Originally Posted by
FL_Gator
I built my road bike for flat Florida speed with an 11-28 rear cassette (50/34 front). ... I’m wondering if I can use an 11-32 on my trainer and the 11-28 on my bike without any issues? I already have the larger Ultegra rear derailleur installed.
Not unless your existing chain is (1) very worn, which would prematurely wear out your new cassette or (2) sized just barely long enough for the existing 11-28 cassette, in which a case a shift to the big-big combo using the new 11-32 cassette may break your RD.