Larry Vs. Harry Bullitt – Project Odds & Ends

The Bullitt Build
1. Battery and Battery Box
2. Cargo Box
3. Brakes
4. Front Motor & Wheel
5. Rear Motor & Drivetrain
6. Bits & Pieces (You are Here)

Whats Left?

I’ve hit all the big ticket items. Now for the bits and pieces that may be of interest.

Fahrer Panel Bags and Tools

The Fahrer bags were a late addition. Partly because they cost so damn much. I was not willing to spend the money until I finally realized my idea for a MOLLE panel, trimmed to size, with bags attached was just more effort than I felt like going to get the same result in DIY fashion.

For me, the point of these bags was to move my tools out of the cargo area. I seldom need to mess with/rummage through them so I wanted them in a place that kept them out of the way. At the same time, there is a fair bit of money wrapped up in this toolkit, not the least of which are the battery powered air pump and the ridiculously expensive but wildly useful Knipex pliers/wrench. For a bike that gets left outside of a store a lot, I wanted to be able to easily, routinely remove these bags for carry inside with me.

I settled on putting the tools in a bag that fits inside of the bag. Specifically I used one green and one brown Condor Field Pouch, which have handy top-grab handles for pulling the bags easily and quickly up and out.

Two of these bags, in two contrasting colors – green and brown – so I know which is which on sight.

Ordinarily these Condor bags are used for something like a 1L water bottle, but they are a near-perfect shape for form-fitting directly inside the Fahrer bag. The different colors help me remember straightaway whats in each pouch.

The contents of my tool kit fit along my usual lines: I want to be able to use what I am carrying to do just about any typical field repair. I like to work with full-sized tools, so I am not at a disadvantage on the side of the road where life sucks bad enough already if I’m broken down.

Worth mentioning are those two black disks in the pictures above. Those are not emergency field rations (unless its REALLY an emergency). Those are two regulation hockey pucks. Solid, dense rubber blocks. What the hell for? Set one each under the Bullitt’s 2-leg kickstand. Now either the bike’s front or back wheel is up and off the ground by several inches, depending on which way you tilt the bike. Instant quickee service stand.

Rear Rack

I’ve heard its tough to fit a rear rack on the back of a Bullitt. There are M5 bosses built into the dropouts, but it can be a challenge to utilize them as the brakes get in the way on the drive side.

I found an Axiom Streamliner 29er DLX rack fits perfectly.

UPDATE: Mar 22 2022. I actually used this slightly different Axiom rack that was sold as the Streamliner DLX. Nowadays this same rack is marketed as a 29er rack and now includes the extra-strong center mount (I used a spare from one of my Fatliners) as well as the stay mounts. The current Streamliner is narrower and sold strictly as being compatible with 700C tires (although I have one of them on the front of my Envoy that fits 26×2.8″ tires just fine).

Its lower mounting arms move the rack 4cm out and further back to ensure there will never be any heel clearance issues. Its strong – rated to a whopping 50 kg, although I don’t know about that. I’d say 25 kg is still pushing it, but as racks go its very strong and can stand up to any reasonable level of use. I use it to hold the more delicate items that come from the store. Bread, chips and such. Or if I am just expecting a large or heavy load I may attach the panniers so I can clean out my cargo bay so its one big empty box.

But the rack needs just a bit of surgery to fit. Note in the picture below I did just a bit of filing to give clearance for the brake adapter bolt. Without this small adjustment it won’t clear.

A bit of hand filing with a fine half-round file took just enough off of the mounting arm so it fits – without compromising carry capacity.

I also used the center mount from an Axiom Fatliner rack (I have several of them). It has about – literally – four or five times the material in it as the Streamliner center support. I did have to drill new engagement holes for it. Maybe I can get away with that 50 kg rating after all.

Kicktail / Reinforcement / reflector

I have done a reflector/kicktail before on many bikes as sort of a signature mod. I usually take a 6″ x 18″ street sign, stand on it, grab an edge and bend up until I have a lazy L shape of roughly 35-40 degrees. I drill some attachment holes and the result is a 1-piece rear rack deck plate. The kicktail ensures no mud comes up at the rider, ever. Coupled to other measures I like this approach better than a traditional fender.

To add utility, I also cover the underside of this kicktail in 3M 3432 Red Micro Prismatic Reflective Tape… Exactly the stuff used in manufacturing municipal street signs in the USA. It so happens that a few years ago I scored a 12″ wide roll of this stuff at a small fraction of its regular retail price, so I can just unroll a bit of it and slap it onto the back side of the kicktail and voila… the world’s largest red bike reflector. I guarantee you I am visible to an overtaking automobile even if I didn’t have my steady and blinkie taillights fired up.

But my usual racks are fat bike racks where a 6″ deck plate works in conjunction with mounting panniers. Not so with the much more narrow ‘normal sized’ tires of the Bullitt. I needed just a narrow strip on the top of the rack with channels on each side to allow the pannier hooks to be engaged.

So I used a narrow 2″ strip of aluminum flat bar in the full length that I needed, and then bent that bar up to the desired angle. Following that, I bolted a second, full-rack-width 4″ x 12″ piece of aluminum flat bar onto the strip to make the kicktail. Line the back side with tape and functionally the job is done. However, since I had discovered a green duct tape that is a near perfect color match for the Larry vs. Harry ‘Lizzard King’ green, I wrapped the upper surfaces of the rack with it for what I think is a nice look.

The ‘Bobtail’

So… the 2-piece kicktail… in the end I decided it wasn’t working for me. The giant red reflector was a big winner as they have always been, but the need to do a 2-piece thanks to the narrower rack caused issues that just grated on my OCD (just kidding I am not diagnosed with this condition). Being 2-piece, it jiggled around some while riding simply because it was heavier than its predecessors. Also, the metal plate rested directly on the rack and rubbed, scraping off the protective powder coating. Trying to pad that with 3M 2228 mastic was only marginally effective as the stuff inevitably wore down and mooshed away under the force of the metal edge bearing down upon it.

To solve this issue I re-thought my approach. I discarded the wide flat plate. Next I cut down the rack deck plate so it was just long enough to intercept all spray coming up off the tire. Then I lined the now-exposed rear with the same prismatic red reflective street sign tape used on the full kicktail. In the front, I affixed a swatch of orange prismatic tape to provide another reflective surface. To finish it off, after filing down the upswept end so there are no sharp edges, I took the added precaution of making a bumper with a layer of that same rubber 3M mastic.

Job done.

With this change, I hit the sweet spot. The bobtail still keeps water off of the rider, it still has a large reflective surface and I quickly grew to appreciate the shorter profile. Godzilla is already about 8 feet long before that tail comes into play, and I don’t miss bumping into the kicktail as I walk around the bike.

Rear Thru Axle

Surprisingly, sourcing a proper rear axle was a major pain in the ass. The rear axle is a 12×166 (12mm in diameter by 166mm in length). The ’12’ part is standard stuff. The ‘166’ is a little unusual but still not a dealbreaker. Mix in the required P1.5 threading and thats where Google and Amazon searches go off the rails.

After a fashion, I ended up finding two of them. I ended up using the cheap one and have kept the fancy one in reserve.

The Cheap One:
Dymoece brand 175mm with 19mm thread length. Its exact specs are written right on it in the picture below. I was surprised at how well this was machined. Its 175mm length is too long, but I had a 3mm thru axle washer in my parts bins. Putting that on sizes the axle so there are 2-3 rows of threads visible coming out the derailleur side. Perfect. Everything lined up on this one from the thread pitch to the slightly longer thread length to allow the use of the washer. I like this axle because it is tool-less. I am already carrying hex keys and they’ll work just fine if I need to remove this axle roadside.

The Fancy One:
DT Swiss model 2160062210. This is a model that has a snap-on lever – that is just a glorified hex key – for removal. It looks nice on the bike, and you can remove it so nobody walks off with the thing. For me, since I am already carrying hex keys, I don’t need another one hanging off the end of the axle. I also like the fact that – on a bike that will sit out alone in public – no lever means no invitation to passersby to remove said axle. Still… its a DT Swiss part so its top quality.

Good luck trying to find details on this thing without looking deep across multiple web sites. The Amazon product listing gets it all wrong, calling it a 142mm length (which is correct for the internal dimension) and saying absolutely nothing about thread length or pitch.

Here’s what it really measures out to: 12x171L, thread pitch is 1.5 (it had better be) and thread length is 13mm.

With the shorter length and shorter thread pitch, it fits the Bullitt frame and dropouts perfectly without a washer, and the thread overhang out the drive side is minimal.

Rear Fender

As usual, I cobbled together something from parts and raw materials. Here’s what the finished product looks like from a few different angles.

This is a pretty non-traditional fender set up that does the same job as full coverage fenders without the full coverage. We’ll first cover the materials, and then we’ll discuss the assembly as a whole.

