California Ebike is proud to announce the Bafang “100 mm” BBS-02 Mid Drive for installation on Fatbikes. This product was designed and manufactured in the USA and is in stock and available for sale immediately.

Please refer to the Bafang Fatbike Conversion product page for price and availability.

California Ebike Bafang Fatbike MongooseThis Bafang “100 mm” Mid Drive consists of a modified Bafang BBS-02 drive with an extended axle to accommodate installation on a bike with a 100mm bottom bracket. Modification of the Bafang drive to use the extended axle is completed by California Ebike and shipped as a sealed and whole unit in a kit. The kit includes the same list of parts as the standard Bafang Mid Drive BBS-02 conversion kit we sell.

100mm Extended Axle

They key component of this modification is the 100 mm extended axle which is made from heat-treated alloy steel. The axle is CNC machined with four precision ground bearing journals and a spline that must be cut using a wire EDM (Electrical Discharge Machining) process. There are a limited number of shops in the country that can perform this type of machining and it meets or exceeds the strength and durability of the stock axle.


A secondary design challenge with the 100 mm extended axle is mounting the included tube extension to cover the additional length of axle. For strength and precision of alignment, the existing Bafang botom-bracket tube is CNC thread milled to ensure positive alignment integrity.

Modified Bafang Mid Drive for 100 mm Botom Bracket

This image contains a modified Bafang drive to accommodate the extended axle. On the far left is the standard stock axle that comes with the drive. In the middle is the extended axle designed and engineered by Doug Snyder.

bafang fatbike extended axle kit

Installing the Bafang “100 mm” Mid Drive

The combination of these parts and modifications allows you to install the Bafang Mid Drive onto your Fatbike the same way a standard Bafang Mid Drive conversion kit is installed. If you are interested in purchasing the Bafang Fatbike Mid Drive conversion kit, please act soon as there are a limited number of extended axles in our initial manufacturing run.

California Ebike Bafang Fatbike Mid Drive Kit

Current California Ebike Customers

Bafang BBS-02 Fatbike InstalledIf you have purchased a Bafang Mid Drive in the past and would like it converted to the 100 mm axle, contact Doug directly at Please contact us as soon as possible so that we can include your order with the next production run of the CNC thread milling.

International Customers Outside the U.S.

To our international customers that have contacted us about this conversion, we are working on a solution that will not require you to send us your Bafang Mid Drive and wait while California Ebike completes the modifications. Please stay tuned and we will be in touch with those who have contacted us already.

Thank You