carbon wheel flex - when it's too much

actusreus

Recently bought a pair of the Enve SES 3.4 clinchers, and have been getting the brake pads rubbing against the rear wheel rim with every rotation of the drive side pedal, even when sitting in the saddle and not winding up much. The wheel appears true when spun when the bike is stationary. How much flex is acceptable in a high end carbon wheel? I opened the calipers and the rubbing and noise went away. I'm about 5'9" and 160 lbs so pretty much an average rider. Does the spoke tension need to be adjusted?

DavidJB

actusreus wrote:

Recently bought a pair of the Enve SES 3.4 clinchers, and have been getting the brake pads rubbing against the rear wheel rim with every rotation of the drive side pedal, even when sitting in the saddle and not winding up much. The wheel appears true when spun when the bike is stationary. How much flex is acceptable in a high end carbon wheel? I opened the calipers and the rubbing and noise went away. I'm about 5'9" and 160 lbs so pretty much an average rider. Does the spoke tension need to be adjusted?

Pretty much zero flex is acceptable.

gweeds

What frame?

actusreus

Gweeds wrote:

What frame?

Pinarello Dogma F10

gweeds

Ok - so not a flexy frame then...

fenix

Have you tightened it sufficiently in the drop out ?

Maybe try a different skewer ?

Theres no way you should be getting flex like that.

actusreus

DavidJB wrote:

actusreus wrote:

Recently bought a pair of the Enve SES 3.4 clinchers, and have been getting the brake pads rubbing against the rear wheel rim with every rotation of the drive side pedal, even when sitting in the saddle and not winding up much. The wheel appears true when spun when the bike is stationary. How much flex is acceptable in a high end carbon wheel? I opened the calipers and the rubbing and noise went away. I'm about 5'9" and 160 lbs so pretty much an average rider. Does the spoke tension need to be adjusted?

Pretty much zero flex is acceptable.

Actually, some flex is normal and necessary, at least according to Enve, which makes sense to me. Spoke tension or the skewer are the likely culprit, I'm told. Having it checked tomorrow so I'll report back.

DavidJB

actusreus wrote:

DavidJB wrote:

actusreus wrote:

Recently bought a pair of the Enve SES 3.4 clinchers, and have been getting the brake pads rubbing against the rear wheel rim with every rotation of the drive side pedal, even when sitting in the saddle and not winding up much. The wheel appears true when spun when the bike is stationary. How much flex is acceptable in a high end carbon wheel? I opened the calipers and the rubbing and noise went away. I'm about 5'9" and 160 lbs so pretty much an average rider. Does the spoke tension need to be adjusted?

Pretty much zero flex is acceptable.

Actually, some flex is normal and necessary, at least according to Enve, which makes sense to me. Spoke tension or the skewer are the likely culprit, I'm told. Having it checked tomorrow so I'll report back.

My FFWDs didn't flex, my Campagnolo bora's don't flex, my zipp 404 firestrikes do a bit (I think...might just be the hubs) which is highly annoying.

I'm 151lb, I'd expect it for a 180lb sprinter.

Anyway "flex a little bit" or not you shouldn't be getting that kind of flex.

alex222

Very topical. Too much flex in this carbon wheel
https://www.youtube.com/watch?v=jxeyI_B4nEE

actusreus

DavidJB wrote:

actusreus wrote:

DavidJB wrote:

actusreus wrote:

Recently bought a pair of the Enve SES 3.4 clinchers, and have been getting the brake pads rubbing against the rear wheel rim with every rotation of the drive side pedal, even when sitting in the saddle and not winding up much. The wheel appears true when spun when the bike is stationary. How much flex is acceptable in a high end carbon wheel? I opened the calipers and the rubbing and noise went away. I'm about 5'9" and 160 lbs so pretty much an average rider. Does the spoke tension need to be adjusted?

Pretty much zero flex is acceptable.

Actually, some flex is normal and necessary, at least according to Enve, which makes sense to me. Spoke tension or the skewer are the likely culprit, I'm told. Having it checked tomorrow so I'll report back.

My FFWDs didn't flex, my Campagnolo bora's don't flex, my zipp 404 firestrikes do a bit (I think...might just be the hubs) which is highly annoying.

I'm 151lb, I'd expect it for a 180lb sprinter.

Anyway "flex a little bit" or not you shouldn't be getting that kind of flex.

My mechanic tightened the spokes and it seems to have taken care of the rub. I still got it on a steep climb out of the saddle yesterday, but just a little bit. I quoted DavidJB's post because, coincidentally, BikeRadar has an article regarding this very issue posted today where they tested a few sets of carbon wheels and two carbon frames. There is always flex in a carbon wheel, so saying your wheels "don't flex" is scientifically specious. Perhaps your brake calipers were farther than 2 mm from the rim, which appears to be an average flex, or your don't get out of the saddle ever, but as the test showed, carbon wheels will flex when there's force applied to them such as when climbing out of the saddle, including wheels used by professional teams.

The Rookie

remove 'carbon', all wheels flex.

Carbon slightly less so as the rim is stiffer than aluminium, but apply a sideways force to the rim and clearly it will move as the spokes stretch slightly, hub distorts slightly etc.