Frankenstein Boots For The Ursus Jumbo

I had an aftermarket kickstand that was too short. Here’s a way to add a tough-as-shoe-leather extension that should last forever.

My Mongoose Envoy received a much-needed upgrade to its kickstand when I upgraded to an Ursus Jumbo, whose much-wider (18″) leg platform keeps the bike stable on uneven pavement or when it was heavily loaded.

The stock Envoy stand works well unless you have 100 lbs of groceries loaded up. Do that and .. oops you gently bumped the bike! Over it goes and boy does your life suck. You’ll have to unload the bags, stand the bike back up, uncrack the eggs and load back up again. Same deal happens when parked on an incline.

The Jumbo solved this problem given its obvious mechanical advantage.

Jumbo on… Skinny tires. Problem solved.

… until I put some big poofy 26×2.8 Vee Speedster tires on the bike, which raised the frame up probably a full inch; maybe more. That meant of the two legs that Ursus kickstand has, only one of them was on the ground at any one time. At first it was kind of fun to be able to lower the stand and roll the bike around, or out of my way with ease. Then I saw what a bad idea it was on a sloping driveway. The bike was happy to tip over. For a cargo bike that will be loaded, that has to change.

Fat tires tall. Fat tires good. Kickstand barely touching ground bad.

A couple of methods presented themselves. The first was to lower the stand by shimming the base. While I would have been able to find a longer M10 bolt to do the job, making a shim that will actually work is a lot more complex than just throwing in some washers and calling it good. Absent a mill and some billet to do some custom fabrication, shimming was a no-go. So, since I can’t make the base longer, that leaves only the legs. I had to make them longer.

Shoe Goo… To The Rescue!

I should be brought up on charges for that header. Couldn’t help myself, and besides its true. Shoe Goo is a shoe repair tool that is essentially replacement shoe leather. Or shoe adhesive to hold your precious Converse All Stars together after they came apart. Or both. For you shade tree mechanics, if you think of it as a hard rubber equivalent of JB Weld … you have it down.

I suggest buying the big tube. I used about one full tube per side.

So what I decided to do is to stick my kickstand upside down in a vise, block off the bottom of each leg with some painter’s tape, fill the resulting cup with goo and let it dry. Peel off the tape and I’ll have a longer kickstand with a new, tough-as-nails rubber foot.

It turned out to be a bit longer than that, and took quite a bit more time to cure. But layering on a bunch of goop to the bottom of the kickstand is the short version of what I did here. And best of all, it actually worked.

Time For Plan B

What you see above is only the first attempt, using green painter’s tape. And while it worked (see photos sans tape) it became clear just by looking at it I could expand the ‘foot’ to a much greater size if I taped off the base and poured in more goo. You can see this in the last two photos where the tape has been removed. the foot of the Jumbo has essentially a large hole in it that you can further tape off, then fill in. this time you need to tape halfway up the leg as that hole runs thru to the front of the stand, and your tape will provide a deep chamber for the goo to fill and harden into.

This time I used silicone tape, which I discovered by accident does not stick to Shoe Goo! Knowing that, I was able to use a scrap of tape to help sculpt the slowly hardening-but-still-pliable glob of goo. That matters because as this stuff dries – and then cures – it shrinks into itself. You will need to come back every couple of days to apply another layer. And when at some point you call the job done, you will want to let this material sit for at least another five days.

So if you are doing the math here, that means this is going to take time. I spent a total of about two weeks applying, filling again after it shrinks down and then letting it cure so its stable with a bike standing on it.

Is it worth the trouble? Well, I spent about $8 on two of the big tubes of goo and another nickel or so on a length of black rubber mastik tape around each foot to pretty them up. When I was done, I had a kickstand that completely solved my problem, and I can expect to be able to use for the life of the bike. If you want, Shoe Goo comes in a black formula that will have a matching look… but it costs more than double what the clear stuff does.

If You Do This…

I felt my way thru this project and learned as I went. The way YOU want to do it is skip the first stage with the green tape entirely. Use the silicone tape to wrap the entire foot. Wrap snugly at the bottom of the channel you want to fill, and as you get to the top – the actual extension to the base – do not wrap that tight, just do it loosely and make sure the tape wrap adheres to itself. Then inject the goo with a narrow nozzle (there are kits out there that have them) deep into the channel you just created, filling it from bottom to top until you have a single large ‘sole’ wrapped in the silicone tape.

Then, walk away from it for 24 hours. Add more goo as it cures and shrinks down. Use a scrap of silicone to pat down the added goo so it forms a nice smooth surface. If it seems solid, remember thats just the outer layer and inside its still like jelly. I went on a week’s vacation after I thought I had it done and it was pretty solid.

So… Wait it out. the results are worth it.

Mongoose Envoy Update – Cargo Deck 3.0

When I originally used a double-kick longboard deck to make an XL cargo carrying top for my Mongoose Envoy project, its 33″ (84cm) length and 10″ (25cm) width seemed really big.  Considering I was coming from a world of ordinary bike racks on normal-wheelbase bikes, it was quite large.

img_20190929_170059
Deck 1.0, shortly after installation. I try to avoid the word “festoon” to describe a bike build so those two little bags in back went away soon afterwards.

