Large adult son wants to ride

[KnottedYet]

I like the shop already: Surly and Kona! My two favorite brands!

Sounds great that they are inviting him in to come watch the set up. (bring them some beer, beer makes happy wrenches! Tom's party store on the north side of Grand River, right at the East Lansing/Okemos border has the best beer selection.) I hope he goes on the weekly ride, there is nothing like riding with other folks to help you learn!

Hooray!
(and even though it's not *your* bike, we want pictures of course!)

[boy in a kilt]

If he's that big (and I'm sure that'll change), don't let them talk him into the following follies:

-any weight supporting element that involves carbon fiber
-As eden said, wheels with less than 36 spokes. I'll add a bit and say he would do well to go with wider rims that can handle 35C tires or better.
-I would almost recommend he go with upright (e.g. moustache) handlebars. If he's that large, he will find the upright position much more comfortable. He can go with drops later if he's so inclined. Might even be a good motivational tool.