Rear Hub issue?

[mgarl10024]

Hi,

I know this will be vague - just brainstorming.

For the last few hundred miles, I've noticed a metallic 'scraping' sound that I can't trace.
- It comes and goes
- When active, repeats about once/twice a second
- Seems towards the rear
- Seems related the wheel rotation (going faster makes it quicker)
- Seems louder during the first mile (could just be me noticing it more)
- The bike is otherwise working fine
- I don't think it is drive chain related. I've recently replaced the chain/cassette, and the noise stops when I stop pedaling.
- I don't think it is front wheel related, having just had the hub serviced (and the issue was there before that)
- I've recently had the back wheel rebuilt after snapping a few spokes so I reckon that the wheel is true and the tensions are good.

However, the annoying bit is that when I put the bike in the rack, I can't reproduce the noise. This makes me worried that I'll take it to the shop and they can't find it.

I'm running out of places to try. Is this classic rear hub failing symptoms? Scraping noise when load bearing?
Should I just leave it until it gets worse and more reproducible? - It doesn't massively bother me, but I'm a preventative fix sorta guy.

I know this is vague, but any thoughts welcome. Marin San Anselmo 2010 hybrid, heavy rider with panniers, about 6000 miles in total, with 3000 of them on that wheel and hub, if that helps.

MG

 

[Yellow Saddle]

Can we just confirm that the scrape goes faster with wheel rotation and not with crank rotation?

 

[mgarl10024]

Can we just confirm that the scrape goes faster with wheel rotation and not with crank rotation?

Thanks for the reply. Yep. If I stop pedalling (no crank rotation) the scrape doesn't stop. I can hear it when rolling.

Edit: Removing typo.

 

[Yellow Saddle]

Thanks for the reply. Yep. If I stop pedalling (no crank rotation) the scrape stops. I can hear it when rolling.

I'm sorry, I am still uncertain. What do you mean by you can hear it when you are rolling?

Does the scrape only occur when pedaling?

 

[mgarl10024]

Sorry. My mistake. I read it twice before posting too!
Should have been: If I stop pedalling (no crank rotation) the scrape doesn't stop. I can hear it when rolling.
Scrape occurs independent of pedalling.

 

[Yellow Saddle]

Sorry. My mistake. I read it twice before posting too!
Should have been: If I stop pedalling (no crank rotation) the scrape doesn't stop. I can hear it when rolling.
Scrape occurs independent of pedalling.

OK, that rules out what I was thinking. Sorry I couldn't help.

 

[davidphilips]

Sorry for perhaps silly reply but are you sure its not your rear brake rubbing could even be a bit of stone etc on a brake pad?

 

[Moodyman]

That bike looks like it's running an Alfine 8? If so, place your gear in the 4th and put your bike upside down. The two yellow markers should be lined up. See the attached picture. These are slightly out of alignment.

If yours are not lined up perfectly, they will still work, but the internal ratchets won't run smoothly and will eventually wear out. Use your gear cable barrel adjuster to align the dots.

 

[Tim Hall]

Given that it's once per rotation, I'd be checking things like brake blocks, mudguards and so on.

 

[iluvmybike]

Have had an issue in past with the place where the rim is joined becoming slightly raised and you can feel it 'bump' a tad when u brake

 

[mgarl10024]

Thanks for all the replies - very useful.

It is interesting that no-one suspects the hub - this is good news I guess.

Incidentally, my bike is this one: http://www.thebikelist.co.uk/images/models/Marin/2010/San-Anselmo-Deore_10/san-anselmo-deore.jpg with these specs http://www.thebikelist.co.uk/marin/san-anselmo-deore-2010. No posh hub gears, all derailleur.

Next time the bike is in the rack, I'll thoroughly check out the brakes and mudguards etc. - not something I would have thought of.

If I'm really struggling, I'll try that tape idea. When you're on the bike it is difficult to see what position the wheel is in, so I might have to rope the GF in. :-)

Thanks again for all your advice, especially to such a vague query!

 

[gbb]

I always trot this one out because it happened to me...so it's worth considering...
Have you a spoke protector, a pie plate fitted ? Make sure it's secure. My wife's bike developed a noise at the rear, unable to reproduce when not on the bike a regular squeak, maybe a scrape ànd it turned out the spoke protectorwas rubbing against the spokes under load and squeaking. Took ma ages to track it down.
I removed the spoke protector...noise gone.

Worth a look, unlikely...but a possibility.

 

[mikeymustard]

You say you've had some spokes replaced - have the spokey dokes been put back properly?
Really though, if it's only occurring under load one of your spokes might be touching something inappropriately