Joined: Apr 2006
Posts: 3,227
Likes: 734
From: Sacramento, CA
Bikes: '64 Bianchi CDM, '62ish Altenburger Cinelli Mod B, '63-64 Cinelli SC, 69 Rene Herse Competition, '71 Gitane SC, '73 Cinelli SC, '73-74 Colnago Super,, '73-74 Cinelli SC, '78ish counterfeit Confente, '82 Medici Gran Turismo, '67ish Mondia Speciale
Good question. I'm on the fence myself, and am also on the bigger side (about 200 lbs). But, I'm inclined to think that, on the paved roads that am almost always on, 28-32 is my sweet spot for tire width. So, if I have a buy a rando frame, I'm inclined to go with 700 c bike. It would be a bonus if it could fit 38s in a pinch.
On the other hand, if you live in areas where trails and gravel are more common, then a 650b bike, with tires in the 38-42 range might be a better choice....
These are just my thoughts, and I'm trying to work through this issue as well...