Idiot stumped by rubbing sound

[palinurus]

Clicks and creaks can be hard to pin down.

This one should be obvious though.

I've got this shss-shss-shss noise. About three per pedal revolution.

It sounds exactly like a mudguard rubbing on a tyre, and of similar volume (it's not like a barely detectable noise)

And I do have mudguards.

And tyres.

But I've checked several times and there is clear space all around the 'guards and stays. I've spun the wheels and I can't see any or hear anything rubbing.

When I say several times I mean about 20 times.

Nothing obviously fouling the hub bodies.

Chainstays are wide on this bike. Miles away from the tyre.

It isn't the front brake rubbing because today I unhooked the bendy doodad on the V-brake from the thingy on the brake arm so the brake arms were all floppy and rode the bike like that (my first experience of brakeless fixed btw).

shss-shss-shss-shss

It isn't the rear brake rubbing because there isn't one.

Front hub is an ageing dynohub. Figured it might be that, outside chance. Put in another -known good- wheel.

And left the brake unhooked for good measure.

shss-shss-shss-shss

I put the bike upside down and spun the pedals. No similar noise from the rear wheel or hub. Chainring, cog and chain were all replaced at the same time earlier this year but I have had the rear wheel off a couple of times to change tubes- didn't notice whether the noise started after this as I haven't ridden it much recently.

I don't get it.

 

[steve50]

tyre / road noise noise from rear wheel? have you checked the tyre pressure or condition of the rear tyre itself?

 

[JtB]

I had a rubbing sound on my old bike from the rear tyre when pedaling but when I spun the wheel it was free. Turned out the axle had broken and the wheel was twisting when being driven.

 

[davidphilips]

mudguard has to be high on the list of known offenders, try removing it test the bike to see if noise goes with guard,lol, fun you can have with this is if noise is still present and then you refit guard the noise may now be in stereo.

 

[fossyant]

Stuck leaf in the guards

 

[palinurus]

Stuck leaf in the guards

I've had both wheels out in the last couple of days. I'm still going to have another look!

mudguard has to be high on the list of known offenders, try removing it test the bike to see if noise goes with guard

I might well remove the guards at the weekend- even though I can see they aren't touching the tyres I could still do with convincing. Every few hours I think 'I'm going to have another look at those 'guards…'

I checked the mudflap too. More than once.

 

[Deleted member 1258]

What bracket attaches the mudguard to the rear brake bridge? If its the one that folds under the mudguard check under the mudguard and make sure the four little arms are clear of the mudguard.

 

[Ajax Bay]

I've got this shss-shss-shss noise. About three per pedal revolution.
It sounds exactly like a mudguard rubbing on a tyre, and of similar volume (it's not like a barely detectable noise)
. . . . I've checked several times and there is clear space all around the 'guards and stays. I've spun the wheels and I can't see any or hear anything rubbing.

Depending on the gear, your (rear) wheel(s) will go round about 3 times a pedal /crank revolution (eg 50/16). So this is a part of the tyre/wheel combo fouling/touching part of the bike (a bit attached to it, anyway). If you select a really low gear is the frequency the same (I expect it to be less frequent ie just over once per turn of the cranks).
OP says: "I put the bike upside down and spun the pedals. No similar noise from the rear wheel or hub." So when the bike is unloaded this does not occur.
When you checked (20 times) you were not sitting on the bike. My best bet is that this is the central (ie rather than side) of the tyre touching the mudguard bridge (you know, the metal one you fit attached to the seatstay bridge). The wheel may be not quite true vertically and at the high point is doing the fouling (as
@dave r has suggested). But thing is that it's no good looking at it, because you need to have your (or another's) body load on the wheel to get the effect. Take the rear mudguard off (as @davidphilips has suggested, or you could just remove the mudguard bridge attachment by unfolding the two/four arms and try riding it to see if the pssh pssh pssh is still there.
What rear tyre are you running? Check whether the rear wheel has some 'up and down' in it. You may be able to sort this with a spoke spanner (but let's see if this is the issue first).

I have had exactly this after fitting an M+ 28 (in place of another 28 which had started a sidewall bulge) and thought it was fouling on the mudguards by the chainstay bridge. I cut some of the mudguard away and it seemed sorted. Setting out on Day 5 of LEJOG (220km, longest of the trip) and pleased to be ready to go at 7:00am, I wheeled the bike out of the accommodation, swung on board and rolled forward. Fouling there again. Off came the mudguard and I was on my way (10 minutes later, no noise, with the rack and bag giving some protection from the rain the following day). An M+ tyre is wider than spec (mine was 30+mm wide at 90psi) and much deeper than others, because of the extra 4mm layer to prevent 'drawing pin' punctures.

 

[biggs682]

got a similar noise on a front wheel on a road bike , swapped wheel noise went

so checked old wheel all good and true , spokes tight , no bearing play , hub axle looks straight but still get a thump thump tyre is fine and has been swapped

 

[gasinayr]

If your rear wheel axle has a rubber dust cover at the left hand side. Check that it is not sticking, had that on my bike, did my head in trying to find noise. If it is some oil on cover sorts it

 

[Flying Dodo]

I'd buy a new bike. It's the only guaranteed way to get rid of those annoying little noises.

 

[Scoosh]

Is it a new(-ish) tyre ? Does it still have some of those little bits of rubber sticking out from the sides ? 1 or more could be nicking a brake block ...

Alternatively, (and try not to laugh - I have this on my hybrid bike ) is it your clothing rubbing as you pedal ? (though 3x per rev would tend to rule this out)

 

[dodgy]

I've had the exact same noise, at the time I put it down to 25mm tyres rubbing on my tight clearance frame, changed to 23mm and noise still there.

In the end I figured out it was rear wheel bearings a little dry, easy to fix on a Shimano wheel.

 

[palinurus]

Thanks for the suggestions- hope to have a crack at it at the weekend.

 

[palinurus]

I'd buy a new bike. It's the only guaranteed way to get rid of those annoying little noises.

I was thinking along these lines this morning.