Bafang BBS02B Installation Guide

Tools Required

Step 1: Remove Existing Drivetrain

Remove cranks with the crank puller. Remove BB using your existing BB tool. Clean the BB shell thoroughly — any grit here will cause creaking later.

Step 2: Install the Motor

Thread the motor into the BB shell from the drive side. Hand-tighten first, then use the CNC lockring tool to torque to 30Nm on the non-drive side retaining ring. The motor should not move at all when fully torqued.

Step 3: Install the Chainring

Mount the supplied chainring on the motor output shaft. Use the M5 bolts with Loctite 243 (blue). Torque to 8Nm. Check chainline to your smallest rear cog — it should be within 3mm.

Step 4: Reinstall Cranks

Install the supplied crank arms. Torque pinch bolts to 14Nm. Reinstall pedals — left pedal is reverse thread.

Step 5: Mount the Controller

The controller tucks behind the BB shell. Route it so the cables point upward. Use the included frame protection foam strip under the mounting plate.

Step 6: Route Cables

Route the motor cable along the downtube (inside if possible). Use zip ties every 8–10cm. Run the display cable up to the handlebar. Keep all cables away from the front wheel and brakes.

Step 7: Install PAS Sensor

Mount the 5-magnet disc on the crank spider with the 4 screws. Mount the sensor on the chainstay — 2–4mm gap to the magnets. Connect to the main harness.

Step 8: Mount Display

Clamp display to handlebar. Connect 5-pin connector to harness. Cable should have no tension when bars are turned full lock in both directions.

Step 9: Test & Program

Power on — you should see the Bafang boot screen. Set wheel circumference (2096mm for 29", 1995mm for 27.5", 1887mm for 26"). Set max current, PAS levels, and speed limit to match your local regulations. Test at PAS 1 at walking speed before riding.

Torque Reference

Common Mistakes