Bicycle Mechanics - Do all RD's work with all shifters? How do i tell?

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grasscutter
10-03-09, 08:46 PM
1986 Trek 560 Pro. Been doing some upgrades over this year. Installed Shimano 7sp Brifters, and now want to upgrade my RD (has original suntour). There are lots of RD's out there. Long cage, short cage, and many many different Brands.

What will work with my set-up? Any RD's that won't work? My preference would be to find an older Dura Ace or Ultegra.

I appreciate the advice.

operator
10-03-09, 08:51 PM
Shimano will work fine with no doodads. You can get campy rd's to work with a pulley gizmo called a shiftmate (don't do this if you don't need to). Sram derailleurs will also not work.

P.S 7 speed isn't much of an upgrade. We're up to 10 now, 11 for campy (queue joke).
joejack951
10-03-09, 09:22 PM
So long as you don't buy a Dura Ace 8-speed era rear derailler, any Shimano RD should work for you. Long/medium/short cage is dependent on your gearing (how much chain wrap you need). Typically, road doubles use short cage, road triples use medium cage, and MTB triples use long cage.

Scrodzilla
10-03-09, 09:27 PM
What about a 1x7 setup (14-28)? Which cage RD would be optimal?
joejack951
10-03-09, 09:31 PM
Well, it would depend on your cassette choice. If using a road cassette, a short cage RD could easily handle the chain wrap. If using a wide range MTB cassette, there is a medium cage MTB RD option which has less chain wrap capacity than the MTB long cage RD but can handle 34 tooth cogs. Sometimes you can get away with a road derailler and a 32-34 tooth cog, but if you wanted something that would definitely work, the MTB medium cage would be the ticket.
Steev
10-04-09, 06:31 AM
What about a 1x7 setup (14-28)? Which cage RD would be optimal?

The only limitation you have in this application is that "road" derailleurs are spec'ed for no bigger than 28 tooth rear cogs. Some people have pushed this limit by a couple of teeth sucessfully. Personally, I would use a short cage but that's just a aesthetic thing.
Jeff Wills
10-04-09, 04:27 PM
What about a 1x7 setup (14-28)? Which cage RD would be optimal?

Short cage.

FWIW: I just finished a 1x7 conversion, but since it's got a 12-19 cassette it's not pushing the limits of anything.
mzeffex
10-04-09, 04:33 PM
Make sure to check the requirements of rear derailleurs. Some, such as 105, have a max tooth of 27. Trust me, I have learned from experience, it matters.
Al1943
10-04-09, 04:36 PM
What Joejack951 said. You need a Shimano derailleur but NOT a pre-9-speed Dura-Ace.