Originally Posted by milkbaby

There's not going to be a big difference in performance in my opinion -- I have 105, Ultegra, and Red on my bikes and they all work great if you know how to set them up properly. You should try to ride each groupset and decide based on hood ergonomics and shifting feel. Some people are very sensitive to the shape of the hoods, so that can make a big difference in which you prefer. Also, some people prefer either STI or Doubletap shifting, so that is the other main criteria to consider, but explaining it won't help you decide because you gotta try it first hand to find out exactly how they feel and work. There is a weight difference, but that really isn't very important performance-wise.

Originally Posted by jakepounder

But what's the difference? Like as far as performance