I'm looking for a new bike. I've only started cycling and I've been using a single speed my brother left. It's a very nice bike but it's not what I want and it's also not really mine so I feel weird riding it. I don't have much money to spend but my parents are willing to help me get one. I was bumming on craigslist looking for one and found this. Click
It's what I'm looking for but my dad isn't sure about the frame size. I'm a bit under 5' 11 with about a 31 in. inseam. 55cm might be a bit small for me but is it really that crucial?
I just don't think that's a 55 from the looks of it. It looks like a 51, maybe. 55 or 56 sounds actually close to about right for someone with a 31 inch inseam.
You can always email the seller and ask them to measure the standover height for you. It's almost never a problem. However, I think that bike is smaller than 55. The length of the top tube is important to avoid a cramped feel, and even if you bought an extra long seatpost, it would still be too short lengthwise. Stems don't get much longer than about 130mm.
