I'm looking to convert my Cannondale T1 from a 10 speed 13-32 Ultegra setup to a 9 speed 12-36 setup. I can get a good deal on a Shimano XT 10 Speed Shadow rear derailleur. I use friction bar end shifters so indexing isn't an issue and I'm already using a 9 speed trekking crank up front.

Will there be any issues with using a 9 speed chain with the 10 speed derailleur? I'm presently using a 10 speed chain with the present drivetrain with no issues. Al

It will probably work but why not just stick with the 10-speed chain? It will certainly work with the 9-speed cassette. BTW, is your rear shifting friction? If so, the 10-speed MTB derailleur will work. If it's indexed, it won't.

You might need to shim the jockey wheels so the chain clears the cage.

I'd be surprised, though

I just had to spend time researching compatibility on Campy deraillieurs. The width of the jockey wheels on all models (9 -11) was 8.4 mm. The difference in chain width between 9 and 10 speed is because the pins don't extend beyond the edge of the side plate on a ten speed. Space between the plates should be the same and Campy rear derailleur won't know the difference. YMMV with Shimano. Your cogs may because you don't have the projections for the cogs to pick up the chain and you could loose a little precision that would be needed with indexed. Friction - just overshift a little more.

Don't know from experience but my guess is the worst that will happen is some slight loss of shifting precision. Front would be a different kettle of fish. Teeth on 10 spd chainwheel may be off center, bevels on teeth may be different, chain MIGHT actually ride on top of teeth dropping down to smaller chain wheel.

Thanks all. Al

It depends on the outside width of the chain. I used to run Sram PC-89r 9s chains on my Chorus 10s system and never had an issue other than that I finally ran out of those chains.

The most likely issue of running a 9s chain on a 10s group is clearing the inside of the outer sprocket when using the inner with the outer few rear sprockets. Even a 10s chain often touches the outer in the 39/11 combination, but many riders report issues with the 2md or even the third when the chain is a a bit wide.

So if I just move to the Deore MTB (M571) crankset for now, will I need to change out anything? Will the front derailleur handle the 22t (super) granny ring? I think that's my best move to begin - $89 for the crankset. Since it's a triple, no need to change anything else - I think.

Then I could get the new cassette and chain - and I think at that time, at least the rear shifter will need to be changed to a 9/10sp (dependent on cassette), right? Since the shifters are indexed, you have to run a shifter with the same indexes as gears in the cassette.

Done this way, I could get the initial benefit of the lower gearing, plus upgrade the crank. The rest of the 'benefits' are endlessly debatable but I could do that following the crankset.

So here is what I did. I picked up a used Deore 9 spd RD at my LBS plus a SRM 9 spd chain. I've got a Shimano 12-36 casstte on order. I may swap out the 12 tooth for my 13 tooth for a gear inch range 103.5 / 95.5 to 18 inches. More than enough touring range for this lad. Al

Just thought that I would give a final update on the project. The new bits for the project were a used Deore 9 spd RD, A Sram 951 chain and a Shimano CS-HG-61 12-39T cassette. The cassette comes as a solid block except for the 12t cog. I swapped out the 12t for a 13t cog. And that married to my Sugino XD-2 46-36-24 trekking crankset gives me 95.5 GIs at the top end and a stump pulling 18GIs at the bottom.

The SRAM 951 chain is 114 links long and was just long enough to get the job done. There is still a nice "S" bend in the chain when cross chained big ring to big cog but I wouldn't have been able to do it without adding some links if the big chain ring was any bigger. While I wouldn't normally use the big big combination, I think it important to set up the drivetrain to handle all available combinations. I've been known to make the occasional mistake.

I friction shift my touring bike. I went that route in order eliminate any compatibilty issues as I swapped out the sport touring drivetrain on my T1. The previous 10 spd cassette shifted quite well but could be very finicky when trying to lock into a gear. 10 spds really like to shift. The 9 spd seems to be a little more forgiving. Only time will tell.

That's it for now unless I decide to make the bike into a touring 2X9. Al

Words to live by for all mechanics and riders. This sentence should be made a sticky!!

FWIW I've used an 8 speed chain with a DA 7800 rear derailer (10 speed unit.) No issues.