Bafang M620 "Ultra" Mid-Drive
The torque-sensing monster behind most fat-tire moto builds. 160 Nm, a real torque sensor, and a fully integrated frame mount — this is the factory-grade Bafang.
Unlike the bolt-on BBS series, the M620 (Ultra) is a frame-integrated motor designed into purpose-built frames from Frey, Biktrix, and Bakcou. It uses a torque sensor for natural, proportional assist and pushes serious power, which is why it dominates the aggressive fat-tire and hunting-bike segment.
You don't retrofit an Ultra onto a normal bike — you buy a frame built for it, or a complete bike, and the part itself is usually a warranty/replacement purchase. Programming via the Bafang Config tool unlocks its real personality, from mellow torque-sensor commuting to full-send off-road.
Where to buy
Two paths — match your spend to the build. Quality picks last longer and come with real support; affordable picks get you rolling for less. Always confirm fitment, voltage, and connectors for your bike first.
Quality picks
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Pro tips from our test team
- Only fits Ultra-specific frames — confirm your frame before ordering a replacement.
- The torque sensor makes it feel far more natural than the cadence-based BBS motors.
- Pair with the Bafang Config tool to set sensible amp and speed limits for longevity.