Sjtaylor

I’m experimenting with what tire size will fit on my Trek 770. I think it was probably sold with 23c tires. I just installed a Bontrager AW2 700 x 28c tire on the rear. I couldn’t fit the wheel by the chainstay bridge with the tire inflated. Once in place with the tire reinflated the clearance looks okay.

Is it common practice to have to install a wheel with the tire deflated? Am I pushing the limits by the clearance I have with the new tire? The tightest clearance is where the tire fits between the chainstay tubes. With the wheel perfectly centered there is about 3/16” clearance on each side.

Thanks.

Andrew R Stewart 

As long as you don't pick up any road grit (pebbles, chip seal or glass as examples) larger then the clearances you have AND you don't allow the rim to get out of true too much there is no problem. Don't be surprised if you see scratches in the paint about the close clearance points in a while though.

As far as fitting the wheel with a soft tire- that's no issue unless you can't inflate a tire while it's mounted in the bike

A common dimension of clearances is with fenders at least 10mm between the tire and the fender. My newest bike has about 5-6mm of sideways clearances in the rear. But the top of the tire is only 2-3mm from the caliper's undersides. I hear/feel road bits running into the caliper often. I should have brazed the bridge a couple mm higher... Andy

Sjtaylor

Thanks. I mentioned in an earlier post that the little dropout axle insertion limiting screws were screwed way in. I think I can pull the wheel to the rear 3/8” if I back out those screws. I may play with that.

seedsbelize 

I have to deflate to install 25mm tires on my two early Treks. I don't think I'd bother with trying 28 mm on either of them. 80 414 and 79 930.