Originally Posted by
Al1943
A quick Google search found several 10-speed 12-27 cassettes available including the 6600. An 11-28 combined with a standard triple seems like overkill on both ends. Why not replace the 12-27 with another 12-27?
Like I said in the OP, cost is one reason: 11-28 is cheaper. The other is the 11-28 will be handy from time to time on my racing bike, which has a 53/39 crank.