Road Uni Tire Clearance?

Here’s a general question about clearance between the frame and the tire on a uni intended to be riden on the road.

In searching in the archives for information on tire clearance I came across quite a bit of discussion with regards to clearance for MUni tires both under the crown and along the forks. But I haven’t read much about is clearance for, say a Big Apple on a 29’er frame.

Of course less clearance would be necessary between frame and tire for a uni that will not be encountering mud and loose riding surfaces. So what set up are you riding on the road and how little clearance are you getting away with? Do share.

If it don’t rub you got enough clearance.

That’s probably true for the Big Apple and smooth road tires. I’ve got Blue Shift on loan from Harper with a Big Apple. It’s clearance is so tight you can’t see daylite between the crown and tire. Its picked up some road grit but nothing that affects performance.

A tire with more aggressive tread may pick up more stuff than the B.A.

Fortunate for you the B.A. is as big as it gets.

Paper hin clearence is OK on a road tyre so long as you watch WHAT your riding in! new laid or really soft in the sun tar and chippings can cause a problem, even with a bigger clearence. I had a face plant from the coker thanks to picking up a tarry chipping like that on the C2C ride the other year!


Yikes! :frowning:

Double Yikes!!

Sorry to pick-up on an old thread, but this one is interesting.

It seems that a few are suggesting that paper thin clearance is fine for the road.

I have found that tire dimensions can change quite a bit from cold (before a ride) to hot (after riding awhile). The Big Apple is a large volume tire and expands a bit after turning the cranks for a few miles.
I was going to take a few pics for illustration but found this gallery that pretty well shows it (center photo and text):

Several considerations. Would you want your uni to be restricted to tarmac and concrete by the tyre clearance? All my unis get ridden across rough ground and muddy paths from time to time.

If a tyre picks up mud and grit, it will at the very least scratch the inside of the fork. At worst, it will cause damage, or a UPD.

And few wheels stay perfectly true forever. If you have minimal clearance, then you will be stuffed if you put the slightest kink in the wheel.

Also, a uni frame can flex considerably under heavy pedalling - e.g. up or down hill. I’ve heard my Coker tyre whiffing against the inside of the forks from time to time.

So, rule of thumb? I wouldn’t be happy if the gap between the tyre and the fork was too small for me to pass my finger tip through. OK, that’s a rule of finger. :roll_eyes: