Originally Posted by
Mr. Beanz
1.2 Trek, I see it in the pic now....50/39/ 30 crank with a 11/26 cassette
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.