What are these?

I just got a new Koxx One Green Spirit and put it together. It came with these 2 cylindrical pieces that seem to fit in the cranks where they attach to the hub. It looks like I’ll need a special tool to screw them in and get them out again. Can someone explain what they are?


they may have just been spacers for the cranks but not sure

They’re self-extracting rings for the cranks.
They enable you to remove your cranks without using a crank puller.

You can read about them here.

They are crank self-extraction inserts. You can screw them in with a pin spanner:

Once they’re screwed in, the cranks will automagically come off when you loosen the main crank bolt.

They don’t tend to work very well long-term, because if you screw them in they take a lot of abuse, and if you don’t put them in the threads they’re supposed to go in take a lot of abuse.

They are to assist in removal of the cranks.
You screw them into the cranks and when you need to remove them you just undo the crankbolts against the little extractors. The bolts will then force the cranks off of the splines. Very simple but extremely useful!

Got it. Thanks.

I’ll just leave them off then since I don’t have a pin spanner. If I need to change the cranks, I’ll use a crank puller.

You don’t need a pin spanner.

Unfortunately, this design usually is implemented so that the threads are left-handed, so a normal crank puller won’t work.

I’m glad you mentioned that. You probably saved me some confusion and a trip to the bike shop.
It makes sense. You don’t want the inserts to unscrew with the crank bolts.