Gather Your Materials

Every bike builder should own some of this stuff: Flexible black cutting board. Unfortunately the black stuff seems to be off the market for the moment, or I am just not looking in the right places. Here is a link to something made of similar material to give you an idea of what I am talking about. What you want to do is replicate the same base material that is used for flexible MTB mud fenders. Once you have that you can cut that raw material to shape as needed.

Next, I used two of these front fenders, that I interwove together, facing each other, so they made a single longer fender. total cost for the pair – which are the core of the fender project – is US$12.84 delivered.

I created the rack deck plate and bobtail with a 1/8″ thick, 2″ x 24″ piece of 6061 aluminum flat bar stock – sold as a remnant – that cost me $8.00 on Ebay. That is way cheaper than normal. Here is a 48″ long piece that is 1/8″thick x 2″ wide. You can cut down to your needed length. Save the rest for your next project. You can go much wider than this for a rack deck plate, but I decided I wanted to go narrow for reasons that will be clear when you see the next item.

I continued to use the paint-matching duct tape that I found by accident across all parts of the rack. If your Bullitt is not the older, brighter Lizzard King color you will want to go with something different. If black works for you then Gorilla Tape is probably my favorite overall material for this kind of work, and in fact I use it here, as described below.

Put the ‘fender’ together

Its not really a fender, but rather a series of pieces that do the job of a fender.

First of all, there’s the rack deck – the bent-up piece of aluminum flat bar. Its length is determined by how long it needs to be to intercept all water spray coming up off the back wheel. I also want enough of a ‘tail’ so I can add enough reflective tape so it is a sufficiently big rear reflector. I used a relatively narrow piece that is 2″ wide. Why?

I wanted enough free space on each side so I could hook panniers to the rack. I *could* have done a full coverage deck – which would have allowed me to use a wider bobtail, and then used a router or hand files to cut out slots for pannier hooks. Frankly… it was easier to do a narrow piece and then follow up with …

Tape. The color-matching tape is nothing more than a wide series of strips folded over onto themselves to make a 2-sided sheet fully as wide as the entire rack deck. Then I bolted the aluminum flat bar on top of it. To allow for the hooks to be popped onto the top of the rack tubes, I simply took scissors and snipped the tape where there is a crossbar, to allow it to fold down when I clip panniers on. This is a bit cheesy, but it got the job done. If some time down the road I have some time on my hands and about US$30 I will cut a full width bar and slot it so its prettier than what is there now.

The rack and bobtail thus do most of the work keeping water coming up off the wheel. Now we have to deal with water coming forward. That is accomplished with the cheapie, doubled front mud fender. It is attached with small green zip ties to the seatstays, and its length in the back lifts up and contacts the rack deck. So… no water is coming forward past that. The front half of this fender also comes down and butts up against the seat tube fairly low, so there is very little area uncovered. But lets cover that too.

To deal with that last bit, I used the cutting board material and snipped out a rectangular length that is as wide as possible while still staying out of the way of my legs and the crankarms (look for it, installed, in the pics). I poked a couple of holes in the right spots and simply screwed this length of ‘fender’ directly to the frame using the two M5 bosses that are already there for fender mounting, on the back of the seatpost.

Front Fender

On the front, I cheated and found something I could just buy and install.

Godzilla uses a Greenguard-belted Schwalbe Super Moto X tire in 20″x2.40″ size. This is larger than most tires – in fact its a hair under being too large to fit the frame. Most fender solutions will not fit.

The SKS Rowdy 20-24″ fender set provides the solution. I shelved the rear fender and used only the front half of the front fender. The front mount without the fender attached is shown below.

The spacer under the mount keeps the fender from interfering with the tonneau.

Since the fender slides onto the mount bayonet via a firm interference fit, I keep the fender in my toolbag. If I need it I just slide it on. I like to be able to see the tire when riding, as part of my general need to be over-informed of every aspect of the bike as I go down the road.

In addition to it not fitting the bike, there’s no need to use the rear half of the front fender. The front of the cargo deck shields the rider from any splash coming up off the back of the tire. I did add some waterproof rubber tape to the frame at strategic locations to ensure it is a fully sealed face to splashing water.

Steering Dampener

I am using the generic Larry Vs. Harry steering dampener. I found the bike had a horrific speed wobble prior to adding the side panels, which almost completely eliminated said wobble. It only reoccurred on certain downhill road segments where there were repeated road undulations… that set up just the right harmonics for it to happen again. Installing the dampener and setting it to its lowest level cured the problem forever.

Jones Handlebars

I use Jones bars to alleviate pain from pressure on my wrists that came from getting hit by an inattentive motorist in 2017. Their 45-degree angle works wonders. They also give me a long grip area that lets me change positions, and lots of real estate to attach all manner of gadgets. An AWD ebike with one throttle for each thumb, dual PAS panels and dual displays, headlights, a dashcam, missile launchers etc. benefits from the wealth of mounting points available.

I also use two sets of Wolf Tooth Fat Paw grips. 1 and 1/2 grips per side. The extra diameter works well with my hands and thanks to those wrists, I need the extra padding. I cover the 2-piece-per-side grips with a wrap of silicone plumbers’ tape that keeps them grippy but not sticky. If I tear up the grip tape somehow (this happens rarely) I just wrap on another layer.


Long ago I gave up on trying to find a light that suited my needs, that I could wire into my main ebike battery. Instead all of my lights have their own internal, rechargeable batteries. Once a week at the office I charge them all on the same day, via a USB hub that is a part of my office garage gear.

I use my lights as daybright, daytime running lights and night use. The need to have the lights day-visible means I am going brighter than most folks’ lighting setups.

My lighting choices are informed by the knowledge that blinkie lights are the best to improve the ‘conspicuity’ (yes thats a word) of a rider, but they inhibit a motorist’s ability to track motion. So I use a combination of steady lights and blinkies, front and rear.

Front lights

Out front I use a pair of Niterider Lumina Micros for my main headlight beams. I split my headlights into two widely separated beams for the same reason cars do it. It makes for a wider beam pattern than you can get even with a dual-bulb single headlamp.

In between the two steady headlights is the front version of the Knog Big Cobber. This is a pricey light, but its also probably the brightest, smartest front blinkie you can get your hands on. It actually has an app that lets you program its modes, and I have mine set to ‘eyesaver’ mode coupled to their econ mode (short but intensely bright) blink. The Cobber lights from Knog shine in a 330-degree arc. So you want the eyesaver mode to keep from having that blink coming back at you.

Rear Lights

Out back, I have another Knog Big Cobber as my blinkie. Again it is set to ‘econ’ mode which is an intense, sharp, short blink. This time I let it ride for its full 330-degree illumination. That blinks light to the ground, to the motorist and up into the red reflector of the bobtail. Hopefully they’ll see me.

To aid said motorist in tracking my motion, I have two Knog Blinder Square lights, set to a steady illumination of the outer half of the light.

Running the light half-strength like this lets it last the full week as I like to charge everything together on Friday.

Clip-In Pedals

After literally decades of riding first toe clips and straps, and later clipless when they were introduced into the market, I have been riding flat pedals and Five Ten Free Rider sticky platform pedal shoes for the last couple of years.

I decided to go back to clipless not too long ago, and I have found the Funn Ripper pedals to be amazing. Their spring loaded cleat mechanism – the cleat sticks up and makes cleating in ridiculously easy – is a wonder. Highly recommended. I’m using Giro Rumble shoes which let me cleat in, or get off the bike and walk into a shop or wherever comfortably without clackclackclacking on the pavement.

As you can imagine, being locked into the pedals again made for an exciting transition period, and I managed to fall over at an intersection within 24 hours of making the switch. But once that little reminder was hammered home, I haven’t done it again.

So… Thats That

It seems I’ve come to the end of this somewhat tedious breakdown of all things Godzilla – The Big Green Bullitt. If I come up with any more I’ll amend this post. But, honestly I’m happy this series is done as it lets me get on with other projects I have been looking forward to, but can’t begin because this monstrosity remained unfinished.

Larry Vs. Harry Bullitt – Rear (BBSHD) Motor and Drivetrain

The Bullitt Build
1. Battery and Battery Box
2. Cargo Box
3. Brakes
4. Front Motor & Wheel
5. Rear Motor & Drivetrain (You Are Here)
6. Bits & Pieces

The Mid Drive

Godzilla is a 2wd/AWD ebike, with a Bafang geared hub motor in the front, set up as a helper to the Bafang BBSHD mid drive powering the back wheel. This is not the first AWD ebike I have built and we’re now beyond what I call my Gen3 configuration. I don’t call it Gen4 as it is still effectively Gen3, and incorporates all of the lessons I learned (and mistakes I did not repeat). Its different in that the two motors blend together in a kinder, gentler fashion I am calling Drama Free AWD.

Fitment to a late model Bullitt

Lets not sugarcoat this: The BBSHD does not fit a Bullitt. BUT… its pretty easy to rectify that. Thankfully there is very little needed to make it fit.

