ebike crank arms

[AW10]

I recently put a a Raleigh ebike together for a friend. It was shipped box and needed the pedals installed and the handlebars straightened and the seat raised. I struggled to install the pedals until it dawned on me that the left and right crank had been swapped at build time. So the pedal marked left with its left hand thread is fitted to the right side and vice versa. Unlike a conventional bike with the chainring spider on the right crank arm these crank arms look to be interchangeable. I thought no more of it until...

Today she rings me to tell me that the left pedal has managed to unscrew itself from the crank arm far enough that she's basically torn the threads out and the crank arm is toast. A bit of research suggests mechanical precession has unscrewed the pedal. Have now contacted the selling dealer to get them to replace the crank arm. Wish me luck!

[Cupramax]

I’ve found my Bafang kit unscrews the crank arms too, I now check them for tightness periodically, never actually had one come completely off before though.

[AW10]

Bless her cotton socks but she doesn't really have the mechanical sympathy/nous to notice something's wrong until it's good and broken!