Great Big Bags (an important afterword)

Some time ago I made a post about Big And Cheap: DIY Cargo Bike Bags.  On that post I noted on the build sheet this last item:

Therm-a-Rest Classic Foam Pad        Amazon   29.95

And then never mentioned another word about it.  I still ignored it in the Cheap DIY Cargo Bags: Update follow-on post.

Oops

So, that item is actually sort of a big deal for these bags.  Why?  Because the padding lines the inside of the otherwise floppy ol’ canvas parachute bag and gives it a soft but firm structure.  It also of course pads the interior so your carton of eggs stands a better chance of making it home in the same number of pieces it started out in at the grocery store.

Without further ado:  Here’s a look at the end result:

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And here’s what it looked like before I took a knife to it:

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This is a “Therm-a-Rest RidgeRest Classic Foam Camping Sleeping Pad” in its Large size, which is 77″ long by 25″ wide.  The important measurement is the width:  25″.  Thats only 1″ wider than the measured 24″ width of the Rothco Parachute Bag we are using for this project.  In actual practice, stuffing it into the bag, the width is perfectly sized to the bag.

What about length?  Well, I found all you have to do is cut one of these sleeping pads in half, widthwise.  This will give you two 25″ wide by 38.5″ long pieces.  That 38.5″ is pretty much perfect insofar as lining three sides of the bag (rear, bottom and front face).

Having this sturdy but padded liner inside the bag, you can pile stuff on inside and the bag retains its squared off shape.  Further, when using the straps to lift up the bag off the lower rack, the liner allows those straps to carry some of the bag’s weight without flopping down onto the rack in its center.  Without the pad as a liner, none of that good stuff happens.

Here are a couple of shots of the bags, empty, and folded up.  Here again the pad on the inside gives these monstrous panniers shape so they can fold up and stay neat/tidy.

 

You can see from the pics above how useless those big straps would be without some sort of internal structure (also notice these are still the early 2″ straps).  That internal padding is crucial to making these bags work.  Now lets look at the bags loaded:

 

See that grocery cart in the background?  Well, it was mostly full and now its loaded up into the Mongoose.  Filling both the 25L (each) front panniers and these almost 77L bags in the rear.  Those bags are still well-loaded but as you can see by no means full.   They are loaded mostly with 2L juice bottles, a case of 500ml coca cola bottles and a slew of soup cans and such.  With all that weight, the straps can still hold the bags up and partially off the lower rack and retain their shape (although I did add a third 2″ strap in the center to supplement the two outer 3″ straps… this load was *heavy*).

So… thats why you need the pads.

Finally, what do these bags look like when truly, fully filled out?  Recently I took some old XL sleeping bags out of the house.  A city park was midway to the drop off point and I pulled over for a quick set of pics.

 

 

Heat Sinks For the BBSHD Ebike Mid-Drive

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

Whats The Problem?

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

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

AND

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

AND

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

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

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

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

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

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

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

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

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

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

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

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

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

Cheap DIY Cargo Bags: Update

Recently I posted up about how I made some Big And Cheap DIY Cargo Bike Bags.  Since I made that post, I have made a couple of improvements worth mentioning (including learning to lock my front wheel… look closely at that pic above… doh!).

The Straps

While I discussed them in my original post, my use of 3″ wide straps hadn’t actually happened at that time.  The straps were in transit.  They have since arrived and been installed.  I do prefer the wider size, and the shorter length of just under 60″ (I’m using two 30″ straps connected together).  You can see them in use in the picture above.

It is worth noting the clumsiness I experienced with the longer 2″ x 72″ straps went away with a couple of days’ use.  I simply got used to them, so as I mentioned in my original post, there is nothing wrong with 2″ straps.  1-piece, 2″ x 60″ straps should work just fine, will cost a bit less and be a hair less complicated.  Although they will give a little less support.

The Hooks

Discussing the improvement to the hooks is a bit more involved.

Lets backtrack a step: Originally when planning this project I ordered some AN970 Large Area Washers from Pegasus Auto Racing Supplies.  I intended to use them in conjunction with the M5 mid-frame braze-on bosses on the Mongoose Envoy to permanently anchor the bags to the side of the bike.  Later on as the project matured I decided to just use the straps and not bolt the bags to the bike.  So I never utilized these washers.

I bought the 1/4″ size which have an outside diameter of 1.125″ (28.6mm).  Inside diameter is suitable for an M6 bolt, and usable with an M5.  Washer thickness is 1.6mm so these are very beefy.  Additionally they are made with Grade 8 heat treated steel.  These washers are VERY strong.  I have used the 1/2″ size, unsupported except for a nut, to secure end link bushings on a track (race) car and they held firm without bending in that very extreme job.  If you toss your bike out of an airplane, these washers will probably be the only thing not bent on impact.

So… I have a bunch of unused washers.  So what?  Well, as you can see from the original build, the S hooks fit inside of a fairly large 13/16″ hole.  The hook has plenty of lip to hang on thru bumps and bonks while going down the road, but it still moves and there is a little rattling.  I hate rattling.  When I build a bike it doesn’t rattle.  I don’t care how big of a cliff you ride off of.  No rattles.  So… I took steps.  Afterwards, the bags remain easy to remove from the bike.  You just do it differently.

img_20191201_082723
Fig. 1:  Here’s everything we need to get the first part of the job done (stabilize the connection of the hook to the bag)

Step 1: Attach the big washer

These washers are big.  1 1/8″ wide in fact (essentially the same size as a headset stem cap).  They are so wide they cannot fit inside of the narrow end of the ‘S’ hook unless we spread it a bit.  So lets do that.

Take your pliers and spread the small end of the ‘S’ just barely enough so the washer will fit inside of it.  Fit the washer in and then again being very careful not to over-crimp the ‘S’, take it back to being the same shape (parallel) it was originally.

When you are done, you can stop here and fit the resulting product onto your bag grommet to see what you have accomplished.  You will fix the hook by putting the big end thru from the inside of the bag.  It will look like the picture below.  At this point the connection is much more solid and when on the bike very unlikely to come undone unless you want it to.

img_20191201_083417
Fig. 4:  If you over-crimp the hook it will be too tight and will no longer fit.  If you leave it spread out, it will rattle and move around.  Just put it back the way it was before you put the washer in and everything will be fine.