You will figure out for yourself what the problem is real fast. Just try and slide the motor axle into the bottom bracket. Oof… one of the threaded ‘ears’ that holds the bottom bracket clamp overlaps the frame. There are three ways to fix this. I will warn you right now: If you try Method #3 you will be brought up on charges and imprisoned.

Method 1: File down the ear a little

Thats all there is to it. The ear is quite a substantial piece of alloy sticking out of the motor casing. Just file enough of the corner off so it clears the frame. Do a little at a time with a hand file. File a bit, check to see if it clears. File some more. Check again. Repeat until it fits thru. Do this right and the motor will clear the frame and there will still be plenty of material left so there is no concern of any kind as to the structural soundness of that ear.

Figure 1 – Red arrows: Thats it? Thats it! (ignore the heat sinks. We’ll cover them later).

Looking at the picture above, its kind of hard to see exactly where I filed it, because I took a black Sharpie to the freshly exposed alloy and just blacked it out. A few months later, its worn off a touch but you still need to know where the work was done to be able to see it at all.

Method 2: Partially disassemble the motor

This method is for the Felix Ungers of the world. If you cannot bear to take a file to the motor casing… take it apart, then position it and reassemble the motor in situ. There are only a few screws involved to make this happen… but Jesus H. Christ this is waaaay more effort than it is worth in my own personal view. If you ever want to pull the motor off you have to take the damn thing apart again to get it off the frame. For me… give me the file and 5 minutes for Method 1 and I’m good.

Even so, if someone goes this route I can understand and respect the insane attention to detail such a course exemplifies. HOWEVER…

Method 3: Take a file to the frame

Yes really. I’ve seen it done. Rather than filing off metal on the motor, some folks decide they want to file down the frame instead. The thing that is in the way on the Bullitt frame is a weld seam, and I suppose that structurally, the stuff in the way is not critical to the frame’s structural integrity. But… as far as I am concerned a bicycle frame is a sacred temple and anyone who violates the sanctity of that temple… well they should be taken out and shot. Don’t do that.

How Well Does It Fit?

Once you get the motor fit into the bottom bracket, Its a great fit for the frame. One of the Lekkie (42-52T) or Luna Eclipse 42 or 48T chainrings will give you great chain line. The motor does hang almost straight down, and this looks a bit disconcerting, but the reality is you have other things on the Bullitt that hang lower. The motor is not in any way a hindrance to ground clearance unless you decide to start rolling up and/or off of curbs and such. I have never hit anything and I have never heard of anyone on a Bullitt having such a problem.


In your typical BBSHD or BBS02 installation, the secondary gear housing – just behind the chainring – is present where, on an ordinary bicycle, nothing exists. Consequently the chainring is pushed perhaps as much as 2cm outboard from where it would be. To counteract this, its common to use special chainrings that offset themselves inward to undo what would otherwise be a disastrous chain line. That fixes the chain line, but it does nothing for the alignment of the pedals underneath the rider.

If you move the chainring mounting 2cm out that means – even if you undo the misaligned chainring – your pedals are also 2cm outboard from where they would be only on the right hand side. Yeah thats right. Your pedals are not centered underneath you.

On many builds, this is dealt with by using crankarms that have a left arm that is offset outward. Typically by 18mm (like I said… “about” 2 cm). That centers your pedals underneath you. Thats the good news. The bad news is you can either use the Bafang stock crankarms – which are cast alloy and not particularly robust – or you buy quality forged crankarms – typically from Lekkie who pretty much owns the aftermarket for strong, high quality Bafang-compatible crankarms. So you get either very cheap kaka crankarms that may or may not survive a proper pedelec rider honking on them, or you spend a bundle (and get top quality stuff).

Figure 2 – Note the secondary gear housing tucked in behind the chainring on the left.

So, Forget Everything I Just Said

The Bullitt is one of the very rare frames that does not need any of this offset crankarm business. You will buy a Bafang BBSHD whose axle is compatible with a 68-73mm bottom bracket. Install that and there is enough axle sticking out the non drive side that there is no need to do anything further. Not only is there no need… you don’t want offset arms since the goal is to center the pedals underneath you. Straight arms with minimal Quack Factor will do that.

I used forged 175mm Shimano FC-E6000 crankarms meant for use with a Shimano Steps drive. They got quite a bit more expensive before the Pandemic ratcheted everything up. I paid less for both arms than you are going to pay for just one of them. In fact they are only sold individually these days it seems. Here is the right 175mm arm and here is the left 175mm arm. If 170mm is more your bag, I know they are made because here is a 170mm left arm. I can’t find a right one. Maybe you can if you want the shorter arms.

Still, the good news is you can use straight crankarms from any vendor… so long as they are square-taper (don’t shoot the messenger on the square taper part).

The Wire Tunnel

I have seen numerous BBSHD’d Bullitts where the wiring from the motor is run forward underneath the main … girder … or whatever that part of the frame is called, and then run up once it splits into the deck support. I don’t like this because it creates visible wiring. Also, wires directly under the bike are potentially subject to ground impacts. A risk I’d prefer to avoid.

Figure 3 – the wire tunnel. Note the velcro wrapping at the point the wire bundle enters the tube. This snugs it to the inside diameter of the tube.

I looped the wires up and over the drive side. The secondary housing naturally protects and hides them. The wires then cross over the top of that girder, hidden by the wire tunnel. My original idea was to use a bit of green or black furniture-grade PVC. However, early on in the build process I stumbled across ‘Duck’ Brand neon green duct tape. This is commonly found in hardware stores in the USA. Its a hobby-grade household product and not construction-site worthy, but its fine for this job.

By some miracle the Neon Lime Green color is nearly an identical match to the LarryVsHarry Lizzard King paint. You literally have to be looking at it just right to see any difference between the two. It was perfect to cover the dark green PVC pipe used for the wire tunnel. I did use two very large dark green zip ties to hold it in place. These were the closest color match I could find and, while they are not ideal, I have yet to find a better solution (including taping the thing onto the girder with the matching tape. I tried it and it looked awful).

Figure 4 – The wires look a lot more visible here than in person. Wires include both front and rear motor wiring as well as the battery charge plug (green cap).

The inside edges of the plastic PVC pipe are not what I would call ‘sharp’, but they are edged and a little more unforgiving than I would like when rubbing every day on flexible, soft wire casing. I beveled/chamfered the inside and outside edges using a quick pass with a pipe reamer. Problem solved before it becomes a problem.

As it stands, the wire tunnel protects the wires coming out of the motor that have to be run forward and up the steering tube, where they rise to the handlebars. You don’t even see any wires now the Fahrer bags are installed.

Figure 5 – With the Fahrer bags in place, what little visible electrical wiring that exists … disappears

Heat Sinks

Godzilla presently lives and works in Fresno California USA. Whats the weather like there, Ollie?

And once it starts getting hot, it stays hot…

When faced with this, you have to take steps on a variety of fronts to at least mitigate the issues that come up. Insofar as the BBSHD is concerned, I have already covered this subject in a fair amount of detail in a separate article that predates the Bullitt build and, yes I pretty much covered the motor in heat sinks just as you see in that article.

Since the crankarms are not offset on this bike, I was not able to use an endcap, but as shown in the linked article above I covered every bit of the motor I could with the things, using both the silver center sinks and the little black squares around the edges.

BBSHD Settings

The settings for the BBSHD are another subject already covered in detail. First in this article that introduces my approach to the subject, and following on with this one that covers some very minor refinements.

To jump specifically to what I am doing on Godzilla, you want to jump straight to Version 2 and look at the right-side image.

Here are the three screens below, but all the explanation for what they mean is in the linked articles above.

Figure 6 – The BBSHD settings used on Godzilla


If we’re discussing the mid drive, we have to at least touch on the rest of the drivetrain, which is integral to making the bike go places.

SRAM GX 11-speed shifter

I prefer SRAM shifters because the way they mount onto the handlebars, they take up much less real estate than their Shimano or Microshift counterparts.

SRAM GX long cage rear derailleur

SRAM derailleurs in general, once adjusted properly, seem to stay that way. There’s not much to say about this derailleur other than it just works, precisely, smoothly and reliably, does a great job wrapping chain and has no issues with the 42T big cluster I have on the back. I don’t use its clutch feature. It is able to handle a 46T rear cluster just fine, although I don’t have one on Godzilla. I do have one on another bike set up that way with the same drivetrain bits.

Figure 7 – The long cage SRAM GX is sweet!

KMC e11 chain (mid drive-specific)

When I build a mid drive bike I use a mid-drive specific chain. That is I think part of the reason why, in all of the thousands of miles I have been riding powerful mid drive builds, I have never once broken a chain. Unfortunately the e11 is frightfully expensive. Bide your time, keep your eyes open for deals anywhere in the world (particularly in the EU) and you can find an online deal.

