10 spd ultegra rd compability with 9 spd ultegra cassette

[Author]

I have 9 spd grouppo and i was wondering if I could use 10 spd rear d instead of regular 9 spd? I have to replace my old rd anyway because i crashed with my bike and rd was bent.

[boudreaux]

I have 9 spd grouppo and i was wondering if I could use 10 spd rear d instead of regular 9 spd? I have to replace my old rd anyway because i crashed with my bike and rd was bent.not a problem