My bike has compact crank Rival 50/34 and I find that 50 is too high. I bought a used 46 chainring on auction site and it came with a plastic piece, but where does it go? Also there is one hole with some strange markings inside like something should go inside. It is different than the other holes because those are smooth.

I don't know what this piece is for. The numbers on the ruler are cm, smaller lines are 0.5mm.





Does something go in this bolt eye?

Have you asked the seller? you may get the answer there!

Yes obviously ask the seller, no comment on the rubber bush grommet, the other photo to me is too close up to understand, as you say it's on the chain ring ? take another photo not so close: maybe I'm missing the point.

The serrations in the ring bolt hole are artifacts from a female half of the ring bolt and nut which had serrations in it's outer surface to better grip the ring hole. More common on cranks that have the 5th hole positioned behind the crank arm, as it's hard to get a ring nut wrench in there.


The plastic bit looks a lot like a plug for some hole. At about 4mm in diameter (for the "shaft") I suspect it's meant to fit in a M% threaded hole. maybe a bottle cage boss. Anyway I doubt it's intended to be used on the ring, likely just was along for the ride in the packaging. Andy.

Ok - you are exactly right about the serrations in the bolt eye. From what I can find, my chainring has a nut pressed into the bolt eye because one of the bolt is hidden by the arm. Apparently it is common to Sram 22 speed systems. I had no noticed one bolt eye is hidden until now. I guess Sram tried to make it look like Shimano and FSA 4 bolt system.

The seller just buys stuff from sales like garage sales and then sells on auction site. She does not know the origin of the plastic plug.

If you are able to bolt the 46t chainring on correctly, I'd be very surprised if the rubber piece played a meaningful role in the chainring function.