hi, im putting together an sworks transition and ive got 9 speed bar end shifters so i bought a 9 speed 12 x 25 ultegra hg cassette and an ultegra double crank. Can i use dura ace or ultegra derailuers? whats short cage vs long cage? what chain do i buy (seems like there are 80 billion different ones all with different numbers)? THANKS!
You could use either the Dura Ace or the Ultegra rear derailleur, even an 8- or 10-speed variety. It's the shifter that controls how far the derailleur moves for each "click".
You could use either a short- or long cage rear derailleur (the long-cage is made for very wide-range gearing with triple front chainrings.
As Brider says, any Ultegra or DA deraileur should work. I like short cage; the shifts seems crisper.
For chains, I like the SRAM ones. They're more durable IME and the powerlink makes them real serviceable for cleaning. Just be sure to get 9 speed if you have a 9 speed cassette (PC-x91 would be the model number; the 991 is the top line)