Had a quick google and the jury seems to be out on this, but the conflicting opinions seem to be hypothetical. Has anyone got actual experience of running a 9 speed rear mech with 10 speed cassette and chain (I know I’ll defo need 10 speed shifters).
thanks

Yes. It does NOT work. It never will (the exception being if you use these )- the pull ratio is different. I found when I ran an old Shimano XTR mech and new 10 speed shifters that it seems to miss some sprockets out regardless of what you do because the cable moves more than the mech needs to change gear.

cheers, thanks for reply

What he said though as I’ve got all the bits, I’m going to give it a go to see if something like the hubbub campag/shimano bodge can be made to work – eg alter the pull of the rear mech. Probably not but worth a go.

The only caveat is that (as he said) if you buy the road 10 speed flat bar shifters, that WILL work with a 9 speed rear mech.

Clubber- I tried that bodge in your picture. It didn’t work. Jump in cable pull ratio seems too big, it’s more like Shimano-Sram than Shimano-Campag.

Maybe but in theory it’s always possible to bodge it just maybe not with that method. It’s more whether the jumps between gears still work once you’ve got the cable pull right.