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
You are running the motor on a 52v battery, in its max 30 amp configuration
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.
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 cushy front air fork – was seeing motor casing temps of 165 degrees. Yikes.
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):
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.
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.
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.
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!).
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.
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.
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.
Fig. 2: Original is on the left. You don’t need to do much for the washer to fit.
Fig. 3: This washer has been fitted. The ‘S’ has not yet been carefully crimped back to being parallel in its original position.
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.
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).
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:
Repeat the process with all four hooks. Here’s a peek inside the bag. Notice the washers completely cover the grommet hole.
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.
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.
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).
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:
Set a preferred cadence
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
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
All the while – maintain the same cadence
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.
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?
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.
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.
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.
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.
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.
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.
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.
Sidebar: 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.
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.
Bottom loop over the frame. On the drive side you will want to be careful to ensure you are not contacting the chain.
Notice… the strap goes over the rack, not under it.
A lot of the weight of the bag is transferred to these straps.
3″ straps ended up being used in the final build to provide more support.
An early fitting using 2″ straps and testing use of a top strap to keep the two weight bearing straps together (turns out its not needed). Bag is stuffed with a king sized 0-degree canvas double sleeping bag… and its still not truly full.
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.
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!
So in Chapter 8, I put up a Build Sheet. If you do all the math, you will find my $750 bike turned into a $3600 bike (some bits, like the battery, I already owned and just plugged in). Given how expensive quality cargo bikes are, and the level of quality I have now, I am very happy with that cost vs. benefit. I have a really solid frame and top quality components, and a bike that is probably the best all-around transportation/auto replacement bike I have ever owned.
But what of all of this was actually necessary? I build bikes as projects. Generally, I am more concerned with making the bike the best it can be. I don’t pay as much attention to final cost as most people would. Especially since I oftentimes upgrade in bits and pieces, which is less of a shock to the budget.
Based on my experience with the stock Mongoose bike – seeing first hand what worked, what didn’t and what I changed because I had more money than brains – I can see a different way to go that might be of a lot more interest to people who just want a good bike that doesn’t break the bank. For the record, I’m of the opinion that the Mongoose Envoy represents a significant break from current cargo bike offerings in that it can be built into a first class solution for a lot less, thanks to its bargain basement starting price.
So… lets build a few different configurations using my kitchen-sink, spaghetti-against-the-wall build. In the end, I replaced everything but the frame, headset and fork.
All prices are in US Dollars, and I am assuming it is a given that this bike will be 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.
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.
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.
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 ($1,102.96)
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 they 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.
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.
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…
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.
Toss a small towel on the ground under the caliper you are bleeding. Just in case Something Bad happens.
Leave the caliper on the bike.
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.
Loosen the lever on the handlebars and re-orient it so the brake reservoir is level to the ground
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.
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’).
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.
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.
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.
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..
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).
Mop up. Chances are good you only got a little on the caliper from Step 9.
This section holds various bits that I changed that do not fit anywhere else or do not merit their own Chapter.
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.
Axiom Streamliner DLX rack
Axelrodz QR skewer replacements
5/32″ stainless steel fender washers
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.
Thudbuster Long Travel XL (450mm total length) in size 27.2
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:
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.
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.
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.
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.
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.
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″.
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
Stupid 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
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.
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.
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.
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.