Rear derailleur question.

ben@31

Hi,

I'm having to buy a new rear derailleur. Would a new Ultegra SL 6600 be compatible with a Tiagra set up? The cassette is 9 speed 12-25 and the front chainrings are 50-34 compact?

Also would a short cage or medium cage suit me best?

Thanks for your help.

mister p

Yes it will work and a short cage will be fine.