Electric Bikes - Auto assist isn't working

Hey guys, I recently transferred my PL350 to a new bike and now the auto-assist isn't working. The only thing I can think of is that I was using the motor with the wrong wheel size setting (20" vs. 700mm) and that messed something up, but I only rode it like this for about 5 min while I was testing out the new setup. Everything else seems to work normally--throttle, generative braking, etc.

When I put it into diagnostic mode (3772) the assistance values show 00 for all levels (1 - 4) while the generative values show 05, 10, 20, and 40. Also under these, a few other numbers/letters cycle through: 0033.7 (BAT appears right above the 7), Err, 25, and 1 47.

Is this as simple as turning on/off a control for auto assistance? Thanks.

Sounds like the axle hasn't been properly oriented. There's a mark on the axle which must point directly downward. The way auto-assist works on the Bionx systems is a strain gauge on the axle inside the hub. When you pedal, this produces a tensile force on the chain, which distorts the axle, which is picked up by the strain gauge and the Bionx controller and converted into a signal to the motor. Now, a complication is bumps and other road defects. These also stress the axle, though usually only in a direction perpendicular to the axis formed by the axle and chain. Hence, it's very important to install the Bionx with the axle properly oriented. The direction of the dropouts are key here. Did the dropout orientation change between your 2 bikes? I'm guessing they did, and that they're 90 degrees different.

You need a special tool to rotate to the axle in relation to the hub and dropout key. Check the Bionx instructions for details.

Then again, I could be all washed-up and you already know all this, and you properly oriented the axle already. In this case, I suspect the hookup to the strain gauge somehow got disconnected.

Thanks, you're right! I just checked the notch on the axle and it's in the 3 o'clock position.