thats an awful bike shop if they told you that at 5'10 they didnt have a frame to fit you. they must not want your money. utter b.s. Im 5'10. I ride a 55cm road bike. my mtb is a 16 inch frame but it is too small for me. I need to jack the seat post up all the way to the minium insert line. I have no issues w/toe overlap or heal strike or anything, it is still plenty ridable just not ideal. My wifes mtb is an 18 inch which I feel alittle streched out on. Obviously I need a 17 inch frame.
__________________
2010 Kestrel RT900SL, 800k carbon, chorus/record, speedplay, zonda
2000 litespeed Unicoi Ti, XTR,XT, Campy crank, time atac, carbon forks