Sunrace CSMS7 cluster: 11-42T

For all mid drive bikes I build, I prefer steel, welded clusters that are 1-piece. Such a thing is not really available in the 11s world, but the Sunrace CSMS7 is as close as it gets. It uses steel spiders and high tensile steel cogs, which is what you want for durability with a mid drive.

Figure 8 – The Sunrace CSMS7 showing off its steel underwear

NOTE: The CSMS7 has turned into a unicorn these days. I have managed to score two NOS in auctions on Ebay. One for use on this Bullitt build, and a second recently as a backup for the inevitable day when one of mine fail (I have another on my Surly Big Fat Dummy’s street wheelset). But thats it, Nobody in traditional bicycle retail has had them in stock for months.

Given global bike supply issues, there is no telling how long it will take to fix this. I have found that a Sunrace CSMX8 appears to be an excellent performer despite its alloy spiders (one is pictured below). I use this on my mountain wheelset on my Surly Big Fat Dummy and so far it has given me no trouble. Its range is 11-46T which has proven to be no issue for the (lower end) SRAM NX derailleur that is on that bike.

Figure 9 – The Sunrace CSMX8: Lighter weight scaffolding under the hood… but still steel cogs.

Rear Wheel

The core of the rear wheel is a DT Swiss 350 Hybrid rear hub. The Hybrid line of DT’s 350 is, compared to the standard 350, beefed up in just about every way. The flanges are beefier, the cassette body is steel, the internal ratchet mechanism is a solid piece rather than being relieved for light weight, and it is a 24T engagement vs the stock 18T, which gives better response while still maintaining the super strong ratchet mechanism that makes this hub almost indestructible when paired with a powerful mid drive.

Figure 10 – The DT 350 Hybrid. The Sherman tank of hubs

The rim is a SunRingle MTX39, which has a 30mm internal width – the ’39’ in ‘MTX39’ comes from its external bead width. The review of this rim over at MTBR described it as “monumentally strong” and “impossible to bend” while noting the penalty for this strength is weight. Since weight is not a factor on a twin-motor cargo bike, I’ll take that strength any day of the week. The rim has proven itself un-dingable both here on Godzilla and on the Mongoose Envoy build I first used them on.

Figure 11 – That deep, triangular, thick-walled structure makes this puppy plenty strong.

The MTX39 is commonly available in both 32H and 36H configurations. So is the DT350 Hybrid. However, at the time of my builds I was never able to find 36H hubs, so both of my builds are 32H… and they are none the worse for this choice. In particular, a Bullitt’s construction does not put anywhere near as much weight squarely over the back wheel as do for example your garden variety mid- or longtail. That makes it easier to live without 36H. 1100 miles so far in a few months and the rear rim is still perfectly true.

In between the rim and the hub are Sapim Strong spokes with brass nipples. Once again I used the expert services of Stoic Wheels to provide cut spokes to my specs.

Front Chainring

Ordinarily, I advise a builder that you have to keep the motor spinning on a mid drive, and a 52T front chainring is way too big. You’ll bog the motor as its trying to lug itself up from a stop. This is the worst thing you can do to a mid drive, and among other things is a great way to snap your chain.

Figure 12 – 52T front Lekkie Bling Ring. As big as they come.

But Godzilla proved to be an exception. The choice of a 52T chainring (in country that is flat as a pancake) was still not initially obvious. As noted in Musical Chainrings, I have a lot of chainrings available from a variety of builds. With any new bike build, I do not expect to get it right on the first try. Unfortunately I came close here (it would have been nice not to buy another one) but in the end, no cigar.

Plan A

At first, I tried a 46T Lekkie ring pulled from the parts pile. The offset was good and planted the chain in a straight line … about four cogs inboard on the rear cluster. So with that 46T ring I was spinning a little too much with good chain line, and the bike was outrunning me. Time for …

Plan B

I switched to a 130 BCD adapter and a 48T chainring. If the 46T with strong offset was too hot. The 48T with minimal offset was too cold. Now I had a big chainring; good on the flats, but with no offset, good chainline was only on the smallest cogs in the rear. That was great once I hit cruise but bogged the motor when starting from a stop… and thats very bad. Lets try …

Plan C

My third try is a Luna Eclipse body with a 48T (proprietary) ring. So, same chainring size as Plan B but with the most offset possible in any BBSHD aftermarket chainring. This felt pretty good. I was running up in a larger rear cog so my chainline was great. That kept the motor from bogging from a standing start.

Figure 13 – Left to Right: Plan B, Plan A and Plan C

But (!) … I was not able to get down into small enough cogs when I was up to cruising speed. The bike was running away from me. The only solution was to let the bike run at slow speeds as it peaked with usable cadence and effort at about 18 mph. I lived with this for awhile – and it was ok (just ok) – until I decided to finally buy a chainring in a bid to have my cake and eat it too.

So now its come to Plan D

A 52T Lekkie chainring that has the same goodly offset as was found with Plan A. I would be biasing my chainline into the upper half of my cluster. But not so much that I would be unable to comfortably use the smallest cog (as was the case with Plan C). I figured the increased tooth count would cause me to run one gear up the cluster from where I was running with Plan C, and slow my cadence enough at that bigger rear cog to still run the bike faster, while at the same time keeping a straight-ish chainline, preserve my ability to gear down to bigger cogs and up to smaller ones.

And this time, finally, I was out of parts and had to buy the thing, using my usual source for Lekkie rings here in the USA. Ouch that one smarted a bit.

My gear calculations were done on the Speed at Cadence screen at Its an invaluable resource for the thoughtful builder working out the right gears for a build.

But the money was worth it as it completed the bike. Plan D worked perfectly. This is, as far as I can see, the only time a 52T chainring works well on a mid drive build. Worth noting is the fact that this bike lives on table-flat ground, and if there were hills in its way, I would have likely had to go with a 42T front Lekkie ring.

Thats it for the rear motor and drivetrain. Lets wrap up discussion of this build with

Bits and Pieces

Larry vs. Harry Bullitt – Front Motor & Wheel

Godzilla is a 2WD / AWD ebike. Both axles are powered. Here’s everything you could want to know about the front wheel build and motor installation.

The Bullitt Build
1. Battery and Battery Box
2. Cargo Box
3. Brakes
4. Front Motor & Wheel (you are here)
5. Rear Motor & Drivetrain
6. Bits & Pieces

The Easy Way Or The Hard Way?

Lets make things as difficult as possible and do both. My loss is your gain and now you can see the results of both paths. I don’t regret this one bit (at least, thats my story). It gave me a spare wheel and motor, which is a good thing for a bike I need to depend on. I’ll lay out both paths and you decide how you want to do yours.

The Easy Way: Just Buy a Kit

In my run-up to buying my Bullitt frame kit, I looked extensively for the right 48v motor with a 20″ wind. It turns out those are pretty uncommon. Usually they are 36v, with a 250w or at best 350w rating. Oftentimes the winding is questionable as being suited for a 20″ wheel. Usually a motor is wound for larger 26″ or 700C wheels, and the torque is just not there for a little 20″ wheel build. Perusing EBay and AliExpress listings, you are often left wondering if what you are seeing REALLY is the variation you are looking for.

Still a project only capable of rolling around in the garage: the original kit wheel, with the too-wide Schwalbe 2.40″ tire on. It actually worked just fine.

I lucked out, and found posts on the Bullitt: The Dark Side Facebook group from someone who had just finished receiving and installing a complete 48v, 500W Bafang front motor kit. Based on what the posts showed, it was quality stuff. So I bought one myself: A Greenergy 48v, 500W complete front wheel kit. This kit was advertised as express-shipping from China to the USA and that is really what they did. I had it in a few days and followed its progress all the way here via the Fedex tracking number I received in my Ali control panel.

It was helpful to already have experience with Bafang geared hub motors, to understand their reliability and performance. It also helped that I knew exactly what other hardware worked with them. Particularly the display and controller I eventually wanted to use on my custom build vs. this kit.

A word on buying from AliExpress:  Its kind of an adventure.  Definitely not as convenient as buying from the USA, but if you have experience doing it, you can smell out the bad actors.  I have bought many ebike parts there - this was not my first motor shipped direct from China - and have only had a few sub-optimal experiences with low-risk, low-cost parts.  Don't fear the platform.  Its a professional operation.  But if you are going there for the first time try and buy from a source that has been recommended to you directly.  Let some other pioneer take the arrows in the back.

Up front: I knew I did not want to use the ancillary parts (controller, throttle etc.) that came with the kit. For the low price they were charging, I considered those parts throwaways and was only interested in the right configuration of motor already built inside of a decent if not especially noteworthy wheel.

Waiting in the wings:
It is present day, and the Greenergy kit wheel has a new Schwalbe Big Ben 20×2.15 belted tire mounted on it. Inside is a Schwalbe A7 tube with Flatout sealant inside. Recently I swapped out my regular wheel, described below, so I could take my time re-greasing that second motor at its current 1000 miles. The G020 motor is adequately greased from the Bafang factory, but only barely so with white lithium grease that needs refreshing every 2000 miles at best. Since the above motor/wheel was an extra I was able to pull it apart, look inside, clean it out and re-grease it with Mobil28. That grease will at the very least have triple the service life before another re-grease is in order.

