matching the top of the pads, and only a hair of lower rotor surface being untouched… not because the calipers are misaligned… there’s just more rotor face than you can use.

Here is one of these monsters, installed.  Note the marks left by the pads on the surface, and its noticeable thickness.

IMG_20190622_113631.jpg
The Tektro Type 17 mated to a Magura MT5 caliper.  Once again note this caliper is bolted straight down onto its adapter and fitment to the rotor is essentially perfect.

Its worth noting both the Magura and Tektro rotors discussed here are generally too thick to use with normal brake calipers.  Not so with the MT5’s.  And if you are guessing the extra-thick, never-warping rotors are going to last longer, you’d be guessing right.  the rotor above on the orange bike… so far I can’t seem to wear it out.  That bike is my daily driver and I can’t measure any wear after about a year installed.  I have worn out a set of the Maguras, but it took thousands of commuting miles.

Thats nice.  How Much?

So all this is wonderful.  What did I spend?

I’ll give you a couple different answers on that.  On every bike of mine but the Mongoose, I used the Magura MT5e brakes, which include a safety cutoff that wires into the BBSHD via the brake lever.

Here’s what an MT5 versus an MT5e lever looks like:

Note: the comparison above is deceptive as the MT5e lever appears the same size as the MT5 on the left.  It ain’t.  The ‘e’ lever is actually a fair bit larger.

Thats the only difference between the two brake sets, but its kind of a big one.  First of all, the MT5 lever on the left is often cited as feeling cheap or unsubstantial.  I do not find it so, but I understand where the sentiment comes from.  Most riders who use these do so on singletrack MTB’s where there is a lot of banging around, over and up against things.  On a street bike this need for durability – and bend-ability – is not so much a factor.

The lever on the right has the obvious connection that leads to your motor, so that when you depress the lever, your motor power cuts off for safety.  This lever is also constructed completely differently.  Its larger, made of alloy and its shape is much more… substantial.  Also note the metal pin in the middle of the lever itself.  This is a hinge.  It allows you to gently touch the lever and activate the cutoff while not activating the brakes.  This can be handy if you are using the brakes as a sort of clutch to cut the motor out during shifting (the reasons for doing this are discussed here).  This second hinge also gives you a surgeon’s precision when modulating brake pressure.

Currently as I write this in October of 2019, the cheapest source for MT5 and MT5e brakesets is here.  This is where I bought the MT5 brakes I have on the Mongoose.  I have also bought MT5e sets here in the past.  Note that while this is a web site in Germany, and you will have to pay shipping charges, they are reasonable and the prices are so low you still save money.  Especially if you get a few sets of extra brake pads, which are roughly 1/3 of what you will pay for the same name brand pads in the USA.

If you are using the MT5e levers with the cutoffs, then you also need an adapter to mate their red HIGO/Julet plug to the yellow one on the Bafang motor used in this project.  Those are found here.

Brakes (two options)

  • If you are just going the lowest cost, max-functionality route like I did, you’ll pay about $150 for a complete set of brakes (MT5 only).
  • If you instead go with MT5e’s (you must select the version that is “Normally Open” a.k.a. “Closer”) you are looking at around $100 per axle at the above German web site.  $125 if you buy from a USA dealer (I like Planet Cyclery on EBay – they are a Magura dealer and performed a free warranty replacement for me a year after a sale).  Add to that about another $30 for the cutoff adapters.  So about $280 total.

Brake Caliper Adapters

Adapters for the rotors are going to run you $7 to $10 each.  I used 203mm rotors front and rear so a Magura QM9 / ISH-203 in the rear and a QM5 / ISF-203 in the front.  Buy these with your brakes and pads and save the shipping cost.

Rotors (two options)

I am only listing two options here in case you cannot get hold of the Tektro Type 17 rotors.  Make sure they are specifically the Type 17 as Tektro makes other rotors that look almost exactly alike and are very common on the marketplace, while the 17’s are relatively rare.

  • Magura Storm HC rotors are meant to work with these calipers and do so just fine.  They are available for about $21 at the same source as above, and at many other retailers for only a little more.  The only reason I don’t use them anymore is I found something better…
  • Tektro Type 17 rotors are only regularly available from two sellers I am aware of, although I am certain there are more out there.  The first is from seller hi-powercycles and is where I buy all of mine.  The second source is at Empowered Cycles.  Empowered also sells the Type 17 in a 180mm size, so if for some reason you decide you need a smaller size, they can sell you one.

Replacement Pads

You have two choices, but if you are smart, there’s only one you should pick

  1. MT5 pads (Magura Type 9) – These 2-piece pads provide a single surface for the two caliper pistons to press into.  They do provide excellent response, but the type 8’s are … more better.  Plus in order to remove Type 9 pads, they have to come out the bottom of the caliper.  You have to remove the caliper from the mount to make that happen.  More work for you.  Unless for some reason you decide you want to use the Type 9.C Comfort pads (hint: you don’t) there is no reason to use Type 9 pads past using up the set that comes with the new calipers.
  2. MT7 Pads (Magura type 8) – These 4-piece pads are better in every way than the Type 9.  Most obviously, they can be removed from the brake caliper from the top, so you just undo the screw-in retaining bolt, pull the pad out with your fingertips and slide in a new pad (they set nice and easy thanks to ingenious magnets inside the caliper).  Not so obvious:  the independent Type 8.P pads have been measured to add a significant increase in clamping torque to the rotor.  They also come in a Type 8.R pad, which has a sintered pad compound.

