Shimano Ultegra CS-6600 12-27T Cassette

Triathlon Forum
1

Would like to replace my Shimano 11-23T (Ultegra group) with this one. Anyone had any success or issues? Would like to prevent from having to update the RD.

2

What ultegra group do you currently have on there? As long as both are the same number of gears, you should be fine. Probably want a new chain tbough

3

Would like to replace my Shimano 11-23T (Ultegra group) with this one. Anyone had any success or issues? Would like to prevent from having to update the RD.

You’ll be fine. The 6600 series short cage derailleurs can handle up to a 27t cog (I’m assuming this is what you have). You will likely have to readjust the derailleur; namely open up the B-gap. But other than that, you’re smooth sailing.

Also, regarding the chain length issue, there is a chance you’ll need a longer chain, as the difference between big cog and small cog size is larger on the 12-27. But that’s only if the chain was sized improperly to begin with (i.e. too short). We just published a 2-part series detailing this: http://www.slowtwitch.com/...o_-_Part_1_3279.html

4

Would like to replace my Shimano 11-23T (Ultegra group) with this one. Anyone had any success or issues? Would like to prevent from having to update the RD.

You’ll be fine. The 6600 series short cage derailleurs can handle up to a 27t cog (I’m assuming this is what you have). You will likely have to readjust the derailleur; namely open up the B-gap. But other than that, you’re smooth sailing.

Also, regarding the chain length issue, there is a chance you’ll need a longer chain, as the difference between big cog and small cog size is larger on the 12-27. But that’s only if the chain was sized improperly to begin with (i.e. too short). We just published a 2-part series detailing this: http://www.slowtwitch.com/...o_-_Part_1_3279.html]

This.

I bounce between a 12-27, 12-25, 12-23, and 11-23 during the season and I never change anything. The bike is set to run correctly on the 12-27 and it works fine for all the others. Granted you could adjust the B-gap and chain each time, but there is no need if you are set for the 12-27 to start with.

5

It’s a 6600 group.

6

Awesome…thanks! Was thinking it should work just wanted to make sure.

7

Very helpful article…good stuff!