by Graham O » Wed Jun 06, 2007 11:21 am
I have bought a 12-27 recently. The only diffference between the 12-25 and the 12-27 is the top two gears. Basicallly its;
12-25 = 12,13,14,15,16,17,19,21,23,25
12-27 = 12,13,14,15,16,17,19,21,24,27
Most of the time, I am sitting in the 12-21 range and this is exactly the same on each. The 27 gives you that extra gear for the 1 in 4's..