I have a carbon rear rim that started to flex and rub on both brake pads. Wheel seemed true, but spoke tension was very loose on a few spokes. LBS confirmed the same and re-tensioned the wheel. Did a few rides after and it seems the same. Return trip to LBS and they say the wheel is fine. I feel like I will have to buy a tension gauge for myself. Just wondering if I’m missing something.
Some carbon times just flex with your out of the saddle climbing. Mine did at least and I never thought it was off. I’m not a wheel expert tho
The spokes on the same left/right side should be the same. When you’ve got a real wheel or disc front, you’ll have vastly different tension. How much pad clearance do you have?
Clearance is just under 2mm each side. There are two or three spokes next to each other on the same side that are noticeably looser.
Get a phone app for spoke tension. Note that how semi-flat and flat spoke sound will depend on how they lay on one another. Spoke Tension Gauge on the App Store
That value it spits out is only useful for relative tension, not correct tension, so just check it to the other spokes.
Wow that’s pretty cool. The theory is sound :-P, but I wonder about the execution, relying on the phones microphone. Have you tested this against a spoke tensionmeter?
Yeah, its more reliable than the spoke tension meter up until final tightening. Again, you need to make sure the spoke are lying on one another correctly. At final tension, you tend to get a lot of crosstalk between the long and short sides of the spoke and you’ll get two different readings.
This is interesting. I gel like this may leave more room for me to screw up though.
Not saying for sure this is the case here but, perhaps counter intuitively, a rigid rim is can be more likely to produce brake rub not less.
On a completely rigid rim any small movement at the bottom in contact with the ground will be mirrored at the top near the brakes. A floppy wheel will move more at the bottom but because it bends the movement isn’t mirrored and there will be little or no brake rub.
If you genuinely have loose spokes though that’s a problem.
The problem may only present itself with the tire inflated because the air compresses the rim.
Sorry but I just had to link to this article by Sheldon Brown regarding spoke tension by pitch.
What wheel is it? I’ve seen Mavics with bladed spokes with no measurable (on a tension meter) tension in the NDS spokes on a rear wheel.