So, we could stop here, but if you recall, I said no rattling.  So lets take this another step to further solidify the hook into the hole and, as a bonus, make it silent.

Step 2: Add mastic tape to washer

Everyone knows duct tape is a gift from the Gods.  A million uses.  For bicycles and particularly ebikes, 3M Moisture Sealing Tape, Type 2228, is even more useful.  This stuff is available at your local hardware store for about $10 a roll for the 1″ wide stuff.  Its magic comes from the fact it is 65 mils thick (five or six times thicker than what you think tape thickness should be) and is a soft, adhesive rubber that can be stretched, bent, squished and molded as you see fit.  And when it sticks to itself it literally welds together.

For this job, for each hook I snipped three snips of tape, each about 5mm in length.  I didn’t actually measure – no need to be so precise.  I just eyeballed it.  Two of the snips went to the inside side of the washer, pushed inward to hold the hook in place and more or less fully face the washer with thick, soft rubber tape (3 guesses on how that affects rattling).

img_20191201_083921
Fig. 5:  Do a better job than I did here and cut yourself a little more tape so it goes edge to edge on the washer.

Step 3: Add tape to hook

With the above complete, plant the hook in the grommet hole – now you have to do it from the inside of the bag – and use the third snip to wrap around the hook, so the tape is between the hook and the grommet face.  Like so, below.  This will be a snug fit, but the tape’s tendency to weld to itself makes this job certain despite the fumblefingering that will ensue during job completion.  When done, you have this:

img_20191201_085540
Fig. 6: The 3rd strip of tape silences the hook rattling against the grommet.

Repeat the process with all four hooks.  Here’s a peek inside the bag.  Notice the washers completely cover the grommet hole.

img_20191201_090027
Fig. 7:  View from inside.  Pretty sturdy connection compared to poking a hole in fabric with a hook.

The hooks worked fine as conceived in the original build.  But these are now a  more secure, stable mount.  For long term use this is a better way to do the job, and the cost to do it is about 80 cents.

FYI its fine if you don’t use these Grade 8 uber steel washers… look for something similar at your hardware store, probably a 1/4″ zinc fender washer.  Cheaper, too.

Upgrade The Hooks

This is not such a big deal but it works just a little better.  All of the pics above use the black steel hooks that presently retail for $8.99.  These hooks are powder coated so the black is on there pretty good,  But its not going to be perfect, and rubbing paint (bike frame) on powder coat (hook) means you get some rubbing off on both the frame and the hook.  Plus that powder coat isn’t as smooth as polished steel.  These hooks come in a polished steel option for an additional $1 for the 30-hook pack.  I got a pack of these and they seem to fit more smoothly against my frame (where the hook is exactly the size of the frame rails, so fitment is always rubbing-tight).

There is a slight cosmetic difference as they are slightly visible now whereas the black ones were not.  I’ll leave it to you do decide if you care.

These hooks, in the best tradition of Chinese marketing, are described as “premium metal steel” so we’ll have to see whether either behaves differently.  I am using polished on one side and powder coated on the other.  Time will tell if either will rust.

I Hate Ebike Torque-Sensing (maybe you should too)

Well, I don’t actually hate it, but I have no love for a technology rooted in cycling’s past, and whose existence, in my opinion, is primarily owed not to the fact that torque-sensing is a better system, but instead as a tool to help persuade an existing customer base (recreational cyclists) not to hate the product (ebikes) quite as much as they already do.

Say what?

What is Torque-Sensing Pedal Assist?

On an ebike, when a torque sensor is used, it applies a strain gauge to the drivetrain (located either inside the bottom bracket, or in the back of the bike near the gear cluster).  This measures the amount of force you apply to your pedaling stroke.  If you pedal (work) harder, the assist you receive is dialed up.  If you pedal more softly – regardless of your cadence – the assist level is reduced or eliminated.

I have heard it said that torque-sensing “rewards pedal effort” and this statement is both correct and indicative of the root problem with its advocacy.  Old school cyclists hate Hate HATE the fact ebikes can allow someone to make forward progress without using their muscles in the first place.  By restricting/keying the assist to physical exertion levels, the fact that a motor exists at all is less difficult to accept – and more easily sold to the existing cyclist population.

It is unfair to say torque-sensing is ONLY about this.  Its not.  You will also hear people say torque-sensing results in the most ‘natural’ bicycle riding experience for them, since you still have to work hard on the pedals.  And the assist increases in proportion to your effort, just like a real bicycle.  An ebike goes faster of course, but a physical work ethic is still demanded.  So to be fair, torque-sensing does indeed give cyclists a familiar experience, and one that they may specifically want.  There is nothing wrong with that.

What is Cadence-Based Pedal Assist?

In its simplest form, its nothing more than this:  Your assist level goes up or down based on how fast the crankarms are turning.  The amount of effort you expend could even be irrelevant if your gearing is low enough.  The only thing that matters is the rotational speed of the pedals/crankarms (strictly speaking it is the spindle’s rotational speed that is measured, but thinking ‘pedal rotation’ is easier to visualize).

So if you want more assist, you just turn your legs faster – not harder.  Again in simple circumstances this means you can get into a low gear and easily ‘ghost pedal’ your ebike, without expending any effort.  So you are breezing right along right up to either the speed limit of the ebike or the road/path you are riding on. 

Such a thing is utterly anathema; deeply, personally hated in the cycling community.  There, your progress and ability is hard earned through what can only be described as prolonged, personal, stoic suffering whose level outsiders neither understand nor hope to match.  Despite the spandex, funny hats and silly shoes, cyclists know they are truly badasses.

Except, fate has dictated these solitary warriors suddenly have to share the road with the Griswolds, blowing past them in their two-wheel Trucksters.  Ebikes democratize cycling so that now… anyone can do it?  WTF!?!

… not a shock the response of cyclists to ebikes has been negative.

