Originally Posted by
mavericg
I'm torn with the sizing because being 170cm shows it's the higher max end of a Small while 170 being the starting point of a Medium. I've rode Medium but the Small isn't available for comparison.
Were you comfortable on the medium? Good on stand-over, or marginal? Good on reach? I know it's easy to say, but I'd focus less on the numbers and more on how you feel on the bike. The shop doesn't have a single Roam model in small? If you're buying a Roam 1 (high end model), perhaps they'd agree to bring in a Roam 3 (bottom model) in small for you to test the size. They'd probably be able to sell a Roam 3 or 2 pretty easily (due to the lower cost) and the size would give you an idea of what the small would feel like.
Failing that...if you think you'll always question if medium is too large (if you're torn now), then order in the small and have the shop install a longer stem or even a set-back seat post if necessary. I think it's easier to "make a bike larger" than it is to "make a bike smaller".