Whats the Down Side?

Just one:  You will have to learn how to cut and bleed brake lines.  Honestly… its easy to do.  But you will have to do it.  Check out the videos at the bottom of this post.  They are what I used to figure it out.  You will need a bleed kit to get the job done.

HOWEVER…

You can cheat.  Each brake set comes with 2200mm of cable, pre-bled and fully operational.  Just use it.  Run the cable, then loop the excess and stuff it into a handlebar bag.  There’s a little for the rear and a lot for the front.  I added a front rack and the little bag I have on top is where my extra cable went.  Its kind of disgusting how well it works and how its so low key I could get away with just leaving it like this forever.  But it is definitely a lazy kludge.  I’ll do the job right some weekend or evening this winter.

Performance

ummmm.  Awesome!  Duh…

  • They are not grabby.
  • You never have to squeeze hard.
  • They don’t fade.
  • There is always more brake available than you need.
  • They are silent (the sound of Magura pads on a rotor is sometimes referred to as “blowing bubbles” and this is actually accurate.  I’ll leave it to you to experience what that actually means for yourself.
  • The pads never need adjustment.
  • If you use the MT7 pads, you replace the pads without removing the caliper from the bike (and you also get a lot more clamping force as a bonus).  But since the MT5 pads come with the calipers for free, use them up.
  • The lines do not leak.  I have heard of hydraulic brake systems that leak fluid and Maguras … don’t.
  • These brakes use mineral oil rather than DOT hydraulic fluid… thats a big deal because DOT fluid is nasty stuff… corrosive to paint just for starters.  Mineral oil, on the other hand, is harmless.

Mongoose – Chapter 7 (Build Sheet)

I’ll try and keep this as simple as I can and simply list parts in what passes for a table in basic WordPress which does not support tables.  Over time as this project is filled out the reasons why I chose what I did will be covered in the various articles

Mongoose Envoy Bike               Amazon              749.99
Ursus Jumbo Superduty kickstand   Amazon               79.99
Jones H-Bar SG Loop Handlebars    Jones Bikes          79.00
Jones 205mm Kraton Soft Grips     Jones Bikes          20.00
Magura MT5 disk brake set         bike-discount.de    137.00
Thudbuster LT 27.2 XL             Amazon              119.99
ISH-203 203mm rear disk adapter   bike-discount.de      6.86
QM5 203mm front disk adapter      bike-discount.de      6.86
Tektro 203-17 downhill rotors (2) ebay (hi-powercyles) 42.40
Continental Contact Plus City     Amazon               69.54
   26x2.20 tires (2)
Sunlite thornproof 26x2.35-2.50   Amazon               33.90
   Presta valved inner tubes (2)
BBSHD motor kit                   Luna Cycle          699.95
   68-73mm standard motor
   Mounting hardware
   wiring harness
   speed sensor
   basic crankarms
   Luna 500C mini color display
   Universal thumb throttle
Second Bafang inner lock ring     Luna Cycle            5.95
Battery Solution
   Wolf V2 52v 12ah battery pack  Luna Cycle          549.95
   Potted, QD mount, 50a BMS and 
   Samsung 30Q cells
    -OR-
   52v 12.5ah battery pack, basic Bicycle Motorworks  369.99
   pack construction, 50a BMS and
   Samsung 25R cells
Luna Eclipse chainring            Luna Cycle           99.95
   Anodized black face                  
   Anodized gunmetal chainring
Lekkie Buzz Bars (crankarms)      California-ebike     99.00
SRAM EX1 144Lnk mid-drive chain   Amazon               28.99
 -OR-
KMC X9.93 (7 feet - more links)   Luna Cycle           57.75
Shimano HG400-9 12-36T cluster    JensonUSA            25.99
 -OR-
Shimano HG400-9 11-34T cluster    Amazon               24.60
Shimano RD-M591 9spd derailleur   Amazon               40.16
MicroSHIFT TS70-9 shifter         Amazon               23.99
ROCK BROS Wide Platform Pedals    Amazon               21.99
Raised rear deck
   Moose Skateboard Deck          Amazon               28.95
   aluminum unthreaded spacer     McMaster-Carr        10.88
      13mm OD, 25mm long, for 
      M5 screw (qty 8)
   countersunk M5 wshrs (qty 10)  McMaster-Carr         4.84
   stainless hex/flat head screw, McMaster-Carr         9.35
      M5x55mm (qty 25)
Front Rack
   Axiom Streamliner Front Rack   Amazon               47.99
   Delta AxelRodz skewers         Amazon               13.60
Wheel Build
   Sun Ringle MTX39 26", 30mm     Amazon              126.00
   Internal, 39mm external width 
   32H downhill rims (qty 2)
   DT Swiss 350 Classic Hybrid    Amazon              249.00
   rear hub, 148mm Boost, 32H 
   QR end caps for DT hub         Local Bike Shop      35.00
   Shimano HB-M475L front hub     Amazon               37.43
   DT Swiss Alpine spokes         Local Bike Shop     250.00