side_FX, as a follow-up, I grabbed the wheelset off a Trek Lane and crammed it onto a 1.2 to see if the 1-series can handle 700 x 32 tires. The tires on the Lane are legit 32s that actually measure a full 32mm wide, with lots of tread depth. BIG tires. They're too big for the 1-series; the rear tire hits the backside of the frame's seat tube just above the front derailleur, and the front tire would hit the inside of the fork legs when the wheel flexed slightly.
So 700 x 28s, or 700 x 32s that run smaller than their nominal size, would be the limit. You want some room between the tire and the fork legs or rear stays, to allow for wheel flex and out-of-true wheels.
Last edited by mechBgon; 12-24-11 at 04:13 PM.