rear wheel, scraping noise every rotation

silva

Well-Known Member
Location
Belgium
This is plaguing me since beginning of the year.

It comes by itself, lasts weeks then it goes by itself. And some time later, it's suddenly back. Last occasion it ceased a couple months ago. Since yesterday it's back.
Before yesterday there wasn't an apparent reason for its start.
Yesterday after I came home without experiencing anything along the road also not when arriving back. Some half hour later when I unloaded the bicycle it almost felt over, I wondered but I didn't check at the time. But hours later, when deciding to put the bike inside, I noticed the rear tire was entirely flat. Punctured 1 cm out of the center by a 2 cm long flathead nail, that looked like new (no rust, not bent, alike a nailgun just shot a new one in).
After removal and check I replaced the inner tire.
First ride after, that hated noise was back.
In the past I stopped dozens times along the road to try to locate the cause, for no result.

- When putting the bike upside down, and spinning the wheel, nothing is heard so the contact that produces the noise must be caused under the weight of bicycle and rider.
- There is plenty clearance in all directions around the outer tire - nothing comes close enough.
- I've learnt how to tru the wheel sideways (I put folded paper between a brake pad and the rim) and perpendicular (if that's the right word) with as reference an english key held close against it and stabilized along the luggage frame. In the past and today I succeeded truing it like that, but despite spending half an hour today along the road to tru subsequently finer, when I jump on the bike and ride away the noise is just like I didn't spend that half an hour.
- Then I just took away the hydraulic brake pads completely with their mount, to root these out as cause, and indeed, the noise just stayed.
- Today my bicycle had a small but heavy load and I was able to walk while holding the bike and hear the noise so that I could look. The noise occurred at a certain wheel position that I now marked on the tire and rim. A close inspection (of tire, rim and spokes) around the ground contact at that position reveiled nothing. I checked all spokes but none broken and no noticable (feel) tension differences.
- I then decided to lower the tire pressure, but again no influence on noise.

So despite all the effort I'm still standing where I was.
Since there is just nothing close enough to the tire to contact it, even under load, it's like the scraping noise comes from the wheel not its tire. One idea is that a couple crossing and eachother touching spokes, move relative to eachother under the stress of load.
I just don't know, I'm guessing all the way.

The setup is a 62 mm tire (Schwalbe "super moto x" on a 22 mm rim.
Since it happens alot that I carry substantial weight, and I'm not a small person too, I have to put quite some high pressure, for this size, in the tire (I typically pump till 3.2 bar).

The surface of the outer tires (front and back) shows quite some sideways movement. Hard to get rid of it, possibly due to the fairly narrow rim for the tire. But that's since I acquired the bike 2 years ago, and the noise wasn't present then.

So I'm now hunting reasons I didn't think of.
 
OP
silva

silva

Well-Known Member
Location
Belgium
Just thought of a test to rout out spokes scraping at their crossing, I could put some rubber there inbetween, if the noise sounds different or is gone it would further narrow down to a first cause.
 

ColinJ

Puzzle game developer
I was going to suggest lack of tyre clearance, but that seems to have been ruled out.

I had that problem on one bike. Front tyre clearance was very tight, but the wheel span freely with the bike on a stand. The bike had a steel fork, and with my weight on the bike it bent just enough for the tyre to rub.
 

Pat "5mph"

A kilogrammicaly challenged woman
Moderator
Location
Glasgow
Hub bearings need serviced or maybe a new wheel if they are goosed.
I have much experience in rear wheel noises, having killed several rear wheels by ignoring such noises :whistle:
Best one was when the rear bearings fell out after a mighty crunch noise :smile:
Yes, it can look like the tyre is moving sideways, it's actually the wheel axle that is moving sideways.
 

Sharky

Guru
Location
Kent
Also check the rear triangle. An old frame of mine rusted through and allowed the frame to flex a lot.
 
