Looking for a little bit of technical assistance please.
The time has come to replace (at least one of) my chain rings. Currently, the bike is Ultegra (6700) with the exception of the chain set, which is an FSA SL-K Light. Ideally I want to swap the chain set out for11 speed Ultegra 6800 (would like to get a Stages crank arm at some point and want to continue to run 52 36 chain rings) but I could do with a bit of guidance re the 10 / 11 speed compatibility.
Now, I appreciate that Shimano say you cannot run the 11 speed chain set with the rest of a 10 speed group but, other than for sales reasons, I'm struggling to find logic for this:

- 10 and 11 speed chains are the same roller width
- the spacing between the chain rings is the same

The 11 speed chain is ~0.26mm narrower (has thinner side plates to enable it to retain the same roller width), but don't see why this would matter given the above

I would have thought that these were the only real considerations, but would be really grateful if somebody would confirm / correct. Have read that the teeth on the 6800 chain set are optimised to run with an 11 speed chain; just marketing b/s?

First hand experience of running a combination of Shimano 10 and 11 speed would be much appreciated (as would an informed opinion!).


srchar [268 posts] 2 years ago

You can run your 11 speed cranks with a 10 speed rear, but you'll need to spend another £20 on an 11 speed chain.

centurion48 [13 posts] 2 years ago

Lennard Zinn has addressed similar issues several times over at Velonews Technical FAQ:

Read that segment and also the linked one. Should put your mind at rest.