The Cannondale geo is a little different than most. I'm a solid 5'10" with a 32" inseam and I rode a 54cm and I felt it was small, but that was me. You need to ride one to get an idea of how they fit.
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I'm not one for fawning over bicycles, but I do believe that our bikes communicate with us, and what this bike is saying is, "You're an idiot." BikeSnobNYC