Blaireau

I have a 10 speed crankset: I am told that it works with an otherwise complete 9-speed groupset....
What other combos work?

ptle

For the crankset it does not matter if you put a ten speed on a nine speed. It may not work if you do the opposite.

For the rear, I think it depends on shifter. I'm pretty sure you could run a "nine speed derailleur" with a ten speed shifter and have it work fine (assuming you swapped to a ten speed cassette/chain).

Ten speed chain should be able to work with a nine speed cassette, but not the opposite.

Blaireau

^^^

Thanks!

Caad 8

I have a 9spd bike. My crank is 10 spd, so is my chain. Everything else is 9 spd.

ericm979

Yes, I am running "9 speed" rear derailleurs on both my 10sp bikes.

mike868y

"9 speed" front derailleurs will work on 10 speeds as well.

Blaireau

All good to know. Hard to get an answer other than "you need to buy the whole 10 speed groupeset" from the lbs -- I wonder why....

ls01

This is so so true, the derailure needs to match the chain you are running. There is a width difference that causes excesive trimming with a ten speed f derailure and 9 speed chain. and the other way doesnt shift as well in my opinion. You can get it to work but not really right. I tried the 9 speed derailure on the 10 speed set up and I was allways fighting one position or the other no matter how I set it up.

I have been told not to use a 10 speed chain on a 9 speed crank as the narrower chain can get wedged in between the rings on a bad shift. I dont know if its true or not, havent tried it.

nkapinos

9 spd crank on 10spd setup doesnt work well either. I had this setup last summer, and the chain would fall in between rings when shifting FD if the RD was on the bottom 5 cogs (12,13,14,15,17)

bigd

A 10 spd crank on a 9 spd drive train didn't work well for me. I had intermittent problems with the chain jumping off the big ring while shifting up.

Drew Eckhardt 

When running a "10 speed" crankset (FSA carbon pro compact 50-34) with the stock spacing and an otherwise 9 speed Campagnolo drive train my chain rubbed on the big ring in the last three cogs leaving no overlap between rings.

I had to space it back to 9 speed dimensions to eliminate that (both Wheels Manufacturing and Latour make thin .6mm spacers for this purpose).

CyciumX

There is alternative cable routing : https://www.sheldonbrown.com/derailer-adjustment.html

Scroll towards the bottom and have a look-sie