Originally Posted by
volosong
As an update...I've been running the Ultegra 12-30 for awhile now, and LOVE it! Most of the time, I don't need that 30t sprocket, but just knowing it is there give me confidence to tackle any hill I come across. When I do elect to use it, it allows me to maintain a much quicker cadence than I would be able to maintain otherwise.
I went and "tested" the cassette on a route w/ 4000+ ft. of climbing (Tour de Peninsula). The cassette gave me no issues whatsoever, even under load going uphill (of course, I wasn't standing, sprinting and shifting uphill). At one point, I was on the 50 ring and shifted to the 30 cog without realizing it. When I saw it, I had an "oh crap" moment and shifted up to the 27 cog (50-30 would probably work fine, but wasn't going to chance it). On the descents, I miss having an 11 cog, but it's worth the tradeoff.