📐 Will the Bafang Mid-Drive Motors Fit on Your Bike?

Bottom bracket fitment at a glance: threaded shells fit; press-fit shells need an adapter

The BBS02 750W and BBSHD 1000W bolt into your bike's bottom bracket shell — the tube at the base of the frame where your crank arms and pedals attach. If the motor fits that shell, you're 90% of the way to a working conversion. Here's how to know.

✅ Quick answer: If your frame has a threaded (BSA/JIS) bottom bracket in the right width, a Bafang mid-drive will fit — order the BBS02 750W for 68–73mm shells, or the BBSHD 1000W in the width that matches your frame.

The one spec that matters: a threaded bottom bracket

You need a threaded (BSA/JIS) bottom bracket shell — also called standard threaded, English, British, square-taper, or sealed-cartridge. Inner diameter is roughly 33.5–35mm. Match your shell type and width to the right motor:

Threaded (BSA/JIS), 68–73mm — ✅ Fits BBS02 750W & BBSHD 1000W (standard). The vast majority of road, hybrid, mountain, and cruiser bikes.
Threaded, 74–100mm — ✅ Fits BBSHD 1000W (wide / fat-bike). Order the wide BBSHD.
Threaded, 101–120mm — ✅ Fits BBSHD 1000W (extra-wide fat-bike). Order the extra-wide BBSHD.
Press-fit (PF30, BB30, BB86, BB92, BB95, PF92, BB121) — 🚫 Not without adapters. These shells are wider, unthreaded, and press the bearings straight into the frame, so a Bafang unit can't thread in. Third-party thread-in adapters exist, but we don't supply them and can't guarantee the result — take a press-fit frame to a local bike shop before you buy.

Three things that trip people up

Measure the frame shell only — not your cranks or spindle. Pull the crank arm off (or eyeball where the frame tube ends) and measure the bare shell width.
Chainstay clearance. Wide, flared, or bulbous chainstays sit right where the motor body lands. If yours are chunky, you may need to size up (e.g. run the 74–100mm BBSHD on a 100mm-ish frame). Our motor templates show you exactly this.
Frame obstructions. Non-round shells, welded tabs, cable guides under the BB, or aggressive weld beads can block the motor from seating. Most are removable or can be filed smooth — but check first.

Measuring the bottom bracket shell width for a Bafang mid-drive installation

Bottom bracket shell types and obstructions to check before installing

Still not sure?

Print the actual-size motor template, cut it out, and slide it into your empty bottom bracket shell. Or just take the Fitment Quiz — we walk you through it with videos. Still stuck? Email us your bike's specs at info@bafangusadirect.com and we'll help.

Reminder: mid-drives run on either 48V or 52V batteries — both work great on the same controller. (Only the front hub kit is 48V-only.)