The XL deck worked *splendidly*.  I had no complaints whatsoever, and I could have left it like that forever.  However…

The board, by virtue of its 33″ length, only used 4 of the 5 available rows of M5 mounting bosses.  So I had definitely left some available space on the table.   In a perfect world, I would have found a longer version of the same board:  Say a 40″ double-kick.  But alas, at the time, I couldn’t find one.  I also could not find another board that had this same 10″ width.  Everything else was more narrow.  But I could get close with what became Deck 2.0: a 40″ x 9.75″ kicktail longboard.

It installed easy enough.  I painted it with Rustoleum truck bedliner to pebble the surface just right so it held onto gear a bit.  I used the same inverted grub-screws for drill guides like I describe in the Deck 1.0 post.   And the rack was now long enough so it used all 10 mounting points on the frame.  It couldn’t be more solid – the board is 8 layers of Canadian maple – and makes a sturdy handle I can use to pick the bike up and move it around from the rear.

And… its 40″ long.  With that solid center mount kickstand, its handy to have a coffee table with you wherever you go.  From a cargo standpoint I could easily net down a 3-foot duffel bag on top and still have room to spare.

Still, It didn’t work out quite the way I planned.  I thought I wanted to move the rack further forward so I could mount gear under the seat.  So I did that and the idea was to take up the otherwise wasted space just behind the seat.  But once I had it set up, I found the space effectively unusable.  I needed to keep some room back there for the Thudbuster to flex as part of its normal duty cycle, and my legs hit whatever was jacked up all the way to the front.

I also missed the front kick on Deck 1.0, which provided a natural slope to keep gear from sliding forward under hard braking.  As a substitute threaded a couple of M6 bolts directly into the M5 holes (no fixing nuts needed) that existed for the nonexistent trucks. These held down a simple 50-cent L bracket wrapped in my favorite padded rubber mastik tape.  It worked but in the end I removed it for aesthetic reasons. 

Lastly, I mounted the board just a hair too far forward, and occasionally I brushed it with my legs during the pedal stroke.  Not a big deal unless you are a perfectionist. I didn’t want to redrill the holes so I could move it back. It was a minor imperfection. So I left the board on for several months and it worked great.

But I did acquire a 44″x9″ kicktail longboard from Magneto, with the intention of using it on the back of a planned Surly Big Fat Dummy build.  That plan went away, and the 44″ board had no home… so what the hell lets put it on the Envoy.

While I was at it, I decided to make a couple of changes.  First of all, the Magneto board comes with an aggressive, highly abrasive grip coating on it.  I took an orbital sander and smoothed it down some so it would not potentially wear thru duffel bags and bits I’ll have netted down on top of it.

Next, I painted it with the same Rustoleum truck bed coating spray.  This took a little more of the harshness off the grip coating and gave the deck a tough finish.  I also decided to two-tone it with some medium gray paint on the underside.  It turns out this is totally invisible unless you are laying on the ground looking up at it.

Also, instead of re-using the 25mm post spacers, I bought new ones 40mm tall. These required longer 75mm bolts.  Having used the rack already for several months with 25mm between deck and frame, I wanted more room to move my hands in and out attaching/detaching net hooks, passing cinch straps thru etc.

It came out great.  This Magneto board is a sandwich of bamboo and maple so it has a touch of flex to it. This made  bolting to the somewhat uneven frame easier.  Its still rock solid despite the now 4″ longer tail out the back, which I do not notice from a convenience standpoint (its not too long, which I worried about).  The 40mm spacers are an absolutely perfect height to let me get my hands in there without being so long they compromise the solidity of the mount.

The board has a front kick, but it turns out it can’t easily be used, for the same reason I couldn’t use the front few inches on the 40″ deck. However it is slightly narrower than the shorter board so even though it is just as far forward, I no longer hit it with my legs.

As a gear-stop/bumper, I wanted something a bit more substantial than the half-assed L bracket I used on the shorter board, so I used a couple of the leftover 25x13mm M5 spacers, plus some 10x10mm spacers I had in my parts bin, to create some ‘electrode’ stanchions fore and aft.  With the large area washers at top, they either provide a bumper for gear stowed on the deck, solid purchase for a hook, or a place for my net to grab onto in the very back. Silicone grip scraps fit right over them to ensure the edges of the top washer don’t bite into my gear.

The two forward stanchions are extended from the deck mounting holes and go all the way thru to the frame.  They use 110mm M5 bolts.  The two in the rear use the rearmost holes drilled for the trucks. These use matching countersunk bolts and finishing washers like those used with all the other mounting hardware.

img_20200514_163026
A bit of scrap silicone handlebar grip tucks under the rear stanchions to provide a smooth, grippy place for my net to glom onto. You can stretch the net all the way back and over the kicktail, too.

Compare this pic above to the 40″ board and its clearly longer, but functionally, the increased length is no bother.  If I had to fit the bike on a train or bus then this is not the best solution.  At some point, if I need some extra carrying space out back, its available.  At present, I have an extended amount of space for my round 40″ duffel.