Is it the best grease for the job? Opinions vary widely. Mobil28 is a favorite in the DIY community and I can say from having it in geared hubs over a couple of years it has never done any harm. The motors I have used it on have never behaved differently other than to run a bit more quietly.

The Hard Way: A Custom Wheel Build

I knew from my previous AWD builds what controller I wanted to use, and I already had all the small parts like PAS sensor and throttle. The only thing needed was a display and I had an easy source for that.

In the end, the electronics were easy. It was the mechanical bits that were tough. I had a hell of a time getting hold of the right spokes, nipples and rim. Once acquired, I had to wait about 6 weeks for my poor, perpetually-backlogged wheel builder to get to making the thing. Having the kit wheel I could just plug in was great. I was able to ride the bike maybe two months earlier than I would have otherwise.

Having just finished buying one Bafang G020 with 11T winding, I didn’t need to expend any more energy figuring out what motor to use. I just needed to find a bare one. I was able to acquire one from the same guys who sold me the kit – for just over $200 on AliExpress (and it took quite a while to arrive this time). Thats the good news. The bad news is I can’t give a link to that motor as its no longer available there. But I can display a picture of the almost-identical motor model designation, and show you what you want to see for a comparable buy for a 20″ wind:

Reading the Bafang factory codes in the image above:

FM“Front Motor”
G020Model number
500Rated for 500 watts
DDisk brake compatible
12“12T”, or 12 turns of copper winding on the motor core

My motor is 11T, not 12T. 12T could work on a 20″ wheel, as it gives you higher torque and consequently a lower top speed than 11T. However my 11T motor works perfectly as I want it to – right in the Goldilocks zone for a front motor that I don’t want to be too powerful off the line (no need to pull hard on that front fork – or the fork’s dropouts) and which starts to peter out just as the rear mid-drive starts kicking in hard, for a nice drama-free balance. A 12T motor would have a lower top speed that might make it die off below the typical cruising speed for this bike and I’d rather keep both motors working for as much of the range of normal use as possible.

Details on how the motors interact on this 2wd ebike:
“Hub + Mid Drive Cargo Beast”

Here is a link to what appears to be a very similar if not identical motor for sale on Amazon. You will want to ask the seller what the motor winding number is. Based on the similar name of the seller on the listing as of today, this may be the same one I bought mine from.

Rim Choice

For a rim, I wanted a wide BMX rim to better accommodate the plus-sized, 2.4″ Schwalbe Super Moto X (belted) tire I wanted to use. 2.4″ is outside the envelope of most Bullitt builds, but it will fit the fork easily and the frame barely. A tire that wide needs a wide rim. I chose the Alienation Black Sheep. It was the widest double-wall rim I could find. Its spoke drilling is angled, which should help when fitting short spokes into a small rim with a great big hub in the middle.

Cross section of the Alienation Black Sheep rim. Economical and really strong.

Spoke Choice

I specified Sapim Leader spokes in 12 gauge, with brass nipples. Once again I used Stoic Wheels as my go-to source for custom cut spokes in a world where you can pretty much forget about finding such things. He’s come thru for me on I think three separate builds now.

The spokes were my call. The wheel has proven (so far) able to take anything I can throw at it without any issues. But if I had it to do over again, I would not have chosen such heavy spokes for such a small wheel. They’re strong and all, but a spoke this heavy-duty did not like to be worked into a wheel this small with a hub this big. Sapim spokes are high quality and most likely the 2.3mm/13ga would have been a better choice, or maybe a Sapim E-Strong 2.6-2.3mm single-butted?

For me this is water under the bridge, but for anyone wishing to do a similar wheel build, consider carefully. My trusty longtime wheel builder at Stevens Bicycles got it done, but he said it was the most difficult wheel he has ever built. Looking at the spokes in the wheel, you can see why it was a struggle. Wheels generally derive their strength thru the rim, and the spokes need to provide some flexibility. If the spokes are too strong, there can be negative consequences. I clearly don’t have flexibility (think shock absorption) in this wheel … so fingers crossed it doesn’t come back to bite me.

Custom wheel build. 27mm double-wall BMX rim. As wide and strong of a rim as I could get my hands on without descending into fat bike territory.

Torque Arms (plural)

The G020 is rated for 45 Nm in its 350w, 26″incarnation. At best it is good for 60 Nm here in a 20″, 52v system with a 25a controller (thats set to slow start no less!). So, not exactly a powerhouse by design. You may not even need a torque arm on the Bullitt’s chromoly dropouts. But in my past I have ruined one chromoly fork and seen countless others destroyed by front hub motors. I consider a properly made torque arm essential as cheap insurance. Look at the pictures of the front wheel seen on this page and you will note that I have two of them. More is always better.

The Grin V2 arms I am using here are super easy to install and just as easy to remove if you have to pull the wheel off – just unscrew the socket cap at the dropout and the torque arm becomes a glorified washer.

PAS Sensor Installation

This was a major bit of fiddling that I have fortunately done before, so I didn’t have to do any heavy lifting to figure out how to make it happen. The job is to set up a pedal assist disc sensor on the bike, except the BBSHD is located on the drive side where the sensor goes. There’s no way to use it on that side, period end of story.

There are a couple of alternative sensors available that are meant to be usable on the non-drive side. Why is that a thing? The problem is anything meant to work on the drive side, which is moved to the non-drive side, is going to be reading rotational signals backwards, so it won’t work. Thus the left-side, or ambidextrous alternative. However this ambidextrous sensor is noisy and can fail via crud ingestion.

Using my chosen KT controller, its also possible to use one of two ‘reverse direction’ settings, so you can use a standard sensor. This was an option, but not necessary because, fortunately, I used a little trick that kills two birds with one stone: This particular sensor is held in with a screw rather than being molded in place, so I was able to simply reverse it in the mounting ring.

This not only solves the sensor-backwards problem, it also means the mounting ring is pointing in the opposite direction from normal, and now holds the sensor further out rather than tucking it in closer to the frame. That just so happens to be exactly what I want when mounting it in conjunction with BBSHD bottom bracket locking rings. You can see that in the pictures below.

What you see above on the right is an early test fit that is not complete. On the left you see the full, final setup. To anchor down the motor and then the PAS sensor ring, I used an inner ring, capped by the commonly-used dark black outer trim ring for the motor. Then came the sensor, capped by another inner motor mount ring. That third ring sandwiches the sensor mounting ring and holds it into place. My usual BBSHD installation uses two inner rings tightened together, jam nut style, but with the extra axle length sticking out of the 68mm bottom bracket, a traditional inner6+outer, followed by another inner did the trick. Stacking them like that has the added benefit of ensuring the motor never moves. The PAS sensor mounting ring is sandwiched as if it was a big washer.

Another reason the ambidextrous sensors don’t work well is they eat up about 1/2″ of real estate on the axle. As you can see on the left photo where the crankarm is torqued down fully… there ain’t no room for that here. There is however enough room to put on the standard magnet ring, and if you look closely you can see I placed a rubber o-ring on each side that in turn holds the magnet ring tightly in position, just a hair away from the sensor pickup.

Net result: Pedal assist is reliably enabled on both motors. That is a thing of beauty when you can get it to work.

Controller – Choice / Settings / Location / Wire Routing

All of my hub motors have been Bafang geared hubs, and all used KT controllers and displays. So I went with what I was familiar with. As noted above, sticking to what I know let me immediately solve the PAS sensor problem, among other things. I also already knew what I needed in terms of motor configuration within the controller so it operates safely within the confines of how I wanted AWD to operate: Seamlessly and without drama on a bike subject to extreme loads. I didn’t want this motor to be pulling hard on a bike with a potential total system weight in excess of 400 pounds.

So I knew I needed a KT controller. I also knew the 35 amp models I have used in the past were a) too strong and b) would not have the right motor plug. 35a controllers use the 3-pin Julet Z916, which matches up to the higher powered Bafang hub motors. A 500w motor has the ‘small’ HiGo Z910 9-pin plug, and KT controllers with that plug are in the 15, 20 and 25a range. I opted for 25a as I’d rather dial down too much power than to need more and not be able to get it.

However, I didn’t need to do much of anything except set the controller to max amps and slow-start (the C5 setting).

As to controller location, once again as with my previous AWD bikes I used a handlebar bag and simply set the controller inside of it, with the open top of the bag providing ventilation. This time I didn’t bother to use grommets to create reinforced holes in strategic spots in the bag. Because of the different sort of layout the Bullitt provides to the builder, I was able to simply run up a single bundled, loomed cable up and into the open top of the bag. You can see that cable in the right side cockpit photo below.

