Something rubbing but can't find out what

[WorcesteRob]

When out of the saddle on hills really putting the power down I hear a rubbing sound coming from the back wheel area.

I have checked the front mech and this is not rubbing, loosened the rear brake and still hear the noise, any ideas what else it could be?

The bike is my CAAD 9 with stock Shimano wheels and 105 groupset.

 

[palinurus]

Does it only rub when you are in the lowest gear on the cassette?

 

[WorcesteRob]

No, I'm usually in the middle of the cassette when out the saddle going up hills

 

[xpc316e]

Try to ascertain whether the rub is in time with the revolutions of the pedals, or the wheels, or every time the chain passes around the gears once. That ought to narrow things down a bit. Is it a metallic sound of a chain rubbing on something, or the swish of brake blocks kissing the wheel rim? I reckon that it might be the frame/wheel flexing and causing a bit of brake rub - if you are a powerful rider this can easily happen.

 

[WorcesteRob]

Try to ascertain whether the rub is in time with the revolutions of the pedals, or the wheels, or every time the chain passes around the gears once. That ought to narrow things down a bit. Is it a metallic sound of a chain rubbing on something, or the swish of brake blocks kissing the wheel rim? I reckon that it might be the frame/wheel flexing and causing a bit of brake rub - if you are a powerful rider this can easily happen.

The noise sounds like brake rub and not the usual grind from something metallic, my thinking of opening up the brakes (on the lever thingy) would prove this out but still the noise was there. When flexing the wheel when stationary there is a lot of movement so could just be this I guess.

 

[gbb]

Wheel flex ? causing the rims to rub on the pads...
Ive never sensed it in rear wheels, only front, but if you're putting some power down, its possible. Check your spokes for good tension. If any are loose, i suppose that could cause the flex.

 

[Rickshaw Phil]

Wheel flex ? causing the rims to rub on the pads...
Ive never sensed it in rear wheels, only front, but if you're putting some power down, its possible. Check your spokes for good tension. If any are loose, i suppose that could cause the flex.

^ This and I'd also check for play in the wheel bearings. If they're cup & cone type they may need a bit of adjustment.

 

[smokeysmoo]

Have you got guards fitted? Mine sometimes catch slightly when out of the saddle and swinging the bike side to side.

 

[WorcesteRob]

I will have a good look over the bike again tomorrow, its a weird one but something must be causing it.