Its not so simple

I said above the description of cadence-based pedal assist was in “its simplest form”.  There are some cadence-sensing ebike motors that have settings both complex and rather profound in how they impact the riding experience.  Notice I did not say ‘cycling experience’ because a central tenet of my rejection of torque-sensing is that ebikes are not bicycles.  It is a mistake to treat them as if they should behave the same (unless that is something you expressly want).

img_20191102_131419
Some cadence assist options are at left, and this isn’t even the Pedal Assist screen for this particular motor.  The settings determine assist strength and at what point, based on both speed and rpms, that the assist gets cut back.  Other screens have settings to determine how much the cut-back is, how fast it kicks in and more.  Not at all the simple concept most internet experts describe as their idea of cadence assist.

Torque-Sensing Can Be A Disaster

If you have a physical limitation, torque-sensing doesn’t necessarily help you get past it.  It does help you go faster while working hard.  Studies have shown that ebikers in fact can work nearly as hard as, or even harder than bicycle riders… they just don’t realize it.  Possibly this is due in part to the exhilaration of being able to go faster, and stay in the saddle for longer periods.

Myself, I am a lifelong cyclist.  Or rather, I was.  I commuted daily for decades.  For many years I eschewed the use of an auto.  I commuted and even shopped for groceries by bike (being poor and single had nothing to do with this 🙂 ).  But after a couple of heart attacks, my cycling life was over.  To stay alive, I gave up the intensely personal activity I most valued.  Bummer.

A few years ago, I discovered ebikes, and the one I bought had cadence-based torque sensing.  I had no idea there was another kind of system at the time.  I did something many old-schoolers do not:  I treated the ebike – which looks like a bicycle but is not one –  as a new animal.  I threw out much of of the knowledge on cycling I had acquired, and started over on riding technique.

At the start, pedal effort very quickly led to chest pain and an immediate need to stop doing that.  But I could go on if I dialed up the assist and incrementally lowered my pedal effort, while maintaining forward progress.  This doesn’t work with torque sensing.

I learned to treat the ebike like an exercise machine.  An exercise machine that went places… and was practical transportation.  This approach to riding an ebike and incrementally notching the assist level up and down as needs of the moment dictated solved everything.  The procedure in a nutshell is as follows:

  1. Set a preferred cadence
  2. As heart pain occurs (heart pain /= being tired) click up the assist level so I get closer to or completely ghost pedal the bike – and keep moving
  3. On recovery – I’m good after maybe a half block – ramp down the assist level a click at a time and start working harder again
  4. All the while – maintain the same cadence
  5. Rinse and repeat as the miles click off.

Again, to belabor the point:  This is transportation.  My bike has somewhere to go, so the point of cycling is to reach a destination.  If I was a recreational cyclist then maybe its fine to stop and sit on a bench for awhile.  But the point of riding for me is to get somewhere.  So I must maintain forward progress while managing my exertion level.

Only cadence sensing is going to let you do that (and I know this from experience.  See Afterword below).  Its a totally different riding experience.  In the end, described most simply, you have an exercise machine that is moving.  Again… not a bicycle.

Over time and thru repetition, I scaled back the point where pain occurs to where I was able to change my bike’s gearing.  Now I’m running at top assist speed while maintaining pedal pressure and exertion at all times during the ride.  On my Class 3 daily driver I cruise right at 28-30 mph (legal in my jurisdiction) and I get to those higher speeds above the assist limit by myself.  All along doing so by maintaining a set, preferred cadence.

And if I overdo it, since I am now running this auto substitute at full power, I can just upshift (maintaining cadence on the easier gear) to take a break while only losing a mph or three.  This is a different way to use cadence-assist.  I am not dialing back power: I’m always running at full blast.  Instead I am just varying my pedal effort up and down via gear changes.

What happens to a rider with physical restrictions who tries to depend on a torque-sensing ebike for transport?   You ride, you need a break and an assist and… the bike tells you to fuck off.  Its not going to help unless you work hard enough to deserve a reward.  So much for dependable transportation.

Broadening The Use-Case

Cadence sensing isn’t just for recovering invalids.  For the healthy rider, successful use of cadence-based assist as a hard-exercise tool is easily possible, and rooted in that rider not coming into the experience with pre-conceived ideas.  Don’t treat it like a bicycle (yes I am repeating this over and over on purpose).

Using the ebike as an exercise machine as you roll down the road, you’ll be getting fit during time otherwise spent sitting in your car and exercising nothing.  A torque-sensing ebike can do this too… but if the ebike is meant to also be practical transportation, your physical condition of the moment will have a direct impact on whether you make it to your destination.  Not so with cadence assist.

The Future

It took 34 years for the Tour de France to allow bicycles with derailleurs — because not grinding up a slope in the Alps on a single-speed was cheating.

… Isn’t it better to triumph by the strength of your muscles than by the artifice of a derailleur? We are getting soft.

-Henri DesGrange, world-renowned cyclist and original TDF organizer

If someone tried to make that same case today, their opinion would be discarded as fringe idiocy.

So lets take that same interval: 34 years from now, when ebikes have long-since become the accepted norm (just look at the sales figures) as derailleurs did a century ago… will we be espousing technology or methods rooted to the norms of the past?  Will a couple of generations of riders who have known nothing else continue to think of torque-sensing assist as giving a bike a ‘normal’ feel?

My money is on ‘no’.  Or more accurately… sorta-kinda-no.  I think for higher end bikes a dual system could become commonplace, letting riders choose one or the other as they see fit in the moment.  One mode for recreation.  One for transportation.

But if it has to be a this-or-that binary choice, then torque-sensing won’t survive the test of time.  Why?  Sheer weight of numbers, and the growth of the automobile replacement market.  Look at global ebike sales.  Only a small fraction of ebikes are sold in the European and North American markets, where recreational cycling is a thing.  Instead look at the Far East, where bicycles are simply utilitarian transportation and there is no stigma attached to effortless travel.  Whats the norm there?

Cadence-based assist.

 

Afterword

Lest I give the wrong impression… I have an ebike that uses torque sensing, and frankly I love it.  But its a recreational bike, not suited for a bike that has a job.  Going for a fun ride, where I don’t have a problem stopping and sitting down on a bench or a rock for awhile and enjoying my surroundings… Its almost perfect for that.  I wish I had time to ride it more.

