[MeSparks]

I'm planning to upgrade a Spec Roubaix triple to Ultegra derailleurs front/back.

Should I be using a long or short cage rear? Why would I select one versus the other?

Thanks

 

[PJ352]

I'm planning to upgrade a Spec Roubaix triple to Ultegra derailleurs front/back.

Should I be using a long or short cage rear? Why would I select one versus the other?

Thanks

If you're staying with the triple crankset and just changing f/r der. you'd stay with the OEM (long cage) RD.

FWIW, unless there's a reason to take the opportunity to upgrade, IMO it's not necessary, because you'll see no difference in performance with this change.

Short or long cage RD's are chosen based on total tooth capacity of the drivetrain.
Example: 5700-GS RD total capacity = 39T, 5700-SS RD = 33T

 

[chocy]

If you have triple you should use long cage. Long cage allows more slack in chain that is required for more gear range using triple.

 

[MeSparks]

If you're staying with the triple crankset and just changing f/r der. you'd stay with the OEM (long cage) RD.

FWIW, unless there's a reason to take the opportunity to upgrade, IMO it's not necessary, because you'll see no difference in performance with this change.

Short or long cage RD's are chosen based on total tooth capacity of the drivetrain.
Example: 5700-GS RD total capacity = 39T, 5700-SS RD = 33T

Its more about the positive locking adjustment screws than performance.

 

[PJ352]

Its more about the positive locking adjustment screws than performance.

YMMV, but I've used both 105 and Ultegra and never noticed any difference in set up/ performance. There are a number of reasons why you're experiencing problems (assuming you are) that are unrelated to the quality of the components. They may simply need cleaning/ relubing/ readjusting.

 

[wim]

Its more about the positive locking adjustment screws than performance.

Now you got my curiosity up: what are "positive locking adjustment screws" on a bicycle derailleur?

 

[Mr. Versatile]

Now you got my curiosity up: what are "positive locking adjustment screws" on a bicycle derailleur?

There are 2 screws on each derailleur that limit its side to side motion. on the rear der. the inside limit screw prevents the der. from shifting the chain into the spokes, assuming it's adjusted correctly. The outside limit screw prevents the der. from shifting the chain too far past the smallest cog where it can get caught between the frame & the small cog.

The front der. limit screws do the same thing. If you look closely at these 2 screws you'll see there's a little tab on the inside that the screw bumps against there fore preventing from going farther.

I have bikes with Shimano 105 & Dura Ace. They both work well. IME the 105 is a little clunkier than the Dura Ace. The Dura Ace is like butter. The Dura Ace brakes seem better too.