Front Controller bag with bundled cable simply exiting the open top. The velcro strap is in case I need to keep long pants out of the chain. And to hold my sunglasses

Controller settings are as follows for the G020 motor on a KT controller:

P Settings

P1 = 100
P2 = 6
P3 = 1
P4 = 0
P5 = 00

C Settings

C1 = 00
C2 = 0
C3 = 1
C4 = 3
C5 =00
C6 = 3
C7 = 1

C8 = 0
C9 = 0
C10 = n
C11 = 0
C12 = 4
C13 = 0
C14 = 2

The P settings are mostly specific to the motor hardware and not to be fiddled with, although I have P5 set to operate on ‘real time voltage’ rather than let the display try and calculate it via a half-baked method built into the controller. “Real time voltage” is just as useless, actually. Free advice: Use the LCD3’s live numeric voltage readout and ignore the graphic.

Beyond that, I will leave the settings to you to figure out (its not hard, and bear in mind I was deliberately toning down the performance of the motor, looking for smooth and drama-free AWD performance), with the following manual link:

For a complete KT-LCD3 manual translated by a native English speaker, follow this Google link for the Dillenger KT-LCD3 manual.

Display and Remaining Electrical Bits

The throttle on this bike is your basic thumb throttle. I intentionally used an old design of KT controller so I could re-use PAS sensors and throttles I had sitting on my parts pile for years. Modern KT controllers use master wiring harnesses very similar to the bundled BBSHD one-to-many wiring harnesses, and so if you are purchasing one in the present day your throttle and brake cutout connections will match to that harness.

The display I used is a simple, straightforward, old-school KT model LCD3. The LCD3 is an inexpensive old standby that does everything you could want a display to do, without the fancy bells and whistles of the current generation of color displays.

But… I would have rather had a ‘pretty’ one. The KT-LCD8H is effectively the LCD3 with a redesigned color display and layout. More usefully, its settings are all visible on a single screen and can all be edited from that one screen. The LCD3 makes you work for it the old fashioned way: One setting at a time, one screen at a time. Miss one and you have to cycle thru all 30 of them after a reset. Its not the end of the world but you only have to use the LCD8H’s settings screen once to appreciate the convenience.

Still, the LCD3 does its job and is economical. Thanks to the wonkiness of the global supply chain, the Model LCD8H was unavailable when I was in the market to get the display I needed for the Bullitt.

As seen on The Great Pumpkin – A KT-LCD3 at top and a color KT-LCD8H at bottom.

Motor Cable Routing

Last and … well, probably rightfully least is the routing on the motor cable from the motor itself back to the controller that is hanging all the way back in another county, back under the handlebars.

First of all, a connection extension to the motor cable is necessary. I bought this one from Amazon – a 60 cm extension. Between the relatively long length of cable coming from the controller, and the length from the motor, this was a perfect size. However, cable lengths vary widely from one batch of controllers or motors to the next, so have your own in hand before you decide on your needed extension length.

Many builders run the motor cable up the fork and then back down again, then running it underneath the cargo box. I wanted the cable protected from ground strikes and weather, so I ran it inside the cargo box as I did the front brake cable (more on that in the separate Bits & Pieces installment).

So not only did I run it thru the cargo box interior, I found the steering arm provided me with a shorter highway straight to that cargo box ingress point. Sure, its not a fixed mount but neither is the fork blade, which also needs slack so the fork can wiggle back and forth as you dodge potholes, run around in circles etc.

Again wanting the cable to be protected, I re-used some unused bits of 3/4″ tubing left over from what I did inside the cargo box. A couple of 45-degree elbows, a few centimeters of straight tubing and a few zip ties later, a cable tunnel was firmly attached to the top of the steering arm. The motor connection from motor to extension is housed inside this tube, and experience has shown the downward angle of the front-most elbow is enough to keep water out of the tube. Speaking of which this tubing also keeps water and crud from taking its best shot at the motor connection.

There is enough slack on both sides of this tubing, along with smooth, rounded edges, to ensure there are no motor cable pinches and no tight bends that will break down the cable over time.

And that, as they say, is that. We’ve pretty much covered everything of interest on the front motor wheel build, installation and configuration. You can use this to inform your own front wheel ebike build

Or take it as a guide on what not to do, as you please.

Thats it for the front motor and wheel. Lets talk about

The BBSHD Rear Motor and Drivetrain

Larry vs. Harry Bullitt – Put On The Brakes!

I mean that literally. We’re going to go over choosing and putting on the brakes in this frame-up bicycle build discussion.

The Bullitt Build
1. Battery and Battery Box
2. Cargo Box
3. Brakes (you are here)
4. Front Motor & Wheel
5. Rear Motor & Drivetrain
6. Bits & Pieces

For me, the choice of brakes are easy: I use Magura MT5e brakes on all my bikes and the Lizzard King was no exception. Poke around and you will see the MT5e is arguably the best ebike brakeset on the planet – even over and above the new MT7e (which provides identical calipers and brake levers… the stickers are different, plastic caliper covers are yellow not silver and the only functional difference is slightly better pads you can buy yourself – after you wear out the perfectly good ones that come with the MT5e’s).

I also use a less expensive but better rotor, as seen in the above headliner photo. But I’m getting ahead of myself here. By and large, this is an entirely mundane brake installation, with the exception of an extra-long front brake hose, plus some tweaks on pad choice. Lets begin with the…


For the rear axle, its a totally generic job. The brake hose simply runs along the guides of the top tube and down the non drive-side chainstay to the caliper. Zip tie the hose to the existing mounts on the frame and job done.

Well, not exactly. You will want to cut down the 2200mm hose that comes with the brakes, and unless you are very careful (it can be done and Magura shows you how in their Youtube videos) you will have to bleed the hoses after cutting them, then reattaching the sized hoses to the lever.

If you are using the standard Bullitt frame kit, you have a Satori Easy Up, which allows you to raise the handlebars temporarily so you don’t bonk a passenger on the head with your handlebars as you ride. When you size your brake hoses, do so with the Easy Up fully extended.

Its the front mount that needs special attention. On a normal Bullitt, running the hose the way Larry Vs. Harry intended, they specify a 2350mm hose length. I heard 2750mm in a discussion with Splendid Cycles, and I think they are more right than wrong by going long. Either number is well beyond the 2200mm provided with the Maguras in their caliper/hose/lever kit.

My needs for running brake hose from the front wheel are different than most because I had a battery box where a normal Bullitt would run its brake hose.

So this is going to be one long hose; longer than is needed on a tandem, so you are going to have limited options. If you dig around, you will find a few sources for extra long hoses. You may hear the recommendation to use one of a couple of extension solutions that use a butt-end connector to bridge two hoses. These will work, but I won’t discuss them because thankfully, I found other options:

Jagwire Pro Hydraulic MTB Hose Kit

This can be purchased on Amazon and comes with a single 3000mm hose. You are supposed to cut that 3000mm somewhere in the middle so it is enough brake hose for both your front and rear brakes. On a normal bike thats plenty of hose for front and rear. For a Bullitt its enough for the front only. You will also have to buy the hose end kit for your brand of brakes. Naturally, those are sold separately. I bought this one for Magura brakes. It should be noted the only reason I bought this is because – most likely thanks to COVID shipping delays and general global chaos across the planet – the next option listed was taking months to deliver. In the end I didn’t use this Jagwire kit because the following finally arrived:

Custom Hoses (from Austria)

Via Ebay from seller ‘judma‘. There is no telling how long this link will last… The green ones I bought are already gone and only orange and white remain for sale (for now? Maybe they’ll come back?). I didn’t want colored hoses so much as I wanted 1-piece hoses, and this seller had a particularly useful option: I could specify the custom length of each hose. So I specified 3000mm (I actually got about 2950) for the front and a lesser, specific size for the rear. Since these hosesalready had the ends properly machine-pressed on, I opted to use them. However the neon green was a little too bright. I toned it down by covering it with dull green heatshrink tubing, from the caliper to where it entered the cargo area (more on that later) and with black heatshrink after its exit into the sunshine near the handlebars. These hoses turned out to be of top quality.

A blindingly Neon green brake hose gets toned down with a dull green heatshrink as a permanent cover.

UPDATE: An Alternate Path

In discussions about this article on the Bullitt – the Dark Side group on Facebook (thanks to Arild V. for bringing this up), it was pointed out Magura sells extension hoses alone in 2500mm lengths. Thats another avenue to the same goal, then: Buy an MT5e kit, still (buying a lever and a caliper outside of the kit is much more money than just buying the kit and stashing the hose that comes with it for some future project). Then buy a 2500mm 90-degree hose. Substitute this hose for the one in the kit. You will have to have a complete bleed kit and all tools necessary to redo Magura brake hoses (you should have this anyway).

If you live in the USA like I do, this is nowhere near as attractive of an option as it is in the EU. Magura brakes and parts are double or triple the cost here. This 2500mm Magura hose in the USA runs about US$65-US$70.