… and a bigger coffee table.

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.

Mongoose – Chapter 9 (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).  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 7 (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 in the rear, 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 8 (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



Mongoose – Chapter 4 (Motor Choice)

I have chosen a mid-drive as the best tool for the job on this bike.  It will not only be hauling cargo, it has to be able to do it in a steep hilly area.  If I was building for flat ground, a maintenance-free direct drive hub around 1.5-2kw would be the answer.

I’m not doing that though.  So mid-drive it is.  Now, which one?  there are plenty on the market and I have owned and in some cases still own several different ones.

Originally when I was planning this article, I was going to describe all of the major players in the market, and why I chose the one I did.  Instead I’ll limit my scope to the top two choices to better stick to the subject.

Second Choice: Bafang BBS02

This should be the first choice for most people.

I do want to say that as far as I know, as Bafang’s largest USA dealer, only Luna Cycle sells a BBS02 I would want to buy.  Luna uses their buying power to spec more robust controller internals that keep the BBS02 from frying its controller under sustained load … that was something of a known drawback of these motors in their heyday.  Also, Luna’s pricing strategy means their BBS02 kits are among the cheapest, if not *the* cheapest, BBS02 on the USA market.

Bafang mid drive motor kits are at the bottom of the the difficulty curve in terms of installation.  With one of these, you can have a bike up and running in an afternoon.  You’ll find a zillion Youtube videos and blog entries telling you what to do and how to do it, as well a multitude of experienced users in online communities ready to help you through whatever specific, quirky question you may have.

bbs02

Sidebar:  Bafang is a mainland Chinese motor manufacturer that is essentially the 800 lb gorilla of ebike motor manufacturers.  If you think companies like Bosch are market leaders, their volume is a fraction of Bafang thanks to their massive installed base in the Far East.  Bafang motors, while not perfect, are typically overbuilt, rugged, dependable and not very exciting.  Workhorses.  Chinese products have a reputation for ‘optimistic’ spec sheets and shaky quality.  Bafang is pretty much the opposite of that.  They underreport their motors’ capability – It seems one reason for that strategy could be so they can sell the same motor with different power ratings, with a higher price point for the ‘bigger’ one.  Again they are not perfect by any stretch, but for the beginner, working with a USA dealer of their products (do NOT be tempted to buy cheaper from an overseas vendor), its hard to go wrong.

The ’02 has been around for awhile, and what is sold as the ‘BBS02’ in the USA amounts to Bafang’s first effort at a kit offering (you can still buy BBS01’s – mostly overseas – and they are essentially a low-power BBS02).  It has long since been eclipsed in terms of power, and its aftermarket support for upgrades is not what you find for its successor, the BBSHD, but still the ’02 remains a rock solid product (IF you heed the caveats above).

A 750w or 1000w ’02 would have been my motor of choice for this project, except I already own two other BBSHDs.  As such I decided to keep one set of common parts across the fleet, so to speak.  I went with the more powerful next generation: the BBSHD.  More on that below.

Another Sidebar:  If you see these motors with the label ‘8FUN’, thats Bafang’s house label.  Usually those motors were manufactured for sale overseas in the Far East.  You can also find BBS02’s and BBSHDs with private labels on them.  Thats common.  Bafang will sell a private-labeled motor to anyone who will give them a big enough order.  Some vendors – like Luna Cycle, Bafang’s largest USA dealer – private-label and sell at a competitive price to builders.  Others just add their own label and crank up the price.

First Choice:  Bafang BBSHD

Bafang updated the BBS02 with the BBSHD (its called the BBS03 in some overseas markets).  The ‘HD is essentially more of everything you get in the ’02.  More robust.  More aftermarket support.  More power.  And more money.  But its still a bargain, with a bare motor running around US$450.  A complete kit providing you with everything you could ask for, plus programming upgrades (Bafang motors have a robust capability to customize their behavior, ranging from total power output to precise tailoring of each of the 9 pedal assist levels). should run you about $750 before you get to the battery.

bbshd

Myself, I paid less than that simply because I already have two other bikes that use this motor, and I have quite a few spare parts on hand.  I can just pick stuff up off the parts pile for zero added cost.

Stealth

You’d think this motor sitting in front of the bottom bracket like a giant wart would be obvious to people, but it turns out it isn’t.  Oftentimes, I get asked “Is that thing electric?” and when I point out the motor I see the questioner’s eyes light up in surprise.  So visibly it doesn’t stand out to people.  Especially since I keep the battery in a triangle bag – not to keep that part stealthy, but because that makes it easy to haul out and carry into the store with me.

The next component of stealth on an ebike is sound.  How loud is this motor?  To all intents and purposes, the motor is completely silent.  If you fire it up on the workbench, they definitely make an audible whirring electric-motor noise.  But on the road, even at the slowest speeds with no wind noise in your ears… you’ll be lucky to hear a slight hum.  And anyone next to you – like that poor sap you cruise by while he struggles up the hill in his analog bike – they won’t hear anything either.

