As long as the 11-28 is compatible, yes. Keep in mind that the 8 spd cassette is about 5mm's narrower than the 9 spd, so you'll have to compensate for that.pdxtim said:I have an Ultegra 9 speed compact double with an 11-25 cassette. I'd like some bigger cogs in the back and have an old 8 speed cassette, 11-28. Can I replace the 9 speed cassette with the 8 speed? Thanks.