After this discussion I decided to go measure my brake hose on the bike to figure out just how much I cut it down from its original 2950mm. I came up with 2670mm. Could 2500mm work? I’m sure it can for a normal Bullitt. When looking at my hose lengths, remember I had to re-route due to the battery box. This means the hose exits the corner of the cargo box and runs around (and is protected within) the concave rear edge of the honeycomb floor. It comes forward to the steering tube from the inner rear edge of that floor and only then begins its run up the steering tube. That adds several centimeters to the necessary hose length…

Which I didn’t care about as I had plenty of hose to start with. If I had only 2500mm to work with, I’m not certain I could have made internal routing work. Something for you to take into account and puzzle through when you do your own project.

Worth Noting

In my initial build, up front I was able to make the stock 2200mm hose that comes with the Magura MT5e brake kits work – and work pretty well. Look at the picture above and pretend you are seeing the stock black hose… I ran the cabling inside thru the cargo bay as you see above, and let it sit naturally along the lower edge of the floor (it’ll stay in the channel created by the edge of the honeycomb floorboard just fine). As it curves back up to the handlebars along the back of the cargo box, it did so in an arc right along the rear bulkhead. Flush to it. Nothing sticking out.

Fitment was fine, with nothing really extra but nothing stretched, either. The hosecame up along the rear wall, out of the cargo box along the extended handlebar stem and then to the brake lever. I added a couple of zip ties to keep it snug to other hoses and completely unnoticeable.

I ran the brakes this way for a couple of weeks while I waited for the longer cabling to show up, and I could have lived with it being like that permanently if I had to. However, if I had needed to raise the Easy Up to accommodate a passenger I might not have been so sanguine about this lazy solution.

Rotors & Pads

The choice of rotors to go with the MT5e’s is a little gimmick I really like. Generally bike owners shopping for rotors only concern themselves with rotor diameter. 160mm, 180mm, 203mm… those numbers sound familiar, right? But what about how thick the rotor is? Well, Tektro type 17 rotors are 2.3mm thick.

So what?

Your typical bike brake rotor is 1.8mm thick. Some brands will shave that down to as little as 1.4mm (Avid rotors were thin like this years ago when I was still using them). A thin rotor is lighter and thats nice for your skinny analog road bike. But a great big ebike? Not so much. You want meat on those rotors just like you want great big brake rotors on your race car. Brake rotors are heat sinks and braking is the process of converting momentum to heat. The more rotor you have the more heat it can absorb. The beefier and thicker your brake rotors are, the more it takes to warp them. Or for that matter wear them out.

My initial front wheel build used a 180mm Magura MDR-C rotor

So, one of the reasons I like Magura calipers is they are designed to take an unusually thick 2.1mm Magura brand rotor. Great. The Magura Storm HC rotor, or its new beefier cousin the MDR-C, are designed for the MT5e/MT7e, and vice-versa. These 2.1mm rotors are considered worn-out when they get to 1.8mm – thats the size most other rotors are sold new. Magura calipers should NOT be used with thinner industry-standard rotors. Thinner rotors extend the pistons too far and could cause them to leak. Do not ask me how I know this.

But what about thicker ones?

At last! We get to the point. I’m using 2.3mm thick Tektro rotors, which were originally meant for the small niche of downhill MTB bikes. Now they are sold by the boatload as ebike rotors with Tektro’s newfangled ebike brake kits.

Is 2.3mm too much for the Magura caliper? Almost, but it works. Since I have so many sets of Magura brakes on The Pacific Fleet, I can pull a set of partially used pads off of one of them, plug those still-usable pads into a new bike build, and let the slightly worn pads give me an extra skootch of clearance. When these pads have worn down and need to be replaced, the fat rotor is now worn a bit and can handle fresh pads easily.

I have yet to wear out one of these Type 17 rotors down to 1.8mm thickness, which is not something to complain about.

On the Front

So, on the front wheel the rotor is the 203mm size. Thats a lot of rotor for a 20″ wheel. I initially used a 180mm Magura MDR-C, coupled to Type 9 Performance (Black) pads. those are the ones that come with new MT5e calipers. I found this combo could easily lock up that poor little front wheel. I was already building another custom front wheel, so the final wheel build used a bigger 203mm Type 17 (even more stopping power, which is not so great) but with downgraded Magura Type 9 Comfort (Blue) pads – a lot less stopping power but great modulation and longer lasting.

My original – now backup – wheel is waiting in the wings with a Tektro rotor already installed. I’ll swap it onto the bike soon so I can take the primary motor apart and regrease it without disabling the bike in the process.

The pads were expected to be so much less aggressive that they would more than make up for the bigger rotor, and thats exactly what happened. I still have strong braking performance on that front wheel but now its very nicely modulated so I can clamp down hard without locking up the front wheel and making a spectacle of myself.

Since the Comfort/Blue pad compound is not sold in a Type 8 4-piece pad, I considered replacing them once they wore out with the Type 8S (Green) ebike pads. Still a step down from the Performance/Black compound, but the 4-piece pad config would step up the torque the calipers can apply to the rotor. Hopefully not too much.

That was the plan, and maybe it is something you want to try with your build. But the day I was to publish this post, I performed front wheel maintenance on the bike and saw the pads are down to about 1.5mm already – time to replace them in a couple weeks. The market is such that the Type 8 green pads are very pricey, and the Type 9 pads are dirt cheap from a German bike site. So what the hell I stuck with what I know already and bought 3 sets, along with another cheap Super Moto X tire (also very pricey if bought from a USA source) to soak up the $20 shipping charge and still keep me ahead of the game on costs.

On the Back

The rear rotor is, at present, a Magura Storm HC 203mm rotor. Its a solid choice for a rotor, and of course its the go-to until recently for a factory-matched kit. Why use it instead of the Type 17? Frankly it was in my parts pile and needed to get used up. So instead of playing the pad-swap game described above to fit a fat Tektro rotor, I put on a factory rotor and we’ll wear down the pads some thataway. After 1000 miles on the bike, it is already down to 1.9mm from its original 2.1mm. It won’t be long. Don’t blame the rotor: cargo biking is as severe of a duty cycle as you can get. I use the rear brakes as my primary stoppers with the fronts eased in after the rears engage. I get well-balanced rear brake wear as a result.

This 203mm rotor is taking a beating and will be replaced sooner rather than later with another of the big Tektro’s

Out back I am using the standard-issue Magura Type 9.P pads – the black Performance compound. Ordinarily I only use the Type 9’s initially as they come with the new calipers. I then replace with the more torque-y Type 8.P’s from then on. But here again I have Type 9’s in my parts pile so I am just using this bike to run through them. They work just fine, although to replace them or check pad wear you have to remove the caliper from its mount, which is one more reason why you want to use MT7 pads (a.k.a. “Type 8”) in your otherwise-identical MT5 calipers.

Brake Cutoffs

This bike has a Bafang mid drive powering the back axle, and a Bafang hub motor with KT controller powering the front. In my 2wd twin-hub-motor builds, I split the cutoff signal from one lever to both controllers on each lever, so actuating either lever alone cuts both motors.

I learned with the 2Fat build that trying this with a BBSHD and a KT hub controller bricks both motors – they never can start in the first place. I tried every kind of setting or workaround and they have to be entirely separate circuits or you get no motor power period.

Trying it again on this Bullitt build, a few years later: same result. The solution is for the rear brake lever to cut the rear mid drive and the front lever to cut the front hub.

One difference from the past is now, in 2021 I am able to buy a BBSHD wiring harness designed to use Magura’s red Higo/Julet plugs natively without messing around with finding or fitting adapters. Otherwise, you have to buy red-to-yellow Higo/Julet conversion plugs. Before the above direct connection wiring harness existed, I used these little jewels.

Thats it for the brakes. Lets talk about

The Front Motor and Wheel

Larry vs. Harry Bullitt – the Battery (Box)

A big bike with two motors needs a big battery. Lets take advantage of the frontloader design to both hide and secure it.

The Bullitt Build
1. Battery and Battery Box (you are here)
2. Cargo Box
3. Brakes
4. Front Motor & Wheel
5. Rear Motor & Drivetrain
6. Bits & Pieces

A big issue with an ebike – particularly one that is left outside on its own all the time – is battery security. The battery is maybe the most expensive component on an ebike and its a big theft target. So typically you have to carry the thing inside with you, and hey… thats a real pain in the neck. Not only is it a really heavy black brick, but you have to dismount it and re-mount it to the bike, and disconnect and reconnect it to the motor (forget about your display keeping the correct time and date), every single time. I have come up with my own way to make the best of this bad situation for my other cargo bikes, but with the Bullitt, we can make the problem go away.

The Kinda-Secret Compartment

Take a look at the picture above. See the big black box under the cargo area, near the ground? Thats it: the battery box. You’d be surprised by how many people don’t notice it. Even if they do, what are they going to do about it?