Mongoose – Chapter 3 (Motor Types)

I am making a particular choice with regard to the motor I am putting on the bike that is the subject of this series.  I’m familiar with the various types – their strengths and weaknesses – but for the sake of the reader who may not be, I’m going to do a quick-and-dirty on each mainstream type.  If I’m not covering that motor type (looking at you, friction motors)  there’s a good reason that further research on your part will reveal.

There are three types of motors that make it into the mainstream of the ebike world

  1. direct drive hubs
  2. internally geared hubs
  3. mid drives

Direct Drive Hub Motors

mxus.jpg

DD hubs work with no moving parts and are effectively maintenance free.  The axle of the bike is also the axle of the motor itself, which is just a brushless DC motor with magnets running around the outer case of the motor (the rotor), copper windings wrapped around the interior stator etc.  Apply electricity and the stator repels (or attracts) the rotor, which results in the rotor spinning, and there is your powered motion.

Relative to the other motor types, DD motors produce much less torque.  That means there’s not much oomph behind the motor and you either help it along with a lot of muscle if you want acceleration, or you sit back and wait for it to spool up (in a worst case scenario you are hoping to get to the other side of the intersection before the light turns red again).

To get around that lack of torque, you use a really big motor and a really big, powerful battery.  Once you get into the 3kw-5kw and greater range, with a 60v or higher voltage battery, now you are talking about a bike that is accelerates acceptably (or insanely depending on how big you went) and can climb hills easily, even loaded with extra people and groceries.

The drawback to the above is that big motor, with its big metal magnets and large amounts of copper wiring is … big.  Heavy.  And so is the 2XL battery you needed to get big power out of that motor.

For a serious bike that can carry cargo, passengers etc. up a hill at speed, you are probably talking about a 125 lb bike, with a lot of that weight inside of the back wheel.  The battery is likely going to be on your rack as well (not your cargo) reducing your carry capacity.  At lower power levels (particularly those that are less illegal than the above noted 3-5kw) you aren’t looking at that kind of weight penalty.  But you get low performance as a result.  A direct drive motor that is not in the hi-power league will need a long run-up to get to cruising speed.  And if you want to climb a hill… well its the worst choice for that job of the motors you can choose from unless, again, you go big.

If you want to research the ins and outs of this type of motor further, you need to also look into ‘torque arms’, why they are needed with this kind of motor, and when.

Geared Hub Motors

Geared hub motors do a good job of providing more torque than DD hubs at similar power levels.  They do this by installing a planetary gear reduction inside the motor which connects the stator to the outer casing.  The motor spins nice and fast as it likes to.  The axle in turn spins the planetary gear.  This finally turns the outside casing and the wheel at a slower speed, so you and the bike can go down the road at a comfortable rate of acceleration.

img_20180704_054016
I opened this motor up for its semi-annual re-grease.  I also needed to deal with that rust you see.

Geared hubs tend to be lighter than their direct drive cousins, which helps with range and acceleration.  At sufficient power levels – lower ones than what a direct drive motor needs to do the same job – a geared hub gives some pretty good torque.  80 Nm in the case of the above pictured motor.  Mate that to a 35 amp controller and a commonly available, medium-voltage 48v battery and you have a really peppy ebike.

Whats the down side?  Those nylon gears will take a lot of abuse (really a lot), but they won’t last forever.  Especially if you subject the motor to regular extended hill climbs, or you are subjecting it to a lot of stress… like a full cargo load.  If you try to solve this problem with steel gears (Chinese Ali Express specials that may not have been the best re-engineering job) you find out why motor manufacturers use nylon:  noise… and metal shavings.

You will also have to open those motors up every few thousand miles and re-grease them, as the grease perishes over time.  Lastly, geared hubs really do not exist at the higher power levels (most I have seen are the MAC motors peaking at around 1500w with a special controller to get them up that high).  Any higher than that and the gears really can’t handle the power.  Unofficially, A Bafang G060 fat motor like in the picture above can handle a 60v battery and 35a controller that delivers 2.2 kw peaks … forever.  But I wouldn’t bet my motor’s life on it being able to do long term that under severe loads like cargo duty or living in steep hills.

Final thoughts on hub drives

Both geared and direct hub motors power your bicycle directly through your hub axle.  They are the hub in fact.  What this means is, your bicycle powertrain is entirely irrelevant to what the motor does.  The power to the ground is transmitted directly from your axle.  In fact, if you want to have some fun with your hub bike, you can remove the chain.  Then ride down the street with your pedal assist turned on, and pedal the bike.  It will work just great.  Of course you aren’t getting any exercise and likely you don’t want to ride like this, but it illustrates the fact that the traditional bicycle powertrain is not needed.

Your pedals and chain now exist almost solely to provide you, the rider, with exercise.  You put as much effort into pedaling as you want, and that can be just mild pressure or pushing hard the way you would riding an analog bike.   It is now the motor thru the axle that is doing the real transportation work.  This fact is not lost on ebike manufacturers, and this greatly reduced duty cycle means hub-based ebikes tend to have cranks, chainrings and rear clusters that would not survive long if given the hard life an old-school analog bicycle receives.