But by its nature it can’t be a serious transportation tool.

 

Big And Cheap: DIY Cargo Bike Bags

There is another post that shows later improvements to these bags.  Here is another one that covers a hole I left in this article below.
Great Big Bags 2.0 uses a better attachment method.

I have a Mongoose Envoy that I turned into a project bike.  I essentially took a very inexpensive bike with low end components (but a fantastic frame, with a good fork and wheels) and rebuilt it into a high power, heavy duty cargo bike with better components than I’d get if I paid for one from a major manufacturer.

The Envoy comes with two almost-38L-each panniers (24″ long x 16″ tall x 6″ deep).  Thats one hell of a lot for a bag on a normal bike.  But on a mid tail cargo bike frame, they’re smaller than what they could be.

The stock bags look skinny, and are no thicker than a normal pannier.  But I’ve had them loaded with a complete Costco grocery run where the bike ended up well past its 140-lb rated cargo capacity.  Using an elastic bungee net to make sure everything stayed tight to the bike, all I had to do was lumber home without killing myself.

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Figure 1.  A light shopping run – not using front bags.  The bags we’ll make here are about the same size as the ones shown, but more than double the width.  Note the cargo net used here as insurance that those bags stay put.

So… the bags work great and are essentially free.  But I’d like something that better suits the capacity that the mid-tail cargo frame can handle.

I managed to score a brand new set of Surly Dummy bags for a great price.  I found they were great bikepacking bags not suited to bulk grocery hauling.  Whats needed is a giant hole you can dump stuff into and zip closed.

It looked to me like the Yuba Go-Getter bag ($300 plus shipping for the pair) was the closest fit to this idea, and to my frame (It is meant to fit their popular Yuba Mundo cargo mid tail)  I contacted Yuba about the exact size of the bags, and that they would be going on a non-Yuba bike.  They promptly got back to me with this:

  • Length – 29″ / 74 cm
  • Depth – 10″ / 25cm
  • Height – 17″ / 43cm
  • Volume comes to about 84 quarts or 79.5 liters.
  • It is important to note that we designed the Go-Getter to be specifically compatible with our Yuba Mundos and we cannot guarantee its compatibility with non-Yuba bikes.
Go-Getter-Angle_600x600
Figure 2: A single Yuba Go-Getter bag mounted on a Yuba Mundo cargo bike.

Thats pretty awesome in terms of capacity.  However, those dimensions are just enough to worry me on my bike.  The Envoy’s bags are 24″ long.  29″ might end up pushing into my heel clearance.  The height of 17″ is for sure an issue.  Envoy bags are 16″ tall, and its already a problem that those bags essentially sit directly on the lower rack.  While the bike frame is rated for 90 lbs, the lower rack is only rated for 20 per side, or 40 lbs total.  Now, they can handle much more than that in real life, and I have reinforced the lower rack’s attachment to the frame (Supplementing the factory’s four connections with an additional six that are each stronger than the simple factory bolt), but still a bag that basically sits its weight on that lower rack is not ideal.

What would be better would be a bag that is a little shorter, that bows downward under load, putting strain primarily on its hanging hooks, so only partial weight is borne by the lower rack.  Add in a couple straps to help take the load off those 4 hooks and its better still.

I think my solution accomplishes that.  Bear in mind everything I did here was done specific to this bike.  You can take these ideas and make adjustments so this basic concept fits to yours.

The Budget

Lets call the number I am trying to beat the cost of the Yuba Go-Getter bags, which were my benchmark for capacity:  $300.  So I wanted this project to come in as far under this number as possible and still get a quality bag.  As you can see from the build sheet below, I came in well under the commercial product’s price point.

Build Sheet ($111.50, or $55.75 each)

Rothco Parachute Bag (2)             Amazon   45.98
3"x30"velcro cinch straps (8)        Amazon   21.54
C.S. Osborne #6 13/16" grommets (8)  Amazon   11.36
Stainless 0.3"/0.78" S hooks (8)     Amazon    2.67 
Therm-a-Rest Classic Foam Pad        Amazon   29.95

The Bags

I want something more durable than the fabled, dirt cheap Ikea bag.  But really those bags got dropped as candidates because the zippered version is so short at 11″ that it would be putting the load unnecessarily high.  Also its 28″ length is again just enough to worry me.  And how sturdy is it?  The zipper in particular?

I had a candidate already in my hands in the form of a Rothco Parachute Bag.  These are simple, cheap $23 bags made of reasonably thick canvas and strong, smooth zippers with a snapped storm flap.  Dimensions are 24″ long (identical to the Mongoose stock size), 15″ tall (1″ shorter than stock, so addresses my height/weight concerns) and 13″ deep.  Work out those measurements to cubic inches (4680) and convert to liters and you have a 76.7L pannier bag.

Since I already had one of these bags in my closet, I was able to toss in some full size pillows (it ate 3 of them and still wasn’t quite full) and sized it to the bike.  Looked like a perfect fit.  So I bought two more for testing.

Attachment

After a fair bit of fussing around, trying to figure out exactly how I wanted to attach the bags to the bike (it actually took a few weeks), I settled on primary support being grommet holes in the bags, which will connect to simple S hooks mounted to the frame.  These will be further supported by straps.

I used the C.S. Osborne #6 grommet, which has a 13/16″ hole.  Why this brand and size?  Well, there are drapery grommets, shower curtain grommets and outdoor tarp grommets.  The grommets for curtains are nowhere near strong enough to work on a tarp… or a pannier.  I knew from experience the Osborne grommets are solid and will distribute the forces involved as well as possible.

I chose a 13/16″ size because… I had the grommets and the grommet tool already.

20170218_143537Sidebar:  The #6 grommet size is the smallest size commonly available that will let you fit an XT90 connector thru the hole.  Thats why I have the grommets and tools in my garage – from building battery bags for my custom ebikes.  I grommet the pass-thru holes in the bags.  And since I have been using them for years, I know they hold up.  The bag on the right was made in early 2017 and is still in use today.  This $12 Amazon bag with reinforced holes is way cheaper than a custom ebike bag.

