Sully's Standard Tips for a Bafang BBSHD E-Bike Conversion
Jon Sully
8 Minutes
A practical, experience-backed guide to building your own Bafang BBSHD e-bike — covering motor choice, chain setup, programming, screens, and all the small details that make a conversion smooth, reliable, and fun to ride.
After authoring a custom programming for the Bafang BBSHD (and BBS02!), building several conversions, and helping lots of folks through their own conversion process, I’ve realized I ought to write out some helpful tips for all to find. So, here are Jon’s standard tips for attempting a BBSHD electric bike conversion process. Your mileage may vary and these tips imply to warranty 😜 but as always, send me an email and I’ll be happy to help as best I can!
Note
When linking to products in this post, I’m going to try to link to Johnny Nerd Out’s online store. John has been a very reliable seller, has the best prices I’ve seen around on these things, and is an honest guy as far as I can tell. He doesn’t know me from Adam but I’ve appreciated his Youtube insights, web store honesty, and flexibility in product selection. You can probably find these products at other stores — feel free! These aren’t affiliate links or anything.
Buy UART, Not CANBUS
First and more importantly than any other tip on this list: ensure that you’re buying the UART version of the Bafang BBSHD, not the CANBUS version. The difference is in how the two motors communicate with their screens and other devices as well as the base firmware they run. The very short version of this story is simply that the CANBUS motors are far more difficult to program and not nearly as flexible as the UART motors. Neither my programming, nor any of the programming of BBSHD users over the last decade, work on the CANBUS motors ‼️.
Reputable dealers are listing UART motors and CANBUS motors separately, so ensure that you choose carefully and don’t end up with a CANBUS motor!
You Need A Solid Chain
It’s important to understand that a mid-drive motor (any mid-drive) operates by tugging on your chain in a similar way that human-powered pedaling does. It just does so with much more force than most humans can exert. Standard bike chains weren’t designed for that level of power. There are many stories out there of folks running a BBSHD in some kind of high-powered programming on a ten- or eleven-speed chain and cassette where the chain snaps. It happens!
The functional premise here is that as you add gears to your cassette, the space between each gear shrinks. So too does the width of the chain and its required clearances, then. So a chain made for a 7-gear cassette is much thicker than a chain made for an 11-gear cassette. Going even further, a single-speed chain (made either for single-speed hubs or internally-geared hubs) is super thick!
All of that to say, if you’re going to do a BBSHD conversion, even when planning on using fairly human-esque programming (like mine!), you’re going to need to be intentional about your cassette and chain. KMC makes a solid, standard chain for 6, 7, and 8-speed cassettes. I personally wouldn’t go any thinner than that. Of course, that means you need to actually be running a 6, 7, or 8 speed cassette. So this begins to have implications around the drive-train as a whole. My personal recommendation is indeed to run a low-gear cassette or an internally geared hub (with a single speed chain).
Let me get ahead of the comments: can you run a BBSHD on a 10+ speed cassette? Sure. Just understand the dynamics at play here! That’s a lot of force through your chain. I don’t recommend it, but lots of folks do it completely fine. YMMV.
Don’t Shift Under Power
This rule applies to all bicycles and the skill of cycling well in the first place, but it’s especially applicable when you’ve got a motor capable of nearly 2kW of power under your seat! Don’t shift under power!! If the motor is pushing wattage through the chain, regardless of what chain you’re running, don’t shift!
Chains are weakest when the derailleur is pulling them diagonally onto another gear. If your chain is going to break, it’s almost certainly going to be at the moment when you change gears while the BBSHD is pushing 1000 watts through it. Don’t do it!
The right answer here is to setup a mechanism that ensures motor power is cut briefly when you need to execute a gear change. There are three general options here, two of which are bad. The brake-sensors and the shift-sensors are bad. They’re unreliable, sometimes janky, and require a fair amount of effort to install while failing to operate well long-term. Not worth it! I’ve come to prefer and use a cutoff button instead. It’s a $9 little button you affix to your handlebars and use similar to a clutch in a manual transmission car. At the same moment my right hand reaches for the gear-change lever, my left hand taps the cutoff button. No need to press the cutoff button early and hold it, etc — I just tap it at the same moment I shift. The motor power will come back online after one or two hundred milliseconds, at which point the chain should already be seated on the new gear. It’s far simpler, incredibly reliable, and works excellently.
Bonus: you can hold the cutoff button down to ensure the motor won’t kick in during slow situations… like being in first gear with a passenger on the back and slowly navigating through a public event / fair / food trucks / whatever. The times when you’re deliberately moving slowly and carefully and don’t want that motor to jump in and lurch you forward 😅
Chain Ring Sizes
The stock chainring that ships with the BBSHD is very average. The chain line it sets up actually tends to be pretty decent, but depending on your application, 46 teeth might not be the right proportion for your desired road speeds. I personally prefer running a Lekkie BlingRing. I’ve found the sweet spot for most builds is 42T, which gives an ideal balance of low-end torque and comfortable top speed (~20–25 mph). Anything bigger and you’ll lose climbing power; anything smaller and your top speed will feel uncomfortable on town roads.
If you’re building a cargo bike or hauling kids, the 42T is perfect. If you’re building a commuter or road-style rig and don’t carry much weight, you could stretch to 46T. Just make sure your chain line will still work. I’ve found Lekkie’s products to be worth their cost!