Geared hub motors need torque arms just like direct drive hub motors, albeit not so much at the lowest power levels (i.e. 250w and 350w).

Lastly, both types of hub drives have this significant benefit:  they don’t require any special knowledge or care to use.  You can jump on the bike as a complete newbie and start riding.  So long as you aren’t riding some kind of hot rod that is hard to control, you already know everything you need to ride happily down the road and not cause any issues.  That makes hub motors of one sort or another preferred for most casual riders who are not challenged by their terrain.  That isn’t true of your more powerful mid drives, but I’ll get to that below.

Mid Drive Motors

‘Mid drives’ are known as such because the motor sits at the middle of the bicycle.  Typically replacing the bottom bracket.  As much as hub drives dominate the lower-cost, DIY and upgrade ebike markets, mid drives dominate the big-name commercial-manufacture market.  In particular, and most telling as to the benefits of the mid drive, E-MTB’s are exclusively mid drives, and for good reason.

img_20190603_194127
Yes, this is an ebike (and yes, its mine).  Look closely at the chainring.  See the mid drive motor hiding behind it?  This motor peaks at around 440 watts of final output which in the USA is well under the legal limit.

Mid drives work on an entirely different principle than hub drives.  Hubs, as we noted above, power your bike thru the axle, and your drivetrain is just along for the ride.  In terms of assistance, the hub drive bike is a 1-speed, and this is part of the reason hub drives don’t do so well in hills or fast acceleration, unless you start getting into big power.

But a mid drive works just like you do:  It pours on the power thru the bicycle chain.  That means if you hit a hill, you can downshift into a lower gear, keep the chain spinning fast and get up the hill more easily.

Gee thats great.  And since much of the world has legal limitations to 250w of final drive power, you can’t really put enough power into the system to break anything.  An average person in good shape can put between 50 and 150 watts of power into their drivetrain during a ride.  Thats what an old-school analog bicycle drivetrain expects to put up with.  250w isn’t a whole lot more than that (a trained cyclist can pour on roughly 400w or so… and sprint briefly up to around 1500w… which is still not really enough to make a slice of toast).

About that 250w limit… First of all, here in the U.S. that number is typically “less than 750 watts” according to our national manufacturing/consumer safety standard.  Many of the individual U.S. states have vehicle codes that separately define what is an ebike vs. a moped vs. a motor vehicle.

Beyond that, in the last year or so we’ve started to see rebellion from major E-MTB manufacturers against the almost-a-joke 250w EU limits.  What we are seeing is the complete disappearance of any mention of wattage output.  Instead all you see references the Newton Meter (Nm = torque) output of the motor.  Unstated is the *ahem* potential for the motor putting out more than 250w.

Really, torque output is what matters in terms of figuring out how much assist you are getting, and mid drives just pour on the torque.  A Bafang BBSHD, the de facto volume-sales king of the American DIY market, puts out 160 Nm continuous torque when it is fully utilized.  That is about double the momentary peak of what the big geared hub pictured above is capable of (and that geared hub is among the biggest of its genre).  Direct drive hubs are in the 40-60Nm range unless you go all Mad Max on the power levels.

So … easy choice everyone needs a mid drive!  Well, not so fast.  With great power comes great responsibility repair bills if you don’t use your head.  That means build it right and learn how to ride it.

Remember the wattage output a normal human is capable of?  The level that a quality drivetrain is expected to be able to handle?  Well, the above referenced BBSHD in off-road mode, pouring out those 160 Nm, is feeding about 1500-1700 watts to the drivetrain.  Continuously.

You want to figure out how much wattage is going to your motor?  The formula is Volts * Amps = Watts.  So a 52v battery running at its nominal 52v rating, multiplied by a BBSHD running at 30 amps is… 52*30=1560 watts.  At a full charge that battery is 58.8v, so 58.8*30=1764 watts.  Continuous output.  Yes, really.

So, when we build a DIY mid drive bike, we first want to buy parts that are meant to take this kind of punishment.  They are out there on the market but frankly a lot of DIY builders, riders and even most ebike sellers are ignorant of this.  You want:

A good narrow/wide front chainring

Made of 7075 alloy most likely, but if you can get a steel ring, do it (Wolf Tooth is the only one I know of and they only come in 30T and 32T sizes).   This style of ring typically has wider, taller teeth that eliminate chain dropping issues.  In particular rings made specifically for mid drives are sold by Luna Cycle, who manufactures their own here in the USA, and Lekkie, a New Zealand company with a stellar reputation who sells thru ebike vendors everywhere.  The latter two names are focused primarily on the BBS02 and BBSHD markets although Luna does make rings that will work on other platforms.

