Originally Posted by
banerjek
Since you have the 30T ring, I agree with dstrong's advice to go with a 12/21 or 12/23.
With 3 rings, there is no point in having a wide cassette since you don't have big climbs, there is already plenty of overlap, and the jumps between gears will be much smaller.
I was thinking about just changing the chain, but I'm starting to lean towards getting the more compact cassette. There have been several times (especially when I'm tired) where I felt like the change in gears was too big. Meaning I couldn't comfortably cadance at either one. So the 12/21 sounds like it may be ideal.
Looking at the link that Mr. Beanz provided, it appears that my rear cassette is a SRAM. Would it be smart/easy to just use that brand again, or does that really matter (hope I'm not opening up a bag of worms with that question) Or maybe it would just be easier to use the brand my LBS prefers?