Bafang Mid-drive motors are designed to fit in a bike's bottom bracket shell. In order to see if your bike will be compatible with a Bafang mid-drive motor, you will need to find out the type and size of your bike's bottom bracket.
What is the bike's bottom bracket shell?
A bike's bottom bracket is the frame tube where the cranks are installed:
What type of bottom brackets do our Bafang motors fit?
The Bafang mid-drive motors fit bikes with standard JIS-BSA bottom bracket (also known as standard threaded, sealed cartridge, square tapered, English or British). These bottom brackets have inner diameters of approximately ~33.5-35mm.
⚠️ Bikes with Press Fit bottom brackets (PF30, PF92, BB30, BB86, BB92, BB95, BB121, etc.) have wider diameters and do not work with the mid-drive motors as is. You would need to find an adapter (that reduces the bottom bracket inner diameter to ~34mm, also known as a BSA threaded adapter) that works with your specific bike in order to install these motors on a bike with a Press Fit bottom bracket. Unfortunately, we do not currently offer Press Fit adapters. However, you can search for them online or at a local bike shop.
🚧❗️Unfortunately, Press-fit (and other non-standard diameter) bottom bracket bikes are more complicated than standard bottom bracket bikes as they have a wider inner diameter, so they require an adapter. Standard JIS-BSA threaded bike bottom brackets do not require an adapter, and you simply take out your bike's existing bottom bracket and slide in the motor. Unfortunately, we do not sell adapters for non-standard bottom brackets and you would have to research whether there is an adapter for your specific press-fit bottom bracket to reduce the diameter to a standard JIS-BSA bottom bracket. Unfortunately, we cannot guarantee fitment on bike's with press-fit (or other non-standard) bottom brackets due to their more complicated installation and need for adapters.
What width size bottom brackets do our Bafang motors work with?
Our BBS02 750W mid-drive motors fit bikes with 68-73mm wide bottom brackets
Our BBSHD 1000W mid-drive motors come in three sizes and fit bikes with: (1) 68-73mm bottom brackets, (2) 74-100mm wide bottom brackets, and (3) 101-120mm wide bottom brackets.
How do I measure the width of my bike's bottom bracket?
Measure your bike frame's bottom bracket shell only and not any of your crank hardware as shown in the photo below:
How do I find out what size and type my bottom bracket is?
You can search online for details about your bike's bottom bracket. Many manufacturers list the size and type of bottom bracket that come with specific bikes on their website listings. You can also contact the bike manufacturer directly.
❗️We always recommend measuring your bike's bottom bracket to confirm the size on your end.
🚧 🚨 Beware of Chainstay/Bottom Bracket Obstructions when ordering the correct size motor for your bike!!
Chainstays can sometimes really cause headaches when deciding the correct size motor for your bike. If your bike has wide chainstays or ones which flair out from the bottom bracket, it can cause issues with the motor correctly sized for your bottom bracket width not being about to fit in your bikes bottom bracket. In order to prevent these chainstay clearance issues we recommend checking if your bikes chainstays flair out before placing your order. If they do, we recommend ordering the next size larger motor (e.g. a 100mm bottom bracket motor for your 73mm bottom bracket bike or a 120mm bottom bracket motor for you 100mm bottom bracket bike) along with spacers for a successful installation.
Chainstay Obstructions Example:
Bikes with 100mm bottom brackets sometimes actually require 120mm motors due to fat tires causing the chainstay to flare out and cause clearance issues. If your bike's bottom bracket measures 100mm and you're not sure if your chainstay will result in conflict, we always recommend ordering a 120mm motor in order to prevent this clearance issue as you will either have to buy a new bike or a new motor!
Bottom Bracket Obstructions Example:
Bikes with any non-standard frame shape near the bottom bracket such as tabs under the bottom bracket or extra fat/bulbous frame shapes around the bottom bracket that would interfere with sliding and mounting the battery on your bike's bottom bracket could prevent proper installation of our motors.
We currently offer the BBS02 750W motors in one bottom bracket size for 68-73mm wide bottom brackets with an inside diameter of ~33.6-34mm.
We currently offer the BBSHD 1000W motors in three bottom bracket sizes:
- 68-73mm wide bottom brackets with an inside diameter of ~33.5-35mm.
- 74-100mm wide bottom brackets with an inside diameter of ~33.5-35mm.
- 101-120mm wide bottom brackets with an inside diameter of ~33.5-35mm.
❗️Check for chainstay obstructions to make sure and order the correct size motor for your bike's frame and bottom bracket ❗️
Our motors fit bikes with standard JIS-BSA bottom bracket (also known as standard threaded, sealed cartridge, square tapered, English or British).
If your bike has a Press Fit bottom bracket, then you will need an adapter to reduce the size of the bottom bracket inner diameter to ~34mm to make it compatible with these motors.
After searching online and measuring your bike's bottom bracket, if you are still unsure of whether our motor kits will fit with your bike, please email us the year, make and model of your bike at [email protected] for us to take a look. Please note, we only have access to the information that we can find online, we don't have the benefit of having your specific bike right in front of us! 🚵🏽