Kid has outgrown his bike after only 2 years (sob), so I need to get him a new one and want to buy used. He's almost 16, 6'1" or maybe a bit more with long legs -- he wears 34 inch inseam Levi's and they're a little short, though 36 would probably be a bit too long. Short torso. Would prefer not to torture the both of us by going through a measuring scheme like on Competitive Cyclist. If I'm looking on craigslist, what size should I start with as a baseline? 58" road? He's currently riding a Marin hybrid 19".

Alternatively, is there any way to extend the seat post higher than what came stock? He says the reach is fine, but his knees are really bent even at the bottom of his stroke.