Campagnolo Eurus with Shimano 10S 11-28 won't stay in the 11 cog
 

Per the title, I have a set of Campy Eurus that worked fine with a Dura Ace 12-23 but when I installed an Ultegra 11-28 and then even a 105 11-25 it hops when attempting to engage the 11cog. Doesn't matter large or small front ring. All the other gears work fine. Is there anything special shim wise that I need to look at?

The bike is a 2002 Trek 5200 USPS with recent Ultegra 6700.

Thanks,

miatastuff

11 to 1 you used the wrong lock ring.

Campy cassettes don't come with lockrings, which are normally supplied with wheels and hubs. However Campy cassettes starting with 11 which are supplied with their own special smaller OD lockrings.

Reason being, that the lip of the larger standard lockring comes out too far and interferes with chain engagement on an 11t cog.

Even though you're using a Shimano cassette there's still the issue of the lockring diameter being too large for an 11t cog.

Thanks FB! I think you got it. I found the Eurus owners guide. It lists a Campy CS-801 lockring for 11T Shimano. That may be the ticket!