you have to change, chain, shifters, casette rear derailer......

you could do with 9 speed rear derailler and shifters on friction mode,....not index...

but still need the 10 speed chain and casette....front 10 derailer is also nicer with 10 speed but it s possible to do with a 9 speed

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Jonathan Caron / Professional Coach / ironman champions / age group world champions
Jonnyo Coaching
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As long as the derailleur ratio is the same (which it is) you can keep the rear derailleur also. It will work fine in indexed mode. The only exceptions to this are some earlier Dura Ace stuff that had different derailleur ratios. See Sheldon Brown's site for more info.
http://www.sheldonbrown.com/dura-ace.html

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Kendall Frederick

Orange Park, FL

how will you make a 9 speed derailler shift for 10 speed on index ???? that dosnt make sence??? unless you only use it for 9 speed cassette???? but that isnt what the OP is asking.....he wants 10 speed....

maybe i m wrong????

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Jonathan Caron / Professional Coach / ironman champions / age group world champions
Jonnyo Coaching
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Change the cassette and shifter. You may need to change the chain also, but I'm running a 10speed chain on 9speed with no problems, but It's good practice to change the chain when you change the cassette.

Rear mechs should work fine. Front mech definatly fine.

Why change to 10 anyway? Do you really need that extra bailout sprocket? I have 9 on all my bikes and can see no reason to go to 10.

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"Here's how you run a marathon. Step 1: You start running. Step 2: There is no step 2." - Barney (How I Met Your Mother)

The derailleur is not speed specific, as stated above, unless the movement ratio changes from one generation to the next. This is why Shimano and Campy are a little different for the same number of speeds on the rear cluster.

When a shifter either gives or takes a certain amount of cable, the derailleur will move a specified distance in either direction. On a 9 speed, the cable moves a certain amount and the derailleur moves a certain amount. On a 10 speed, the cable moves a little less and the derailleur moves a little less, but directly proportional to the 9 speed setup. The Shimano RD is unchanged from 9sp to 10sp with respect to this cable movement.

so.... if i have a 10 speed sti shifter and use a 9 speed RD, on a 10 speed casette..... you tell me it will work?????

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Jonathan Caron / Professional Coach / ironman champions / age group world champions
Jonnyo Coaching
Instargram

[reply]so.... if i have a 10 speed sti shifter and use a 9 speed RD, on a 10 speed casette..... you tell me it will work?????[/reply]

Yes.

I'm looking for closer ratio's in the middle of the cassette. I thought that by going to a 10spd setup i coudl eliminate that big jump between gears that I always seem to hit without sacrificing the top or bottom gear.

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This is your life, and it's ending one minute at a time. - Fight Club
Industry Brat.

Dont forget the 10 speed chain, but yes.

Shifter, cassette, and chain is all that is required to make the switch