Looking to update the gearing on my gravel bike. It’s currently running an 8 speed set up (Claris Mechs & Shifters / FSA Chainset). I’m looking at going to a 10 speed road set up. Question:

If I buy shifters / rear mech / chain / cassette (lets say 105 spec) will I get away with running the existing front mech and chainset?

I have read that 8 /10 seed chains have the same internal dimensions but want to be sure. Also will there be problems with the front mech? I’m guessing cable pull will remain the same as number of rings still the same, but what about cage width?

Will upgrade chainset / f mech if needed or in time, but looking to see what needs to be done to get up and running.

It should work, there could be spacing issues between the chainrings but I doubt it’ll matter much it hack terms. A whole new set up will make you feel all nice and warm inside though and 8/10 speed isnt going to make you any faster so why not save and wait?

Also if your going new 10 speed it’ll be Tiagra and front mech pull is different, if your going old 105 10 speed why bother Tiagra is better.

It will be fine. I ran an 8 speed sora front derailleur with 10 speed Ultegra for ages because I couldn’t be bothered to source the relevant mech. Same for chainrings.

Thanks both.

Wilburt – which version / year of Tiagra do I need to look for?

Was looking at light use second hand groupsets and I forsee compatibility issues with front mechs, hence the question on that side of things.

No need to change rear mech.

Just need shifters, cassette and chain.

But why bother? Seems a big faff and expense for 2 more gears that I would hardly notice.

You need to do the lot inc chainrings and mechs to take advantage of slightly slicker shifts from the better groupset,

That’s good point… I forgot to say I didn’t swap the 8 speed Sora rear derailleur either, just the shifters, chain and rear cassette (which has the same spacing).

I’ve swapped them back to eight speed now as the ultegra is required for a cross bike build.

If your buying used then older 105 10 speed is likely the best option, newer of all the levels 11 and 10 speed has a different pull ratio so wont work.
As pointed out though 8 speed is a good standard IMO, very reliable so ideal for CX.