Program your motor
You’ll want to replace the stock programming immediately. Out of the box, the BBSHD behaves like a twitchy dirt-bike throttle strapped to pedals. Reprogramming turns it into a perfectly tuned e-bike — smooth, powerful, intuitive. Use my BBSHD programming guide as your baseline, or, if you prefer, there are several other major guides to various other riding styles out on the internet!
If you enjoy pedaling, you’ll want assist levels that complement your legs, not overpower them. That’s what my programming aims to achieve: an electric bicycle that’s still a bicycle. It rides with you, you don’t ride it. There’s a difference! Don’t suffer with the stock programming.
“Programming” a BBSHD is actually not programming at all. It’s simply plugging in a cable and changing some numbers in a webpage! More on that next.
Note
Some Bafang resellers ship their own programming already installed on the motors — Luna, in particular is known for this. It’s not magic. They just plug in the motor and change the same dials and knobs before they ship it to you then call it their “special programming”. It’s not. It’s just a few input fields they put their own number preferences into.
Eggrider or USB Cable
So, when it comes to ‘programming’, there are two primary ways to reprogram your BBSHD: on-the-go with an Eggrider display, or at-home with a USB cable. I’ve done both and both work great! The only real differentiator is if being able to tweak your settings on the go is important to you. I’ve maybe actually done that twice over the last year so… it’s not that important. The $15 USB cable is a safe and easy way to go.
If you like tinkering, get the Eggrider; if you like simplicity, the cable is all you need.
The important part is that you actually do pick one. I’ll repeat myself: don’t stick to stock programming. You buy a configurable motor so that you can configure it!
Screen Choices
The 500C is my go-to for most builds — clean, compact, easy to read in sunlight, and doesn’t make your handlebars look like a spaceship. As previously mentioned, the EggRider V2 is great for programming but also a fantastic option if you just want a small screen / discrete setup.
Tip
The EggRider is actually built into the Bafang SW102 display, so if you like the tiny size but don’t need the Bluetooth / smarts, see if you can find an SW102. They’re hard to find and always have been, but they’re usually fairly cheap and a great option.
One extra note on the EggRider — if you do want a bigger display from time to time, your phone can act as a real-time secondary screen via Bluetooth. I don’t, but you might!
If you prefer bigger, more feature-rich screens like the 860C or DPC-18, that’s fine too. My opinion just leans more toward less screen and less clutter! Wattage, speed, assist level, battery voltage, done.
Stabilizer Bar + OneNut
The BBSHD is a torque monster. Left unrestrained, it’ll literally twist itself in your bottom bracket shell over time — chewing the paint, gouging the metal, and working loose. Bafang’s stock two-nut lock ring system is bad. It bites into your bottom bracket shell and causes permanent damage while not actually holding the motor in place long term. The default lock ring has teeth:
That, when torqued down to spec, actually bite into the metal of your frame’s bottom bracket shell. Note the bite marks around the opening in the shell in this image:
Those are permanent. Worse, if the bites start slipping, there’s no more metal to stop them. The motor will eventually rotate without resistance. There’s no way to recover or fix your frame at that point. 😬
The alternative is far better and simpler: a stabilizer bar and a Lekkie OneNut. The stabilizer bar allows you to halt the rotational force by strapping the stabilizing arm to your frame itself rather than biting into your bottom bracket frame. It’s simple and elegant. The OneNut replaces the two flimsy rings with one solid, locking mount that actually stays tight. It’s the combo I use on every build and have never had one come loose. Highly recommend.
Comments? Thoughts?
kcattattam
STILL no comment about running singlespeed? You’re so close now, with all the verbiage on using a singlespeed chain (which also costs way less btw). Just need to add some verbiage on how the stock 46t chainring is awesome when not shifting, and lasts much longer than an aluminum one (as long as the chain is replaced when worn, good thing singlespeed chains are much cheaper than fancy chainrings).
The only caveat is ghost pedaling – but some of us don’t mind ghost pedaling at higher speeds (i.e. 20mph+ with my chosen gear ratio of 46x17).
Of course, to each their own. Cheers for the writeup
kcattattam
STILL no comment about running singlespeed? You’re so close now, with all the verbiage on using a singlespeed chain (which also costs way less btw). Just need to add some verbiage on how the stock 46t chainring is awesome when not shifting, and lasts much longer than an aluminum one (as long as the chain is replaced when worn, good thing singlespeed chains are much cheaper than fancy chainrings).
The only caveat is ghost pedaling – but some of us don’t mind ghost pedaling at higher speeds (i.e. 20mph+ with my chosen gear ratio of 46x17).
Of course, to each their own. Cheers for the writeup
Jon Sully (Author)
I don’t recommend running single-speed with the BBSHD! Keep in mind that I like pedaling with my bike — so much so that I built a programming all around that (cadence-value-based). Single speed would mean that, while maintaining a comfortable cadence, you’d only be able to go one speed. So.. if you’re against ghost pedaling (I am) but want to pedal co-operatively with the motor (I do), then single speed is actually not a good choice!
Fair point though about the stock chainring being totally fine when not shifting, aside from it being a heavy bugger. I still went with the 42 because the ratio with the 46 was a little high on my IGH bike, but it’s a small tweak!
Cheers for the comment! Glad you’re finding what works for you!