An ebike-specific chain

The interwebs are filled with complainers crying about how their chain snapped.  When you ask how many of them re-used their $6 stock chain, or who just bought a ‘nicer’ bicycle chain, the numbers pretty much climb up around 100% of chain failures (chain alignment will be dealt with below).  E-bike specific chains in various widths for various speeds are sold by KMC (my favorite is the X9e/E9 9-speed) in 136 link lengths.  SRAM’s EX1 ebike group has its own 144 link chain.  Lastly there are the Connex chains by Wipperman.  The common factor in why people don’t use them (besides not knowing they exist) is price.  These are US$35+ chains (you can buy smart and get them for less if you know where to shop).  But… They.  Don’t.  Break.

Lastly, you can find a specialty vendor and buy a specific length of chain all in one piece, so you don’t have to section two chains together (if you do that, it creates a potential weakness at the joining point).  This is by far the most expensive option.   I bought a 7-foot length of 9-speed chain from Luna Cycle and it ran me about $60.  But my Mongoose Envoy, with the long-cage Deore derailleur I added, needed 152 links to be set up right (I keep a 144-link SRAM EX1 as a hot spare and it will work fine in a pinch).

kmc x9e.jpeg
The KMC X9E.  Those mushroomed pin ends will be torn off if you use a chainbreaker on them, so if at all possible just remove links to make it shorter, don’t add any to lengthen.  re-attach with master links.

A steel cassette cluster

You have two choices for this, generally.  First is the SRAM EX1 cluster that is an 8-speed, has a range of 11-40, is made of tool steel and meant to be used with the EX1 shifter which will only shift one gear at a time.  The rub is the cluster alone runs about US$385.  Its worth every penny (I have one on my E-MTB, so it had better be), but that cost is insane.  How about spending US$15-25 instead?  Just buy any cheap Shimano rear cluster.  In particular the HG-200, the HG-400 or the HG-50.  All in 8 or 9-speed.  They use steel, not alloy, cogs, and most importantly the entire cluster is welded together into a single unit so the punishment dealt to the cassette body is distributed across its entire width.  These Shimano clusters are an excellent example of something that is awful for an analog bicycle and highly preferred on an ebike, where durability is vastly more important than light weight.

Shimano-CS-HG400-9-9-speed-Cassette-silver-12-36.jpg
This is the 12-36T 9-speed cluster I am using for my Envoy build.  Don’t look for any bolt heads to allow disassembly.  Only the 12T cog is separate from the 1-piece body.

A steel cassette body

Here again, what sucks for a bicycle is great for an ebike.  A steel body will last.  An alloy one won’t.  Take a look below.  On the left is an alloy DT Swiss cassette body with about 1600 miles on it.  It comes from a DT350 hub, which is at or near the top of the line as bicycle component brands go.  The cassette cluster I used was a welded steel Shimano, so those notches you see still tore into it despite the gentler damage the welded cluster does.  I almost exclusively used the 11T small gear on this bike and on the far right you can see that section is torn into further than the rest (the last cog is free floating so no help from the welded together body on that one… we’ll come back to this and discuss further below).

bodies
eek… and this happened with a 1-piece cluster, too.  With a nicer cluster that has removable cogs, the damage would have been much worse.

 

On the right side is a steel version of that DT350 cassette body.  Unlike the alloy version, it is much heavier – and I expect it to last forever.  Worth noting:  DT Swiss has now released a “Hybrid” version of the 350 hub specifically meant for ebikes.  It includes the steel cassette body out of the gate as just one of its durability improvements.

Get a ‘star ratchet’ rear hub

There aren’t many of them.  DT Swiss, Chris King and Hope are the only big names that sell freehubs with this sort of splined engagement instead of the traditional 3- or 4 pawls.  A splined engagement provides dramatically better contact with the hub from the cassette.  See that nearly-ruined cassette body above?  the stock 18-tooth star ratchet wheels inside went right back into the bike with the new steel cassette body… they were still perfect.  Since DT’s patent on their system ran out, other makers have begun to use it and you can now find star ratchet replacements and complete hub systems on Ali Express, EBay etc.  Myself, I still buy DT Swiss 350’s.  But you can save hundreds with the Chinese hubs.

Uf26dd6f62c374343bc8c305ec79489f7R

Learn how to ride it

I mentioned this briefly above.  With a couple of narrow exceptions (don’t mash the throttle going up a long hill) you already know how to ride a bike that has a hub drive.  thing is, no matter how seasoned and smart you think you are, chances are excellent you are clueless on how to ride a mid drive.

Here’s the short version:  Keep the motor spinning.

Now the longer one:

Keep the motor spinning

Lug it and the torque that is pouring out of the motor will focus on tearing your chain apart, or taco’ing your chainring or rear cog, not to mention generating enormous heat (remember the nylon gears in a geared hub motor?  Guess what?  Mid drives use nylon gears inside too).  Even a BBSHD set to off-road power levels is not strong enough to tear up your cogs or chainrings.  But it can snap a chain that you are mistreating.

When coming up to a stop light, downshift.

Always.  Either that or stay in a gear that is in the middle of your cluster so that when you start up again, the motor can spin up quickly without any brutality being visited on the chain.

When coming up to a hill, downshift.

Always.  Can you guess why?  Thats right so you can keep the motor spinning.  And ‘coming up to a hill’ does not mean ‘already started up the hill’.  Anticipate and shift in advance of the climb.

