New set of wheel ps on the roadie. 5th ride in I can hear rubbing when standing and cranking more than 500w. I didn’t notice this in the first 250 or so miles. It appears to not be the brake blocks as I wound them off so it is the chainstay 🙁

Could the preload need adjustment? Holding the rim I can flex the wheel a little side to side in the frame.

These are a set of zipps so not a cheap set….I’m not that heavy either at 75kg.

Wheel flex and loose bearings aren’t normally easily mistaken.

How else do you think Zipp achieve such low weight? They’re notoriously under-build and flexy as a result. If you want something stiffer, look at Mavic Cosmic Ultimate or Enve

They are 404s and weigh in at something like 1650g about the same as the cosmics sls.

I’d expect some rub at higher wattage at the brake blocks, not at the chain stays…when I get a spare 10 mins I’ll have the wheel out to take a look. Just seems odd. It was also only on the left downstroke as well. I hope I haven’t cracked another frame 🙁

If you don’t have enough preload the wheel will clonk from side to side (eventually) as the bearings will run loose. It won’t flex.
If you have the right preload there will be no clonk.
If you have too much preload, the hub will drag.

I reckon what you’ve got going on is low spoke count, low tension or a poor wheel. Or not enough clearance. Wheels flex when you sprint, IIRC worst case for rubbing is a stiff rim and low spoke count/low tension.

How much space between tyre and chainstays in the stand? (You might just need smaller tyres, just had to deal with this for a mate, large 23s on wide rims were rubbing the stays)

Zipp are flexible under power, especially if stood climbing. Was very surprised when I first road a pair of 404, but you remember what they are for.

Personally like shimano c50 if wanting a tighter feeling deep section

Had time to take the back wheel out and take a look. No real marking on the chainstay, so I think I must have been mistaken, it must be the rim / brake block. Next ride I’ll back the brake right off (I just used the adjustment on the caliper). There is a fair bit of clearance, the tyre is a 25. All the spokes feel tight.

Rubbing starts at 600w when stood up, 600w seated doesn’t seem to do it. Its a bit off putting to say the least. Might have happended with the old wheelset and the noisy zipp pads/rims have made me notice more.

Bit worried about the wheels longevity if they flex at that power

look at the brake caliper – shimano ones certainly have a bulge on the inner face that comes close with bigger tyres