Ultegra 6700

No rear derailleur is crank-specific.

The type of RD to use depends mostly on the casette but strictly speaking it depends on how big the total gear range is; a characteristc which is quanitfied by the required "teeth capacity".

What do you mean by "SS rear derailleur"?

When I look up ultegra rear derailleur on the chainreaction website it list 2 ,an RD and a SS ???

Sorry that should read GS and SS -GS is a medium derailleur and the SS is short cage ,just not sure what one I need.

Hi monkeyman1, what size rear cassette are you using?

Hey KLabs, I have new in the box 11-28 ultegra 10 speed was just wonder'n if the short cage will work cause i can get one for a very good price.Thanks.

Okay so it is a short cage. From memory the short cage derailleur has a capacity of 30 (look it up with shimano techdocs). Your required capacity can be calculated by taking the difference between the two chainrings and the difference between the largest and smallest sprocket and summing these differences together.

As an example of this with a 53/39 crank and 11-28 cassette the capacity is

capacity = (28-11)+(53-39) = 31.

which would be techically too high for the short cage derailleur. With a 25-11 cassette it would be 28 which would probably be okay.

Hi monkeyman1, the following is your guide

Required Capacity with a Standard Crankset (52-39) = (11-28) + (52-39) = 17 + 13 = 30T or with a 53-39 Crankset (refer tafi's post) = 31T
Required Capacity with a Compact Crankset (50-34) = (11-28) + (50-34) = 17 + 16 = 33T

Total Capacity of an RD 6700 = 33T (RD-6700-SS) 39T (RD-6700-GS)

So according to the Shimano Specs the answer is YES, you can use a RD 6700-SS with a Standard or Compact Crankset :-)

PS: People have successfully used setups that have exceeded the 33T RD Total Capacity by 1 or 2T, but success depends on a few factors such as the type of Derailleur Hanger(DH) :-)

Hey everyone,thanks this site has such good info !

Quoted post said:

Originally Posted by monkeyman1 [IMG]/img/forum/go_quote.gif[/IMG]

Hey, will a 6700 ultegra ss rear derailleur work with a standard crank 53-39 or do i need a compact 50-34 crank,thanks.

I have friends who don't want to use anything bigger than a 21 cog on the rear, they're mad as batshart. Small gears are the future.