size cassette for ultegra dr

[reteid]

I am currently running a 25 teeth cassette on an ultegra 6600 derailleur I am thinking of putting a 30 teeth on to make climbing easier for an upcoming race. I wish to know whether I can run a 30T or if a 27T is the biggest I can go with the current derailleur. Shimano says not 30T but different forums indicate that shimano has a conservative approach and that a 30 T can be put on.

 

Any feedback will be appreciated as I do not want to buy and then discover it does not work.

Edited March 30, 2023 by reteid