Originally Posted by McBTC

At 6' I think you're probably just a few inches short of making either bike's largest frame size easily work for you (both probably will require futzing around a lot with stem length and saddle positions-- you're probably looking at what size equates to a 'virtual' seat tube length (i.e., no C-C) of not more than ~25" (63.5 cm). For the LHS, for example that looks like the 62 not the 64. For the 520 I think you're stuck with making the largest size work--the 63... perhaps just a tad big but the next size down may be a bit too confining. With the headtube size of Trek's 63 you'd have no problems with more upright seating and you can always spend more time in the drops in headwind situations.