105 11-speed chainset compatible with 8-speed?

craigus89

I will eventually upgrade my winter bike to full 105 5800 when I have the money available, I'm pretty sure my BB is on it's way out and my chainset is a bit worn and only a cheapo FSA job, rather than replace like for like (BB is a FSA square taper 68 x 110 sealed cartridge) I'm wondering if I should get a 105 chainset and compatible hollowtech BB, but...

Question is, will an 11-speed Shimano 105 chainset work with an 8-speed Claris groupset? If not, why? I'm assuming that the distance between the rings could be smaller or larger? Couldn't seem to find from a search.

I don't really want to commit to spending out on the full groupset at the moment, as my hubs also either need servicing or the wheels replacing, so groupset plus wheels and tyres I'm getting into new bike territory....

paul_the_pedaller

I was searching for info on this recently and found this in my history:

"Chains for 11-speed systems are around 5.4mm wide on the outside, vs. around 5.9mm wide for 10-speed ones, so that’s 0.25mm narrower from the center of the cog tooth to the end of the chain pin on each side. That’s not enough to likely even be noticeable in any difference in how it passes through the jockey wheel cage. It will be slightly slower getting over to the next cog or chainring during a shift, but the difference in width is so small that it’s also likely not to be noticeable. If you were to run an 11-speed chain on a 9-speed or 8-speed system, however, you would likely start noticing some decreases in shifting performance.


Full article here: Tech FAQ: Chain width explained, compatibility queries answered

craigus89

Thanks for the link. That is mainly talking about actual chains though, I'd still be running an 8-speed chain, it's just whether that would work with an 11-speed chainset/crankset

The Rookie

It's POSSIBLE than the chain will foul the larger gear when on the smaller one as the rings will be closer together to allow for the narrower 11 speed chain, as a 9 speed chain will work perfectly on an 8 speed cassette that may steal back just enough if there is an issue.

drlodge

It should work OK, would match it with a 9 speed chain though.

I've got an Ultegra 11 speed chainset on the Condor, with an old Uniglide 7 speed freehub/cassette on the rear and pair this with a 9 speed chain. Works fine.