  • You can see in the first pic below, three of the four grommets’ upper edges match the seam of the bag, while the forward-most grommet is lower.  Oops.  My second bag had them all even and all in the lower orientation.  Despite the different mounting, you can’t tell the difference in how they sit on the bike.
  • The single brass grommet was deliberate as I wanted a quick visual cue to help me orient the bag.  Brass = rear for both bags.

Straps

Not wanting to rely totally on the hooks, there are two dedicated three-inch velcro cinch straps.  These are actually made up of two 30-inch straps combined to make one longer strap.  I had to do this as there does not appear to be a 3″ wide velcro cinch strap in a 60″+ size on the market.  If you wanted to save some money and use a narrower strap, 2″ cinch straps are widely available.  In fact, the pics below show an early test fitment where I was using 2″ x 72″ straps, which worked OK but were so long they were a bit unwieldy.  Shorter straps were more convenient and the wider 3″ version provided more support.

The right way to use the straps:  Loop over the rack at top, and the very bottom, directly underneath.  But do NOT loop under the lower rack and then go up over the bag.  Instead, from the bottom of the bike frame, loop the strap directly under the bag and then back up to the top.  The top loop over the rack helps support the bag’s weight.  The bottom loop onto the lower portion of the frame (or rack depending on your bike) helps hold the bag close to the frame so it won’t flop around.  And the remainder of the strap, directly up against the bag and not under the lower rack, holds up the bottom of the bag, preventing – along with the padding – the bag from sagging.

Hooks

These are pretty straightforward.  I wanted an S hook with beveled edges that allows quick attach/detach, but at the same time is shaped in such a way that the bag will not easily come undone from it as I bounce from pothole to pothole.  I searched for months for such a hook for a cargo net and fell into the ones I am specifying in the build sheet.  Originally meant for my cargo net, they are also perfect for this project as well.  I have the painted black versions but I am spec’ing the unpainted stainless versions.  For your own personal bike, you may need something different.  Follow the link above and note the seller offers three sizes.

More Options

  • Most of the reason I used pre-made cinch straps rather than buying webbing and fastex-style buckles is that hook/loop strapping is much easier to adjust.  This makes it easy to cinch up the straps when the bags are empty, and fold the bags up quite nicely.  There is even a deep, wide pocket formed by this process that is a decent candidate for stuffing in whatever fits.
  • During testing of the bag when fully loaded, I ran a 15″ x 30″ cargo net from my top rack, over the bag and underneath to the bottom rack.  It provided great support to keep the bag from sagging, and held it firmly, close to the frame.  For really heavy loads this looks like a smart thing to have available; especially since it can lay flat in the bottom of the bag and take up no extra space.
  • I have a 24″ x 36″ cargo net (see it in action in Figure 1 above) that I can use to stretch over my entire cargo area.  Up over a side bag, the loaded upper deck and back down over the other side.  For big, heavy loads, a net like this can put a gentle, compressing and enveloping grip over the entire load in the rear.

Where Do You Go From Here?

Unless you have a Mongoose Envoy then your bags will need to be tailored to whatever your bike fittings are.  Expect to put the grommets in different places.  Maybe use a different size of S hook.  Don’t expect my project to work perfectly for your bike although the parts I am using should be mighty close to universal once you space things out per your bike’s needs.

In the photo above: I had so much room in the new bags after loading up my shopping cart, I never even used the 36″ x 12″ duffel that sits atop my 40″ rear deck.  There is almost 154 liters of pannier space in those bags, and after dumping that whole shopping cart into them (the front bags helped too)… they still aren’t full!

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 so cashwise I am not out the full parts total).  Given how expensive quality cargo bikes are, and the level of quality I have now, I am very happy with that cost vs. benefit.  I have a really solid frame and top quality components, and a bike that is probably the best all-around transportation/auto replacement bike I have ever owned.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Yikes we’re still under 2 grand here!

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Wrapping it all up…

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

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

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

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

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

So have at it!

How I Bleed My (Magura) Ebike Brakes

This is sort of a companion post/supplement to my Mongoose Big Brake post (go there for links to resources on cable cutting and bleeding).  Worth putting up separately as its a topic that comes up from time to time in my travels, and putting it here will let me just link it into a discussion.

These directions assume you are working with Magura brakes.  However, they should translate reasonably well for a generic application (for best results find specific instructions for your model).

Next time I do it, I’ll take some pics so I can spruce up the page a bit.

  1. Toss a small towel on the ground under the caliper you are bleeding.  Just in case Something Bad happens.
  2. Leave the caliper on the bike.
  3. Get everything ready because once this process starts oil is going to be dripping out of and onto things.  ‘get ready’ means in part to get your lower syringe with the bleeder hose fully filled in advance, with the hose filled with fluid not air bubbles.
  4. Loosen the lever on the handlebars and re-orient it so the brake reservoir is level to the ground
  5. Remove/open the top bleeder.  Since the bottom bleeder on the caliper is closed, nothing is going to be leaking out yet.  Attach the top syringe/reservoir.
  6. Open the bottom bleeder and haul ass to get the syringe screwed onto it.  I usually manage to get only a small dribble onto the caliper.  Tighten the syringe onto the bleeder with an 8mm wrench and make sure it is on tight (not ‘crank arm’ tight…  go just a skootch past ‘snug’).
  7. Do one cycle of bleeding, bottom to top and back to bottom, gently, to establish vacuum and  ensure you have a good setup and don’t have any leaks or surprises.  While doing this, periodically tap the caliper and fluid reservoir in the lever with something firm like a *small* dead blow hammer (or the handles of your pliers) to help dislodge any stuck bubbles.
  8. With a full bottom syringe, push the fluid up through the system… hard this time.  Not enough to break the syringe or do something crazy, but enough so you can see the oil well up in a wave in the top syringe.  On the return stroke back down, be gentle so you don’t suck any air in via the edges of the top syringe seal.
  9. Repeat Step 8 until you no longer see tiny occasional streams of bubbles.  You can stop when fluid is in the bottom syringe, drained from the top syringe, with just a bit of fluid in the top syringe (say… 2-3mm or so) for the next step.
  10. Using the 8mm wrench, break the lower syringe loose and as soon as you are able, spin the thing off the bleeder by hand.  Have the bleeder screw ready to pop back on asap because fluid will start dripping out immediately.  Important:  The little bit of fluid you left in the top syringe will keep the reservoir topped up unless you screw up and are too slow to get the bleeder bolt back on..
  11. Remove the top syringe and replace the cap screw, taking care not to overtighten … its a plastic bolt and need to ONLY be snug (0.5nM, officially).
  12. Mop up.  Chances are good you only got a little on the caliper from Step 9.

