Changing Ultegra Cassettes

[RobRollin]

If I wanted to change from a 9sp Ultegra to a 10sp Ultegra cassettes do I have to change my shifters and rear/front derraliur as well?

[rustychisel]

Shifters (STI units) and maybe rear derailleur to get best shifting, definitely. Chain, certainly, and perhaps front derailleur.

$$$$$$$$$$$$$

[RobRollin]

...............might as well look at a new groupset.

[rustguard]

This is second hand so don't quote me. I recently wanted a new front dérailleur for my 9sp a guy in a shop looked it up and said the 10sp ultegra is slightly narrower than the current 9sp, which was tiagra maybe, I can't remember. As to the rear it would be advised to change it for a 10sp. theres not much in it though. Out of curiosity has anyone ever tried a 9sp rear dérailleur with 10sp?
obviously any shifters that have indexing would be no good.

[LuckyPierre]

You can't get 10-speed shifting from 9-speed shifters, so that means new ones.
I'd use 9-speed Ultegra in preference to 10-speed anyday, so I'm the last person to ask - but why change? Get a new 9-speed cassette if you need one, a CN7701 chain and away you go!
You can use 10-speed front and rear derailleurs with 9-speed chains / cassettes - the Shimano website has a compatability chart somewhere - but that's what I run on the girlie bike. Tojo is all 9-speed Ultegra.
I think that the 10-speed cassette is actually slightly narrower than the 9-speed, so the 9-speed rear derailleur probably has enought throw to work.

[RobRollin]

Thanks for the help!!

I'm looking at staying with Ultegra 9 speed and changing my rear cassette to 12-25 for better climbing.