Compact Chainsets

Meds1962

Can anyone advise whether a 10 speed chainset can be used to replace a 9 speed one. Specifically what I've got in mind is to replace my 9 sp standard shimano 105 chainset with a compact, but as far as I can see I would have to down grade to Tiagra to get a shimano 9 speed compact.

alfablue

I am not absolutely sure, but the chain for 10 speed is narrower than 9 speed I believe, so I don't think you can run a 9 speed chain on a 10 speed cassette, but I think you should be able to run a 9 speed chain on a 10 speed chainset (the width of the chain not being an issue). This compatability chart may or may not shed some light on it, though I think the crucial compatability issue is chain and cassette.

I am running an Ultegra c/s on a 7 speed chain/cassette no prob.

Hopefully someone with more certainty will be along soon!

maddog 2

it'll be fine.

SDP

yes but you can run a 10spd chain on a 9spd cassette :roll:
chainsets ..no problem at all

andy_wrx

9sp chain on 10sp chainset (or vv for that matter) : fine !

Meds1962

That's interesting, I'd already looked at the shimano compatability sheet which is why I reckoned the Tiagra was the only compatible one. I've noticed some internet sellers saying the 10 speed chainset is compatible with 7, 8 and 9 speed but was wary as this is at odds with what shimano say.

Presumably the difference in thickness between the plate that 9sp and 10sp chainrings are made out of is negligible, or the inside dimensions of 9 and 10sp chains is near enough the same??

maddog 2

inside dimensions are all the same

only the external width is narrower

7,8,9 and 10 speed will all run on the same ring