I had seen a few other Bullitt builds with battery boxes and they seemed like great ideas: The battery goes out of sight, out of mind under the floor of the bike. It lets you get creative on battery size (as in you can go bigger if you like since there’s lots of room down there). It may even be made secure enough that you can just leave it on the bike – eliminating maybe the biggest inconvenience of using an ebike for daily errands and shopping.

Also, just as with electric auto designs, a ‘skateboard’ config for the battery puts it centered and below the floor – down as low as it can go. That is as good as it can get for performance.

But I was thinking of none of these things when I was putting together my build sheet. I was still thinking I would do another quick-carry sling pack with the battery inside, and toss that pack into the cargo bay for easy removal and replacement. It wouldn’t be secured to anything but I would see about figuring that out later on.

My sling pack with a 20ah battery inside, used on my Surly Big Fat Dummy

But while the parts were still trickling in, I was participating in a discussion on the Bullitt Universal Owners Group on Facebook. Another Bullitt owner showed off his own build and mentioned his battery box – and that he had gotten it from Splendid Cycles – the same shop where I got my Bullitt frame and parts. I gave them a call and in short order one of the last examples they had on hand was on its way to me. I was told up front the box was a blank canvas, and I would need my own elbow grease to add mounting holes and any other refinements, such as waterproofing, cable exits etc.

As-delivered, the battery box looked as you see it below. A simple slot holds it up on the back. Its front at first seems unnecessarily complicated, but is quite clever. Its seamless, unbroken face prevents any direct channel for water ingress from the front, just behind the tire. The cutouts necessary to let the box slide into place doubled as my exit points for the power, charging and temperature sensor cables, so no need to cut any holes. It fits absolutely flush to the near side of the frame so no insulation is needed or wanted. Its shape is angled on one side to clear the steering tube.

The box as-delivered, almost. I used black flexible silicone sealant to all the internal seams, and dabbed over all of the rivets as well.

Box Installation

The first step was to drill the box so it could be fixed in place. As-designed, it would stay put. But I am sure there would be some shifting and rattling… and I can’t abide rattles. Also, the existence of the box complicated the installation of the honeycomb floorboard. The floorboard expects to be able to drop a bolt straight down and use a nut underneath to lock it down. Well, now that bolt hole is completely inside the box on the front left corner. Its outside on the right front, but not by much. I needed to change those two mounts to fixed studs going from the bottom up.

I also wanted to add an entirely separate bolt on the front dedicated to strongly fixing the box in place. I decided to use an oversized hole, and used a hand file to enlarge it to a rectangle. Following that, a combination of an oversized, hardened washer and a flush-fit M8 bolt gives a flat fit that works under the honeycomb board fitting directly down on top of it.

The new ‘studs’ are common, long M6 socket caps with – get this – a Presta valve nut to hold them in place. I needed a low profile nut and there’s nothing lower-profile than the common presta nut, which even fits snugly inside the bolt hole manufactured into the LvH honeycomb board.

Forward box mounting complete. Two studs are ready for the honeycomb board, and the center bolt holds the box tight to the frame.

For the rear of the box, to match up with the honeycomb board’s rear mounting hole, I had to use another M6 rather than go with another big M8. I drilled a thin hole thru the box’s top flap and the honeycomb board’s rear mounting bolt goes thru there. However to be consistent – because I wanted to use security nuts to make getting into the box that much more difficult – I made it go in from the bottom-up like the others (we’ll show those security nuts etc. in more detail when we talk about the cargo box installation).

Now Install The Battery

At this point, the next step in the installation process – which, maddeningly, has to be done in this order whether you like it or not – was to install the battery.

You can see how I accomplished that below. All of the padding is closed-cell, and I left as much of the battery untouched by foam as I could. The battery lays on the bare alloy of the box with no padding (a solid metal wall is plenty of protection). It is surrounded on four sides such that it cannot move, even after months of pothole pounding commutes and store visits. I disassembled the bike after 500 miles and looked inside to be sure of this. No water had gotten in either despite riding in rainstorms.

There is a brake cable braze-on above the pack underneath the center bar. It is perfectly positioned to smash into the cells underneath if the pack bounces up to meet it. I prevented this possibility via some left over Minicel T600 EVA foam (you’ll see what I used it for in the Cargo Box episode) to fix the battery in position (i.e. keep it from bouncing). Two pieces are used, one on each side of the braze-on. Underneath this area the visible green rectangle is a piece of thin metal fence strapping which provides a last but certain line of defense against that braze-on ever contacting the bare pack.

The battery is literally incapable of movement on any axis. It is held solidly – but not enough to smoosh anything. Rapping on the box with your knuckles yields a satisfying thunk as if you are rapping on a solid block of metal.

Notice the short extensions in the pics above? There are two lengths of them in use (strictly speaking there are three as we need two when we split the power to run to both motors). I don’t like to make direct connections to wiring that is a hassle to repair – like wires that run hot directly from the battery. I want to be using a short extension on each side of a connection for two reasons. 1: So the wear and tear occurs on something that is easy and painless to replace if it wears out. 2. If something terrible happens like a short, the melted connector is on an extension and can be easily unplugged, thrown away and replaced. No need to be working on live wires to salvage the battery (assuming a short doesn’t cause other problems with the pack itself).

I have had one occasion where this saved my bacon when an XT60 extension shorted on a water bottle bolt head. There was no damage other than to the destroyed cheapie extension. In this case, there is no issue of frequent connects and disconnects, but the habit of using extensions for the safety angle is hard to break.

Lets Talk About The Battery

An AWD bike needs a lot of power. Even one where I have toned down the power to civilized levels. You must have a pack whose Battery Management System is strong enough to run two motors at once, and if you get into the subject and learn the specifics, you will find out real fast that commercially-manufactured battery packs can’t cut the mustard (this is why commercial AWD bikes have two separate batteries). If you want to build the bike right as opposed to building it cheap and sucky, you have to get yourself a custom pack built that is tailored to the job.

Pack Details

The battery itself was built custom to my specs after some discussion with Matt Bzura at Bicycle Motorworks. This is one of several packs I have purchased from his firm, after hearing nothing but good things about his work from other builders over the span of a few years. I’ve had nothing but good experience working with him as well.

I knew that an AWD bike needs more power, so the battery pack needs to be bigger than usual. And the Splendid Cycles battery box is a big sucker. If I put in a battery that filled that box it would be TOO big. Looking at the box dimensions and knowing what I wanted to do for crash padding gave me one half of the picture. Matt @ BicycleMotorworks filled in the blanks with the dimensional details of the cells and battery management system chosen for the job.

Cells Samsung 40T (21700’s)
Pack Config 14S8P (52v)
BMS Capacity 70a Continuous output
Amp Hours32
Output CableXT90S / 8ga
Charge CableXT60 / 12 ga

The 40T cells in the larger 21700 size, and overall pack design allows it to operate under load without voltage sag, and without heating up, despite the enclosed space and the dense, closed cell padding that holds the pack fast. A temperature sensor is attached to the pack top and runs outside of the box for easy visibility from the saddle.

What About Heat? 
In use in a normal climate - bearing in mind its sealed in a big metal box - the pack does not get noticeably warm over and above ambient air temperature - nothing over 5 degrees Fahrenheit above ambient.  However, 5 degrees over ambient is a lot when its 105 in the shade, where in the sun, the pavement is radiating heat at 130.   In severe heat (as I write this, the end of next week is scheduled to reach 114°F, which is more than 45°C) I need to plan ahead for where the bike is going to be parked, and plan my route to provide the shortest, shadiest path to my destination.  Our local area has already experienced several days where the temperature has exceeded 110°F / 43°C. Even though the battery cells are not thermally coupled to the case, I ringed the box with heat sinks to help keep the pack a bit closer to ambient temperature.  They have reduced pack surface temperature by up to 5 degrees. 

The battery charge cable is routed outside of the box along with the power cables, and comes up as shown in the photo below (the green plug). This plug is semi-rigid thanks to the manner in which I insulated the end connector, as well as how its braced against other secured wiring. It is easy to access, protected from the elements via the plug cap and not going anywhere. In winter months a rubber band and some plastic will ensure nothing can get through and cause any fireworks.

And last but not least… this is a 52v battery that has a capacity of 32 amp hours. I like having batteries big enough that range anxiety doesn’t exist. You simply go ride the bike and do what you need to do. Considering the bike – thanks to its motor configs – eats only 400-500w at cruise… my ass will wear out in the seat before the battery charge does…

So long as I remember to charge it. But even then – and this has happened to me already – the battery is big enough to maybe rescue me from that faux pas.

The battery temp sensor sits here, without any need for actual mounting. The Bullitt’s ride is so stable nothing more is required. The charger plug is covered in a green cap at center.

Thats about all I have on the battery and battery box. We’ll stick to the same area of the bike in the next article in the series, as the two are linked together:

The Cargo Box