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 5 (Motor Install)

There are about a billion step by step Youtube videos and forum posts describing the steps that go into installing a BBSHD onto an existing donor bicycle.  They already do a great job so I won’t try to get too deep into the weeds on that.  I will say that installation on the Envoy was simpler than my previous builds on different bikes, which is only a good thing for you if you aren’t familiar with installing a BBSHD onto a bike.

Step 1: Prepare the bicycle

You are going to be pulling apart some things and replacing them, so you’ve got some prep work to do.  Myself personally, I decided to do the following which you should consider optional.

9 Speed Conversion

I converted the bike to a 9-speed from its factory 8-speed.  You already have to say goodbye to the stock shifters Mongoose gives you with the bike since they are integral with the brake levers, which themselves have to go.  So I decided to bump up my options a tad.  8, 9 and 10-speed systems will fit interchangeably on the same hub.  I also have other bikes that are 9-speed and I like to have common parts between them.  Plus, I already had a cluster in my parts pile that was 9-speed :-).  So 9-speed it is.

As noted in the Motor Choice chapter, if you decide to stay 8-speed, you still need to replace your cluster as part of your mid drive upgrade.  A Shimano CS-HG31 8-speed cassette in 11-34T is about US$17.50.  You can bump that up to an HG-50 with nickel-plated steel cogs (not a bad idea) for about US$22.  At that point you will need to buy yourself some 8-speed shifters since, as noted above, the stockers can’t stay.  You’ll be able to keep the derailleur that comes with the bike (which frankly is not something that appealed to me… the one on my bike worked poorly and was clearly a basic, commodity component).

So here was my prep given this 9-speed conversion:

  1. Remove the handlebar grips without destroying them.  I used a jeweler’s screwdriver to lift up the edge of the grip, which let me get a WD40 straw nozzle in there and give it a spritz.  A couple of those and I was able to work the grip loose without having to cut it off.
  2. Release the brake cables.  This entails releasing the cable from the brake caliper so the lever flops free.  Then you can easily remove the cable from the lever.
  3. Release the shifter cables.  Release the cable from the derailleur and then pull the cable out of the housing so it is free.
  4. Remove the shifter/brake lever from the handlebars.  Just loosen the screw and slide them off.
  5. Remove the chain.  The Mongoose chain does not have a master link, so you will need to use a chainbreaker.  This chain will not be re-used.
  6. Remove the front derailleur from the bicycle.  Not used on a mid drive, so it goes into the bin.
  7. Remove the front derailleur cable housing.  Since the cable is routed thru the frame, this will give you an unused entry and exit hole in your frame which you’ll want to seal up with something.  I used a bit of rolled up mastic tape.
  8. Remove the rear wheel and replace the rear cluster.  You’ll need a chain whip and a cassette removal tool for this.
  9. Remove and replace the rear derailleur (optional.  See above.)
  10. Remove both pedals from the crankarms (or better yet don’t install them in the first place when you take the bike out of the box).
  11. Remove the crankarms.  You will need a proper sized socket to get the bolt out, then a crank puller tool plus a big wrench to finish the job.  Repeat for the other side.
  12. Remove the bottom bracket.  You’ll need a standard bottom bracket tool such as a Park BBT-32, and again a big wrench to turn it.

Prep work complete.  The bike now looks like the picture below, minus the big cargo net.  You’re ready to install the motor now.

IMG_20190928_102436
Fig. 2:  At this point your bike will look about like this:  No pedals, nothing on the bars and loose wires hanging around.

Step 2: Attach The Motor

It will fit right into the empty hole that used to house your bottom bracket.  At this point the motor is hanging straight down in the bottom bracket thanks to gravity.  You will want to dig into your installation kit’s parts bag and retrieve the two M6 bolts and the fixing plate that will clamp your motor to the bottom bracket.

One side of the fixing plate is ridged. These ridges are there to bite into the bottom bracket.  they go a long way (most of the way) towards holding the motor up and in place.  Before you slide that plate onto the motor’s axle, you need some spacers between it and the motor to support the plate, but not so many that you get in the way of the plate clamping to the bottom bracket.  Usually I use fixed-size steel spacers that I get from McMaster-Carr (you can buy them in various lengths in 1mm increments), but in this case I just used three M6 washers and got a perfect fit.

IMG_20191008_174717
Fig. 2a: The fixing plate, with those all-important ridges that must directly contact your bottom bracket.  In background: a couple of outer trim rings, and the  M6 bolts you’ll use to attach that plate to the motor.

Using just this plate clamped gently to the bottom bracket, its possible to get a provisional fit on the motor without fully tightening it.  Here’s where, essentially, the only hiccup in the installation occurs:  The rear shifter cable exits the frame just ahead of the bottom bracket, and travels under it.  If you rotate the motor up as high as it can go – which is the most desirable position – it will pinch the cable and seize it up.  So you have to back off a bit.  The picture below shows what my cable looks like after a successful positioning of the motor that allows the cable to move freely.

mongoose01.jpg
Fig. 3:  The arrows point to the shifter cable exit point and the allowable bend.  Also visible is a wad of mastic tape I used as a makeshift bumper to help solidify the motor’s position during installation

To ensure you’ve got the motor positioned right, use your replacement shifter cable and just manually run it down into the housing.  If you can get it thru easily so it pops out the other end, you are good to go.  Once you get the motor positioned up so that it a) gives max ground clearance and b) does not interfere with shifting, its time to tighten it down fully.  You will use two clamping lock rings over the axle and bottom bracket.

