
Originally Posted by
alpinerabbit
OK, let's put it this way: if you can get the correct knee over pedal axis position on either frame, with saddle positioning/seat post, get the smaller.
If you can't, then don't - but I've learned to err on the side of small, all I'z sayin'.
You just took the words out of my mouth. You ideally want a bike that allows you to get your weight properly centered behind the cranks and your knees somewhere either above or slightly behind the pedal spindle. You might want to read the "fore aft" part of the following article on bike fit: http://www.peterwhitecycles.com/fitting.htm
To figure the above out, the shop has to be willing to put you on a trainer and to make the necessary adjustments.
From there, check your reach, keeping in mind that reach can be shortened or lengthened to some degree by changing the stem length and rise. Your choice of bars may also help.
I, personally, think it's easier to make a small bike bigger than to make a bigger bike smaller--within reason.
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