My flo wheels do that in my 2014 p2 140lbs

The carbon rim is actually very stiff, but, yes, low spoke count wheels do flex a fair amount, depending on the force applied and the weight of the rider.

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Then I'm even more confused why this is happening now. This whole rubbing thing started with these wheels. Aside from the initial rubbing against the frame i haven't had this happen in 2 years. The wheel was just trued and even if it were an untrue wheel, it would rub all the time, not just climbing, and it's not a low spoke count either.

Not sure what to think, Guess i'll just keep my brakes farther apart than I'm accustomed to.

What wheels are they? Some frames have issues with the wider toroidal rims. But, since that is the trend with wheels most frames have adapted. I would assume that's not the issue on a 2012 bike.

That said. Carbon is very stiff. If you have a normal spoke count the issue could be that the wheel is actually so stiff you are flexing the frame when under high torque, like when climbing. I noticed this a few years ago. Its counter intuitive but it does indeed happen. Depends on the wheel brand, depth of rim, type of frame etc.

I would guess that could be the issue. An aero bike will used bladed tubes for aerodynamics. However, this will make the "tube" very stiff along the long axis and compliant/flexie on the short axis. When you are climbing you will be putting more lateral force into the frame. Some of those forces may be effecting aero tubes, and thus causing flex. There's a lot of ifs and maybes there but my guess is that the frame is flexing not the wheel.

Hope that helps.

Jimmy

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Jimmy Archer

I'm not sure that I'm following you after your last post - thought the wheels were new as of X-MAS with little use. But 2 years and just trued and now rubbing changes things up a bit.

Deep carbon wheels are *generally* pretty stiff, but the actual characteristics really depend on the carbon layup. Hard to say what QC and engineering goes into a nondescript Chinese wheel set - could be state of the art or maybe not.

If you were switching from another set of rims to these, the rim width could be a mm or two wider at the brake track and therefore closer to your brake pads than old rims. They may flex the same or less than old rims, but because they're wider they make contact, how much lever travel do you have? Not uncommon for strong /heavier rider to flip release lever on extended climbs to prevent pad rub.

This wouldn't explain sudden rub after truing unless brakes were also adjusted.

http://www.slowtwitch.com/Tech/Debunking_Wheel_Stiffness_3449.html

Check your hub bearings for play.

I believe this to be the case; with aluminum wheels/rims, you're able to flex the rim itself, due to the spokes having such high overall tension and being stronger than the rim material.

When you move to a deep or stiff carbon wheel, the carbon itself is so stiff that it can lead to frame flex and wheel rubbing on brake tracks.

Here's a great link for everybody's viewing pleasure.

http://www.rouesartisanales.com/article-23159755.html

If your brakes are making full contact at approx half lever travel, and you cannot bottum out the lever on the bar then your pad clearance is optimal..

if you still rub then there is an issue...

Are you tightening the QR's sufficiently? If you hve superlight ones consider Shimano closed cam (DA for instance) or DT swiss steel RWS skewers.. This will at least ensure any movement is no in the wheel or the frame.. for a cheap version have a look at the bolt up style QR's.. they achieve higher clamping forces are aero and simple.. just slower than a QR.. if that matters..

Re the wheel, it may have lost some of its tension, you mentioned you had it trued recently.. get the spoke tension checked as well (and not plucked.. ) actually measured to spec..

If it still persists, then it is liklely the wheel is actually too stiff for the bike, here's why; flexible wheels actually bend at the point of side load ie the base (at point of contact ie oppostion to the side load through tyre grip) and return as side load is relieved.. ie toward the top..
Stiff wheels do not, think of them more like a disc.. as you move one side out of plane the opposite will match it because it cannot flex. and side loads twist the whole wheel out of plane causing rub....

Only real solutions are; a softer wheel, lower side load (smoother technique) or correspondingly stiffer frame... or perhaps a longer pull brake allowing a wider initial clearance... or DISC brakes.. (but you'll get occasional disc rub there too pending set up.. ...)