Dynamo Wheel

thingiverse

I've never seen this crucial connection between the bike wheel and the dynamo's central axis wear out, but the fact is that it could happen. This part doesn't seem to be sold as a spare anywhere. The modified version of "Replacement Gear" created by Patoch makes printing easy and even adds extra reinforcement blocks for added strength. However, it's worth noting that the inner diameter of this gear is only just shy of 5mm.