TriBike Jon

Ok this is a weird one that I can't figure out. I have gatorskins that I use with my cervelo time trial bike to train. As of yesterday my front tire is rubbing on the top of my fork. Here is the kicker, this only happens during climbing. On the flats and down hill the wheel rolls smooth as butter. I took this wheel off three times yesterday during the ride and put it back on. It spins fine with no interference, until I go uphill and start climbing (happens even if I stay in the saddle). Major rubbing going on up hill....? Puzzled? Thoughts?

CliffordK

Are you sure it is rubbing on top of the fork, on not on the sides? You could be leaning the bike during hill climbs.

What size of tires are you running, and how much clearance do you have? I'd probably drop a tire size up front.

Oh, and are you sure it is rubbing on the fork, and not the brakes?

Beach Comber

Even if you stay in the saddle, I assume you're still down low for maximum leverage. Is it possible your spokes are not tight enough to prevent some wheel flex?

Beach Comber

Another possibility is the additional downward force on the tire in contact with the road surface is just enough to expand the tire opposite - which would be close to the fork depending on your rake. How much clearance do you have between tire and fork with no additional downward force (e.g. level riding)?

TriBike Jon

I am riding with a 700x23c tire. I have clearance between the tire and the fork, not sure exactly how much. The odd thing is that I have been riding with this setup ( exact tire and bike). Without any complications until now. I am sure it isn't hitting the breaks and it isn't happening on movement side to side. The loose spokes creating wheel flexibility is a possibility I haven't thought of....

Wanderer

Is your wheel resting on the axle, and not on the quick release********** Ck the bottom of that fork.

CliffordK

Look for scratches and wear marks on your fork. That should help indicate if and where it is rubbing. Also make sure the wheel is centered between the two fork blades.

Post some photos of the bike and fork, looking from the side, and direct from the front.

FBinNY 

If your fork has an arched top (actually the bottom, or ceiling), then it's very possible that a tire that clears in the center will rub if deflected to the side. I'd steal some finger paint, or whatever from the local kindergarden and paint the ceiling. Then ride those problem hills and see where the rub is.

That would solve your mystery, but the only practical remedies are a narrower front tire, shimming the dropout a bit (1mm or so) to gain clearance, buying or building a laterally stiffer front wheel, or modifying you riding style to reduce side loads.

TriBike Jon

Thanks for your insight.

hueyhoolihan

from those pics, if the tire is indeed hitting the fork, then it's got to be flex. i was thinking that it was hitting the top of the fork, but can't imagine that being the problem now.

might want to check for a loose skewer and spoke tension, broken axle, worn-out bearings.

try a different wheel, or tire, or both. eliminate possibilities, 1/2 of them at a time, if possible .

TriBike Jon

will do thanks!

FastJake

The first thing I would suggest a frame/fork with less ridiculous tire clearance...

But you have enough room that you shouldn't have rubbing issues. First thing to do is make sure your QR skewer is nice and tight. Then try grabbing the wheel by hand (not while you're riding!) and see if you can get any side-to-side play to show itself. That indicates loose bearing adjustment. Also grab each pair of spokes to make sure you don't have any loose ones. If all that checks out my original suggestion remains.

FBinNY 

I earlier posited side deflections as a possible cause. But seeing your photos's, I'm suspecting that isn't the case. Unless the wheel rises significantly when the fork is loaded, the amount of deflection needed in any direction to cause fork rub, is too great.

Jusr eyeball estimating, I suspect the wheel would rub the brakes long before it rubs the fork. So, you might not even the paint experiment, pull the wheel and look for scratches or buff marks on the fork. If there aren't any other than what a thrown stone might do, you know it isn't fork rub. If you do see marks, then the paint will verify when, where and how they got there.

Meanwhile, consider your assumptions, go out and ride and watch and listen to see if this is a simple matter of brake rub.

Drew Eckhardt 

Tension has no impact on stiffness because it doesn't change the spring constant.

FBinNY 

Thank you, that groove in my record is worn out from overuse.

Flex is a function of the amount of spoke (number and/or thickness), not tension.

jimc101

Whatevers going on, from the pictures, the brakes QR is undone, this should be closed before riding

Al1943

+1 I also noticed this and wondered if the brakes are properly adjusted. I've found that people who ride with their quick releases open often have other adjustment problems. But that may not apply to
the OP's case.

CliffordK

Good points, loose bearings could cause quite a bit of wobble.
WH-R501 sounds like a Shimano wheel/hub, so it should be cone & cup bearings.

Of course, also make sure the wheel is true.