Bicycle Mechanics - What rear Derailleur

I have a 9 speep Giant with Ultegra long cage rear Derailleur with Dura Ace shifers. This is a compact double 50x36 chain rings, I want to put a short cage Dura Ace rear Derailleur on the bike. Which one would be compatable 6500 6600???

The 6500 was the 9-speed era rear derailleur. However, what do you hope to improve with the change?

The clicks are in the lever not the RD, just get a similar one as that works now in the shorter cage.

My question: why bother?

so ditto
what do you hope to improve with the change?
Aesthetics?

more importantly, what are you running for a casette? You sound knowledgeable so I assume you know what you are doing but obviously if you have a big casette on the back you will need the long cage. Otherwise, RD's are quite flexible, the whole 8spd/9spd/10/spd designation on deraileurs has never made any difference in my drivetrains.

Yes, any of the Shimano 9 speed derailleurs will work with you 9 speed shifters.

All Shimano indexed rear derailleurs, except old Dura Ace (pre-8-speed) and new Dyna-Sys (MTB 10-speed), utilize the same cable-pull ratio, so it doesn't matter if it says 8-, 9-, or 10-speed.

Any short cage (SS) Dura-Ace RD (9-speed and up) will work for you, assuming you're not exceeding the wrap capacity or max cog rating. The fact that there was a long-cage (GS) Ultegra, I'd check to make sure you won't exceed the wrap capacity of the RD.

Chain wrap required (in Teeth) = [outer chainring + largest cog] - [inner chainring + smallest cog]

You can look up the wrap capacity of the RD you want on Shimano's site. If your crank/cassette combo exceeds the SS RD's chain wrap capacity, go with the GS.

Your cassette might be too much for a short cage to handle. What cassette do you have? Which leads into:


what do you hope to improve with the change?

My cassette is a 12-25 or 12-26.

All Shimano indexed rear derailleurs, except old Dura Ace (pre-8-speed) and new Dyna-Sys (MTB 10-speed), utilize the same cable-pull ratio, so it doesn't matter if it says 8-, 9-, or 10-speed.

Any short cage (SS) Dura-Ace RD (8-speed and up) will work for you, assuming you're not exceeding the wrap capacity or max cog rating. The fact that there was a long-cage (GS) Ultegra, I'd check to make sure you won't exceed the wrap capacity of the RD.

Not quite. It's the pre 9-speed Dura-Ace rear derailleurs that are not compatible.

Both of those with work with 26T rear.

6500 and 6600 are Ultegra. 7700 is DuraAce 9 speed.

Not quite. It's the pre 9-speed Dura-Ace rear derailleurs that are not compatible.

Oops, thanks. I'll edit my post.

It is not worth the trouble I am going to part out the bicycle.

well yeah, you could put a ss RD on there but your gs ultegra should work perfectly fine.