I had a 42 on my commuter mtb. Hated it. Changed out for a new crank with a larve 48 and its great. I don't use the top 2-3 gears often, but its good to have them. I noticed that a 21 speed drivetrain benefits a lot more than a 27.With the overlap between the middle and large rings I often forget which chainring I'm spinning unless I meet a long downhill.