Typically, you use a grey, thick inner lock ring to do the real work, and the thin polished black outer lock ring – which is essentially just there to look good and perform sort of like a jam nut.

IMG_20191008_174043.jpg
Fig. 4: Note the thick black Sharpie registration marks running along the top of the two outer rings and the bottom bracket.  If I ever look down and see those marks not lining up, something is slipping and needs attention from a torque wrench.

However, using an inner and outer ring requires two tools.  The inner lockring is physically covered by the outer lock ring, so you can’t see it, but if you look in your parts bag the differences are clear.  Pictured above is the same installation done with two inner lock rings stacked on top of one another.

The outer ring is essentially a trim ring.  Its there to look nice and serve light duty as a jam nut.  Using two inner rings means you can torque the bejesus out of each of them.  And speaking of torque, I use a 1/2″ torque wrench to put 100 ft lbs of torque on each of these two rings.  Yes, 100 each is well above the ‘official’ spec but it is proven to work.

A note on tools:  Cheapie Bafang wrenches made of thin steel will let you ‘get by’ with a basic tightening of these lock rings. They are widely available for roughly US$15.  I don’t recommend their use given the lack of ability to use a torque specification, and their small size.  Pass on these and your knuckles and palms will thank me, as will you when your motor does NOT loosen since you used proper tools.  To do the job right, you need to use something like the socket found here.  You want the ‘inner’ socket only unless you want to use the trim ring instead of the two inners.  Worth noting: This socket is also sold at Luna Cycle (they also make their own version that is intermittently in stock) and California Ebike.  Pair this up with the torque wrench of your choice.  Mine is this bad boy.

Step 3: the Chainring

The stock BBSHD chainring is solid steel and, well… its awful.  Not only is it the ugliest chain ring in the solar system, its design is known to drop chains and generally make owners’ lives miserable.  And it also weighs a ton.

IMG_20191008_174708
Fig. 5: the Disc of Death.  A medieval throwing weapon that coincidentally is also used as a Bafang BBSHD chainring.

You want to use one of the aftermarket alternatives out there.  Generally I buy Lekkie Bling Rings, where the 42T size (there are many available) with its 18.3mm offset is the size of choice (there are now Chinese clones of the Lekkie and they are so expensive its not worth taking the quality risk to save so few dollars) and works great to correct the chain line offset that comes from the BBSHD’s secondary housing sticking out as it does on the drive side.

However, for the Mongoose project I finally had a bike whose frame would allow me to use the other king of the BBSHD chainrings:  The Luna Eclipse.

As you can see in the gallery above, the Luna Eclipse ring has a serious inward offset.

24.8mm in fact, which brings it in more than 6mm close to the frame than the Lekkie can.  Add to this the unique, wicked narrow-wide tooth profile on the Luna that effectively means you will never, ever suffer a dropped chain.  Lastly, needless to say, it looks gorgeous.  But, the biggest deal is the enormous offset, which allows perfectly centered chainline… not easy to accomplish on a BBSHD build.

Step 4: Size and attach the Chain

I made this part difficult to illustrate because I put the bags on – so they don’t come off – before I took pictures of the chain and derailleur.  I’ll do my best to get through this without good pictures.

First and foremost, let me say that a great many builders get chain length completely wrong.  Unfortunately, a lot of them may have gotten their examples from bike manufacturers who skimped on chain length and did ‘good enough’ instead of ‘best’ to save a few bucks.  What do they get wrong?  They let the derailleur cage stretch forward; not understanding that it is the cage’s job to wrap excess chain… so let it do its job!  The only reason to stretch the cage is to use less chain (i.e. you are a bike manufacturer out to save a nickel or so).  By the way, stretching the cage also extends its springs, and which lasts longer… a device whose springs are at rest, or that are under stress?

Here’s just about the only published source I’ve seen that boils down how to do it right, although they don’t shout out to the high heavens what they are doing right that so many others get wrong.

I’ll lay out the process very briefly here:

  1. Shift down into your highest gear (your smallest cog, the furthest outboard from the frame)
  2. Run your new chain thru the drivetrain, so its unattached ends are on the underside of its loop, halfway between the front chainring and the rear axle (this is simply the easiest location to work with).
  3. Pull the unattached chain ends together so the rear derailleur cage is only slightly tensioned.  That means in the case of the Mongoose, where we have a long cage derailleur added into the mix, that the cage is pointed straight back behind the bicycle.  Believe it or not, thats how its supposed to work on the low gear.  The cage is wrapping as much chain as it can while still maintaining tension on the chain.  Here are low and hi gear shots taken at two different chain lengths on a different bike.  On the top-left-pictured setup, I was a little too generous.  But only by two links.
  4. Assemble your chain with your master link.

Forget about all the other tricks associated with determining chain length.  If you have a single front chainring, this is all you need to do.  Ensure there is sufficient tension on the little cog in back.  At this point you have added as much chain as you possibly can, so the big cog will take care of itself.  If you find you cannot wrap enough chain to make your big rear cog work, then that usually means you need to step up from a short cage to a mid-length, or from a mid- to a long cage.  Or just live with what you have because you physically can’t add any more chain.

Step 5: Cable Hookups

Sidebar: Why I used a triangle bag.
For this build, I chose to use a battery that is NOT hard surface mounted on the down tube of the bike (for now I am using the very safe, waterproof, crashproof LunaCycle Wolf Pack but I am not using its excellent magnetic mount).

I have decided to use a triangle pack simply because it hides a multitude of sins.  In particular it saves me the trouble of routing cables neatly and tidily across the frame, which in the case of the Envoy is made more difficult to do cleanly since there are no cable guides to piggyback onto, thanks to its internal cable routing.  The use of a dedicated ebike frame bag means I can just run my wires thru one hole and out the other without worrying about what they look like inside the bag.

A triangle bag also helps me with my goal of easy portability:  Long term I have a very specific small battery in mind that will sit inside of a cloth MOLLE pouch.  it will be a snug fit inside the triangle bag (thus no need for a hard mount), and when I am going into the store, I just unzip the triangle, grab the pouch, haul the battery out and set it in my shopping cart.  That internal pouch means my fellow shoppers are not looking at a bare high voltage battery with red wires sticking out one end.