When you want to go faster, upshift.

But wait until your motor is spinning fast before you do.

When you up- or downshift, NEVER do so under power.

Shifting while pouring huge watts into your chain is an ugly thing.  You will recognize your mistake the instant the result hits your ears.  It won’t kill the chain outright, but as you hear that chain smash from one cog to another you will know your bike hates you very, very much.

You can invest in a gear sensor that will protect you automagically from this.  It installs inline on your shifter cable and, when it senses the tiniest amount of movement, it cuts power for an instant.  The result is a safe shift.  I have them on one of my three BBSHD-equipped bikes and it works great.

But for the two I don’t, I just stop pedaling/freeze my legs, click-shift and then do a single crankarm rotation to seat the new gear at low power.  Result is perfect shifting and only a minor blip in pedaling rhythm.  But that is a learned behavior.

Others have perfected the use of the brake levers as a clutch where they only slightly actuate the lever.  This triggers the safety cutoff which in turn allows a safe shift.  If you are like me and you cheaped out and don’t have safety cutoffs, this won’t work.

Keep chain alignment as straight as you can

Mid drive motors tend to work in a lot wider range than humans do.  So you can leave the motor in a gear that would be too low for your cadence and let it spin away like crazy… it actually likes it that way.  So, this piece of advice is partly about how you ride the bike (i.e. what gears you let it sit in) but also about how you build it.  You really only need three or four gears in the middle of your cluster on a mid-drive-powered bike.  You want them to be the ones that let the motor spin fast.  You also want the cogs the bike is happiest to not be cockeyed, front to back (i.e. bad chain alignment).

On an analog bike you can get away with a lot, since you are only feeding back 150 watts to it.  Feed it 1500 and that sideways-skewed chain will become a saw and chew right through your front chainring and rear cog teeth.  Be smart when you build the bike, and learn in your first outing or two whether there are any problem gears you should stay away from.  There are all sorts of offset chainrings (and 1mm and 2mm shims) available for a BBS02 and BBSHD… they cost money, but spending that money now means not spending it later after you have walked home.

What happens if you don’t do some or all of these things above to install and use a DIY mid drive bike properly?

Well of course it means you go on the internet and blame the equipment.  Its not your fault you used the wrong components.  And its not your fault you didn’t know how to ride it.  Its the mid drive’s fault.

This is the secret message hiding behind a lot of “don’t buy a mid drive” posts on the interwebs.

… If you build with appropriate components, and ride it smart, even a high powered mid drive will essentially last forever.  Yeah sure you will wear out the chain and rear cluster in say three thousand miles, the smallest cog in half that, and the chainrings in 10.  But thats peanuts considering how many miles you put on the bike.  How much does an 11T cog cost (about $6)?

Wrapping it all up

Whew that was a lot of typing.  This article lays out in broad terms the characteristics of each motor type.  It doesn’t get into what kind of riding each is good for.  Lets finish with that:

Direct drive hubs

  1. Lower/legal power:  maintenance free cruiser bikes for paved streets where speed and acceleration are secondary to bulletproof reliability.  Want a bike for Mom?  Your kids (who aren’t future BMX pro riders) A direct drive 250w-750w hub motor is a viable candidate.
  2. High power: Sky is the limit in terms of power:  Light electric motorcycles only thinly disguised as bicycles.  Can range across a wide variety of cycling genres including cargo, dirt and pavement.  But big and heavy.  Single speed is usually a bad choice for offroad/singletrack riding but there are exceptions, in particular the famous B52 Stealth Bomber and similar.  They have so much power they use brute force to overcome the weight issue.  But you’d never pedal one of these things.

Geared Hubs

  1. The Swiss Army Knife of motors.  Not ideal for anything but good for almost everything.  Only runs into trouble under very heavy use, particularly in an area that is all hills.
  2. Their only drawback is maintenance if heavily used.  Semi-annual teardowns to re-grease a high mileage motor is advisable.
  3. Bad choice for singletrack/offroad.

Mid Drives

  1. Best choice for singletrack/offroad
  2. Got hills?  Mid drive.  Strong power delivery without significant weight added to the bike.
  3. Good for hard-use applications.
  4. Arguably the most efficient in terms of power consumption.
  5. Requires the most attention to build detail and demands the most attention and learning from the rider.
  6. Even with proper use and components, more wear and tear on the drivetrain than any other option.
  7. A kid who gets his right hand caught inside the chain of a mid drive is going to be named ‘Lefty’ from that day forward.

Mongoose – Chapter 1 (Raised Deck)

The Envoy’s rear rack is about 27″ long and 6″ wide.  For a cargo hauler, I wanted it to be able to handle more.  The rear deck is very low over the back wheel, and thanks to my inseam, the seatpost is going to be set high.  Add all that up and you have a lot of available vertical room for cargo mounted on top of the rack.

We can do better than 6″ wide.  Especially since Mongoose has dotted M5 bosses seemingly everywhere on the rear of the frame.  I just did a quick count and saw 32.  And thats not counting the 4 additional lower rack bolts you can piggyback onto.  Also not counted are the 12 brazed-in hook mounts for the included panniers (that I’m only temporarily using due to their frustrating 6″ depth).  So what does that come out to?  This bike has 50 (fifty!) discrete attachment points.

