Ultegra Long Cage vs Medium Cage vs Short Cage

Canyonaero

Hi all,
I apologise in advance as I'm sure this subject has been discussed here before but a quick search didnt answer my question.

I will be replacing the Rear Derailleur on my road bike for next season but im being faced with different cage length options.How do i know which derailleur I am already running on?

My road bike is a canyon 8.0 CF 2011 model which is still running the Ultegra 6700 setup it came with which is a standard ultegra 12/25 cassette and 53 /39 chainrings.

Cheers

C.

Lumen

I think there is only one type of 6700 Ultegra RD, only the finish is different.

Model Number RD-6700-SS
Maximum Sprocket 28T
Minimum Sprocket 11T
Maximum Front Difference 16T
Total Capacity 33T

http://www.shimano.com/publish/content/global_cycle/en/us/index/products/road/ultegra_6700/product.-code-RD-6700-SS.-type-..html

This should be fine.

Kav0777

What does the "total Capacity 33T" refer to?

Morgan

Kav0777 wrote: »

What does the "total Capacity 33T" refer to?

It's the amount of chain-slack the derailleur can take up. That's the difference between the smallest and largest sprockets on the back and the smallest and largest chainrings on the front.

In the OPs case thats:
(25-12) + (53-39) = 27

The longer the derailleur cage, the greater the capacity.

seamus

The capacity is the maximum difference between your biggest rings (front and back) and your smallest rings.

That is, the minimum amount of chain you will needs is enough chain to cover the smallest ring at the front and the smallest cog at the back.

The maximum length of chain you need is enough to cover the biggest ring at the front and the biggest ring at the back.

The rear derailleur takes up the slack when changing from the maximum through to the minimum.

So the maximum capacity of the derailleur decides the biggest difference you can have between this minimum & maximum.

For example, if you're running a fairly standard setup = 12 - 27 on the back and 34/50 compact on the front, then the minimum gear is (12 + 34) = 46 and the maximum gear is (50+27) = 77. The difference between these is 31, which means the rear deraileur must have a max. capacity of at least 31T.

In general you should use a derailleur which is as close as possible to the capacity you require (i.e the shortest mech you can). The longer the derailleur, the more flex is introduced and the less reliable the shifting. Longer mechs are obviously also slightly heavier.

moggs1972

i have the same bike but with 11-28 on the rear, the original rear mech is a short cage so replace with same

Canyonaero

Thanks for the help guys, short cage it is.....