Getting a triangle bag to fit your frame is often a challenge.  Getting one with ebike wiring cutouts doesn’t make things any easier.  Especially since the Envoy’s triangle is relatively large.  larger than pretty much all mass produced battery bags.  Except one.  The FalconEV triangle bag is one of the largest bags of its type and just happens to be a nearly perfect fit for this frame.  I’m using that bag here.

Hook up the Speed Sensor

I was pleasantly surprised to find I did not need to use an extension on the Envoy’s mid-tail frame.  However it was a close call.  The speed sensor must pass within 1/4″ of the magnet to be reliable.  To accomplish this I used a trick I have used with fat bikes.  I first wrapped the chainstay in a bit of silicone tape to make it grippy.  Then I used more silicone tape to affix a small rope/cable crimp sleeve onto my chosen spot on the chainstay.  The rounded exterior of the sleeve will mimic the chainstay when I stick the speed sensor to it, and finally a couple of zip ties in the prescribed loops on the sensor lock that little sucker down so it works perfectly and is going nowhere.

Connect the Battery Adapter

The motor comes with the ubiquitous red and black wire for its power feed, terminated by a pair of quasi-standard 40 amp Anderson powerpole connectors.  Actually, the Andersons are kind of dated, with an XT90 (and particularly the anti-spark XT90S) being a much more common, reusable and weather resistant connection to your 48v or 52v battery.  My kit from Luna Cycle came with another length of red/black wire, also terminated with a pair of Andersons on just one side and bare wires on the other.  The point of this ‘pigtail’ is to connect to whatever your battery wants as a connector.  Most likely that battery is going to have either another pair of Andersons attached to it, or a (hopefully female, for your sake) XT90S.  You use the Anderson pigtail to connect to another pigtail that uses whatever your battery wants.  Yes, this means you either need to a) solder or b) crimp together the two to make a proper connection.  If you have no skills in this regard, you can probably find a pre-made cable somewhere for an exorbitant sum.  Make sure it uses 8 or 10-gauge (thick!) wire.

(I Didn’t) Install the Gear Sensor

One way to trash your bike with a mid drive motor is to go hammer down on the throttle and then try to shift.  The bike will shift alright, with about 1000w of power behind it.  The sound that makes will tell you what a horrible thing you just did, and if you want to walk home some day with your snapped chain lying somewhere behind you on the ground, go right ahead and keep doing that.

There are many ways to keep this from happening.  Most of them old-school techniques developed before gear sensors came into common use.  Since I started riding before that time, and I already know you Don’t Do That by instinct, a gear sensor is optional for me.  Also since I am lazy I didn’t feel like wiring it in.  For others – especially for those new to mid drives, its probably best to use the sensor.

Here’s what you do:

  1. Attach the gear sensor to the motor – its the yellow cable end.  I am assuming you have one of the more modern BBSHDs and you don’t have to mess around with any sort of Y connector.  So we’ll pretend that problem doesn’t exist.
  2. Once the sensor is attached you now know where it can go on your frame.  See where it will line up best with your rear shifter cable, because you are going to fit it inline into/onto the cable.  So… pick your spot.
  3. Disconnect your shifter cable from your derailleur and pull the shifter cable out of the housing.  If you were following my prep steps above, you have already done this as I didn’t include a ‘replace the cable’ step there for this reason.
  4. With the shifter cable out of the housing, cut the housing at the place where you intend to install the gear sensor.  Place a shifter cable ferrule over each cut end of the now-separated cable.
  5. Run the shifter cable down the housing until it exits the cable where you cut it.  Push it out some more and then work it into the gear sensor, and out thru the other side.  Once you have it thru the sensor, run it in to the back portion of the separated cable housing and all the way back down to the derailleur.
  6. Cinch everything up so the sensor and the cable housing are all nice and snug against one another, and the now-inline sensor is placed as unobtrusively as possible.
  7. Reattach the derailleur cable.  Job done.
  8. Optional:  the gear sensor is nothing more than a little wheel inside of a box.  It senses when the cable is moving – when your shifter and derailleur are pulling on it.  As soon as the little wheel detects motion, it kills the motor and its torque for a split second.  That lets you can shift – even under full throttle – safely.  So… that little wheel can get crusted up with grit, and fail.  Early designs were infamous for this.  Modern ones seem to be free of the problem but be sure… spiral wrap that rascal in some silicone tape.  That seals out any possible crud ingestion so it will work forever without maintenance.

So, without the sensor here’s what I do instead:  While pedaling I …

  1. Stop pedaling and while not moving my feet
  2. Click my shift (always just one gear)
  3. Perform a single pedal rotation to make the shift happen (this is not enough to engage the motor with any worrisome level of torque) and stop pedaling.  the motor will engage and spin a little further, completing the shift as part of its brief power up/power down.
  4. Resume normal pedaling

That sounds like a lot but it takes about 2 seconds total.  Other folks have perfected the use of a brake lever as a clutch.  With some experience in the saddle, they can gently touch the brake lever just enough to activate the safety cutoff without also engaging the brakes.  Then they shift and release the lever.

Sidebar:  Magura MT5e ebike brakes have special levers that include a second hinge, mid-lever, that facilitates this brake-lever-touch cutoff method.

Wiring Harness Cable

A nice thing about the BBSHD is it has a single bundled cable that is meant to run up from the motor to the front of the bike, under the handlebars, where it splits off to connect up to the throttle, display and both brake safety cutoffs.  As clean as you can get given the multiple connections.  Just plug the harness cable into the motor, run it up and into the top rear of the bag, and out the hole in the front side.  The remaining dangly bits will connect right up to what you stick on the handlebars shortly.

On the Handlebars:  Display, Brake Levers and Throttle

These are pretty straightforward.  Place them where convenient for you, connect the color-coded plugs and job done.

Go Ride

Thats it!  You’re done.  I can guarantee you this:  It takes more time to write this article than it does to install the motor.  I think all in I needed only a couple of hours for the motor part, not counting all the extra work I made for myself swapping out everything else on the bike.