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Visible here:  4 of the 5 sets of bosses that pepper the top of the rack.

This thing is begging for home brewed solutions so lets come up with one.  I don’t want just a regular deck on top of the rack, I want it to be wider than six inches so its a bona fide cargo platform.

My buddy Houshmand finished up his custom cargo bike build a few weeks ahead of me, and one of the things his framebuilder did was haul a skateboard deck off of his shop floor and decide it looked like a decent rack deck.  I agreed and informed my friend I would be stealing this idea.  So I did.

I started looking for a bare longboard deck.  I found decks as large as 48″x9.5″ for a dancer style, but it was something that doesn’t quite have that cool skateboard look I was going for.  I ended up settling on a 33″x10″ double kick deck that, while it doesn’t fully extend across the entire rack, its overall concave surface provides a sort of natural cradle for the duffel bag that will be cargo netted down to it.

The shorter 33″ deck also isn’t long enough to use all five sets of M5 bosses, but the four it does use it fits to perfectly.  Part of the concept I wanted was an overhang to the rear to ensure my back side stays dry if riding in the rain, and the board is bolted down to its most rearward flat location as a result.  Really it would not have fit well further forward or backward unless I shifted to the front four bosses and moved it quite a bit forward.

For hardware, I went to my old-standby for weird fittings: McMaster-Carr.  I know from previous projects they sell metric spacers in a variety of sizes and increments, and I had no trouble finding them in a wider 13mm diameter size.  However, my usual choice of stainless steel resulted in a hefty price tag.  I found they offered the same sizes in alloy which is perfectly fine for this application.

My original choice of 30mm spacers turned out to be problematic as well.  That size in 30mm x 13mm diameter isn’t stocked, so delivery is measured in weeks.  However, 25mm was available for next day delivery, and the cost per unit was about half what the 30mm’s would cost me.  Sold.

Ordinarily I will use socket caps on a job like this, but their squared-off and tall caps aren’t the best fit here.  I also did not want to mess with countersinking holes on the deck itself.  Besides, for durability I wanted metal to metal contact, not metal to wood.  In the end I decided on countersunk Phillips head bolts (50mm), with countersunk washers sitting on top of large-area stainless washers – the latter to distribute the clamping force across as much of the board as possible.  Under the board, between it and the alloy spacer, is another large-area washer to help further stabilize the connection.  Multiply this by 8, torque to a modest 4 Nm (the threads in a frame boss, which could be alloy themselves, are not the sort of thing you want to apply serious torque to) and you have something solid enough to sit on, that is completely rattle free.

After this article was written, I substituted longer, 60mm hex drive screws.  the added length gave me max thread engagement in the boss, and the countersunk hex head… looks nicer.

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Those bolt holes look a lot more even than they really are.  Thats the frame’s doing not mine.

Drilling the board to get the result above was a minor adventure.  I discovered quickly that the frame bosses were all, well… totally uneven.  You might be able to see a little of that in the picture above but I assure you the photo above is deceiving.  Its worse than it looks in the picture.  Trying to graph out a precise template that would then map perfectly to the board was clearly a Pain in the ass I didn’t want to suffer.  So I tried to think of a way to put something pointy in the hole so I could see marks directly on the board.  Stuff like finishing nails or similar just didn’t have the precision to sit perfectly centered in the hole.  And then I remembered grub screws.  “What the hell is that?” you ask?  Let me just show you.

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Behold, the M5x16mm grub screw made of the finest Chinesium. $7 for a bag of 16.

They were delivered to me next day by Amazon.  I chose the longest ones I could get my hands on so I would have plenty of thread engagement to get them to center up.  And they worked splendidly.  After I used painters tape to cover my likely drill areas on the deck, (helps keep the wood from splintering), all I did next was screw in one of these screws, pointy side up, into the outer four boss holes, I then gently centered the board atop them just right (I tried measuring frame overhang and in the end just eyeballed it) … and pressed down.  Instant markings on the board, and my drill holes are already started.

Next I drilled the four marked holes, flipped over the board and test fit the screws to the rack.  Perfect match.  Now for the four inners:  I screwed the board down with the four outers I just drilled.  This gave me perfect positioning on top of the four inner holes … which now had pointy grub screws in them.  This in turn pressed the board onto the pointy bits.  Once done, I again had a set of marks that were perfectly aligned with an installed board.  Using the new marks I drilled again and perfect fit again.  The rest was just inserting the rather fiddly combination of spacer and washer under the board.  

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On the road this new upper rack is rattle free, and so solid you can grab the bike by it and drag it around without worry

The end result works well I think.  I want the load’s center of gravity moved back a bit, effectively giving me a longer tail than I really have, for the top load, at least.  Additionally I still have a fair bit of unobstructed rack up front to play with.  When I put together my pannier solution, I have the option of using those standoffs, as well as what is now the ‘lower’ rack surface, for anchor points.