OP
silva

silva

Well-Known Member
Location
Belgium
I have had 3 periods of several weeks so far this year after which the noise near-suddenly disappeared.
Yesterday morning it restarted after having replaced an inner tube.
That's why yesterday afternoon, driven mad by hours that noise when cycling and ppl looking behind, and after spending half an hour at the spokes tension and balance, lowered the pressure to see if that had effect. Because the noise went by itself before, a thought was that the gradual drop over time of tire pressure could have been an explanation.
Since it goes by itself after some time, doesn't that eliminate bearings?
It's an aluminium frame so rust is not applicable here, and it's a fixed gear, so no freewheel so freehub can't be a cause.
Another thought: could a nipple fret out its hole in the rim, and "rattle" around in it?
Because the noise is very specific, as I found out yesterday and said above: I marked the rim and tire there, everytime the wheel rotates into that position, and under a certain minimum load, the noise occurs.
Above that load, no matter how much more, the noise doesn't change.
For ex, when I left I heard the noise as loud as when I returned, but at the return I had a 15 kilo workbench grinder mounted on my transport rack just behind the saddle.
And I had have much heavier loads, with this same wheel ex 55 kilo (most of 4 disassembled store racks of 18 kilo, my bicycles weight including me probably total 160) together, rack, bags, along tube and on a backpack, 25 km trip, and no noise.

The hub is a Surly Ultra singlespeed disc 135x10mm 36G (36 spokes).
The brakes are Magura hydraulic pressured pads on the rim walls.
The rim is a dutch brand Ryde model Yura22.
The rear cog is mounted on the hub with 4mm spacers between to correct the 5 mm wrong chainline that the bike was delivered with, mounted with 6 steel (grade 12.9) 20 mm (too long, should be 16, but doesn't harm, well oiled) bolts.

First I'm gonna try is to put rubber between the crossings of the spokes nearby the position where the noise comes from.
 
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OP
silva

silva

Well-Known Member
Location
Belgium
The rubber between the spokes crossing and a test ride made clear no difference.
BUT maybe some progress: when I looked for the marked place to put the rubber, I noticed that my markings of tire and rim weren't on the same line with the axle anymore. They had shifted 1 cm away from eachother.
I decided to deflate the tire and I saw the markings move a couple mm back towards eachother and I heard a few clicks, no scraping noise still some noise.
I re-inflated the tire and the markings moved again that couple mm away from eachother.
So apparently, my outer tire is moving relative and parallel to the rim.
Now is this normal? It could have been the case all the time, since without markings it isn't indicated.
Another element: maybe the 22 mm rim doesn't have much reserve design strength with such 62 mm tires. There aren't many people that frequently carry lotsa weight and require a relative high tire pressure to not have the tire deform too much.
Schwalbe's super moto x tires are specified at pressure range 2-4 bar and I put them at 3.2 (if my gauge is correct - I also check manually by pulling with both hands on the tire and it should bend sideways about 3 mm.

Since the tire has been deflated reinflated, maybe it settled now better than the first time after the flat, I'll do a ride and see if that has influence on the noise.

See, I heard mechanical clicks at the spokes when I deflated the tire, it does look like the tire pressure has some impact on the spokes / wheel shape. The scraping noise could be due to wheel deformation which in turn could have been due to the tire not have seated well, also explaining the sudden revival of the noise after a punctured tire and replacement.
 
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OP
silva

silva

Well-Known Member
Location
Belgium
Errr, why not check out the hub bearings like four posters above have suggested.

Set about eliminating causes rather than expanding the list of possible causes ad infinitum.
But if bearings are "goosed", and that be the noise cause, why would the noise go away after some time?
 
OP
silva

silva

Well-Known Member
Location
Belgium
Hub bearings need serviced or maybe a new wheel if they are goosed.
I have much experience in rear wheel noises, having killed several rear wheels by ignoring such noises :whistle:
Best one was when the rear bearings fell out after a mighty crunch noise :smile:
Yes, it can look like the tyre is moving sideways, it's actually the wheel axle that is moving sideways.
Can a wheel wiggle without a variation to be noticed at the brake pads?
 
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