just another gosling
Join Date: Feb 2007
Location: Everett, WA
Bikes: CoMo Speedster 2003, Trek 5200, CAAD 9, Fred 2004
Since there's only one hand position and frame size in this model is mostly about top tube length, yes, the wrong size would be a bummer. Knee pain won't have anything to do with frame size, just saddle height, which is adjustable. But yes, if the LBS got it way wrong, could be. A wrong size bike of this sort would be less comfortable, but probably no serious medical consequences.