This is a very useful thread. My bike currently has SRAM Rival components, 50/34 compact double with an 11-28, 10 speed cassette. Last fall I found myself walking up a particularly steep climb (it was that or fall over with an asthma attack) as I watched my friend effortlessly spin up to the top with her mountain-bike gearing. That was when I decided my next cassette would be better for climbing. Given the rides I'm planning this year, I think it makes sense to keep what I have until it wears out. When that happens I will be wondering the same thing -- what cogs do I want on the new cassette. So this is giving me an idea of what to look for.

Thanks!