I did some jumps today to get some snap back in the legs, and I noticed that while sprinting out of the saddle, my front wheel rubs the brake on my left down stroke.

Stats:
Fork: Older Look carbon (from 1996)
Wheel: Forte Titan (16 spoke 1x with 27mm rim)
My weight: 150

Is it just a flexible fork or the wheel?

It's going to be some combination of both. You could try taping a straight-edge to the fork blade (masking tape), push the top of the wheel over to the brake pad, and see if the straight edge moves relative to the fork.

I'll bet it's mostly wheel though. 16h, low flange, medium depth rim.

You're probably right that it's both. *sigh* I'm no longer such a flyweight that anything can withstand me. Oh well, I hope I find enough cash to upgrade things before I find myself contending for the sprint in any races.

It also could simply be how tightly the skewer is clamped

Probably both, but...

There is an easy way to find out: borrow a stiff front wheel (Ksyrium or the like) from a friend or bike shop, and see if it still rubs.

I've heard that the look 1" carbon steerers where known to flex quite a bit (good ride, but a bit flexy when torqued). I have a 1-1/8" Look HSC3, and it's fairly stiff, but will still flex when sprinting/climbing (doesn't rub tho).

OP - You can lessen the wheel flex by checking and judiciously tightening spoke tension. May not be enough to eliminate the problem, but should help a bit.

We'd be concerned with crown and blade flex, right? Flexy steerer wouldn't cause brake rub.

I normally ride on a 32h 3x wheel but haven't done as hard of efforts on them as I did yesterday, so maybe I'll throw that back on and see.

Correct, the steerer tube wouldn't make a difference. Mine is aluminum or steel anyway (we're talking 1996 threaded here, folks) but I do recall reading somewhere that the Look had the worst deflection rating in a test in the late 90's.

I'm tempted to raise the spoke tension, but they seem to be at a quite appropriate tension already. They're almost as high as the drive side rears, and I imagine that's not too far from the highest recommendation.

Oh, and as far as skewer tightness, would tighter or looser generally solve the problem?

In order for a "looser" skewer to mitigate fork/wheel flex it would have to be loose enough to allow the axle to travel in the dropout, which would not be a good thing.

Is the headset 100%?

'96 pre lawyer tabs?

^ Yes, the headset is in good shape. I can't see how that would make a difference anyway.

The fork has lawyer tabs. The skewer should be tight enough, although I could give it another twist to be sure.

Yes, steerer wouldn't cause brake rub, right. Not sure if the rest of the fork was flexy though...that was the reputation.

Anyway - again, easy to isolate fork vs. wheel by putting on a known stiff front wheel. Still occur? Fork.

Maybe you're riding too hard. Ease up and see if that makes a difference.

LMAO My first race of the season is tomorrow. I'll let you know if I should ease up or HTFU then.
Seriously, weighing 150 lb and not having all that much wattage, I didn't think I could accomplish this little nuisance.

Tomorrow!?!?! Damn, we just got more snow. You Californians! I'm so jealous!

Yes, although it's expected to be marginal weather tomorrow. "Marginal" means temps in the 50s, overcast with a slight (20%) chance of light showers.

My coworker's daughter lives in Michigan and told her they got 11" of snow yesterday!

I had to return a set of those wheels because they flexed way too much for me, not even just on sprints/standing (I am usually within a few pounds of 172 or so).

Hmmm I wonder how long Performance will allow returns for. I'd love to get a set of tubulars for racing, but just can't afford it right now.

I tested it, and the 32h Reflex wheels don't flex quite as much. They still creep toward the brakes when I lean on the bike hard (standing still), but not as easily as the Titans.

Lots of stuff flexes too much, and I reckon lots of guys don't even know they have a flexy bike, especially 'normal' rims with low spoke counts. I've got rid of a few wheels and forks because they were too flexy.

This is what ya need: a 1" ITM Visia fork (alu steerer) and 30mm-deep 32-spoke wheels! STIFF as bricks!

Fixed But if I wanted to race on a 2000g wheelset, I'd just race on my Reflex/Ultegra wheels.

yeah, fair enough, but MAN is it good to mash off the saddle and have the front end as solid as a rock

Angus and headbanging and extra o2 have their place. A nice smooth ride does too...stiff as bricks (and light) is nice, great at times, but trade off a bit less stiff and very compliant and the road feel/ride will put you in a riding buzz that will make you forget the ACDC riffs for a second.

Pisser that the cypress banning post was closed. Mods, this kinda crap makes you loose us.

^ ha Yes, but this guy is talking about 'jumping' and sprinting out of the saddle