bafang crank arm 170mm electric bicycle crank mid motor cranks essential parts mid motor accessary bbs01 bbs02 bbshd electric bikes part & accessories e bike crank leg bafang this is a replacement straight crankarm (no offset) that is the same as what is shipped with the bbs01 & bbs02 drive units. you must specify a side l or r when ordering. the right is the drive side and the left is the non-drive side. you must use the right side crankarm for the correct side of the bike<br><br>be aware when mounting pedals that the left side pedal is reverse threaded so you tighten it backwards (counterclockwise)..drive side is normal, clockwise to install it.