Rear bearing 'hum' on corners. Cause?



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T

Thomas Burns

Guest
I recently picked up a Trek 820 for a song that needed only a moderate amount of work to get into
shape, and the only outstanding issue (besides a frustratingly persistent front brake squeal!) is a
prominent humming of the rear wheel when cornering. I suspect it's the bearings, and would like
input on whether all they need is a clean and repack, or is this a sign of more extensive wear and I
should replace the bearings, cones, etc? There is a slight amount of play in the wheel, so it does
need a cone adjustment. When riding on straightaways, there is no noticeable noise at all from the
bearings - only when cornering.

t
--
Thomas Burns thrshr @@ hotmail
 
A

A Muzi

Guest
"Thomas Burns" <[email protected]> wrote in message
news:[email protected]...
> I recently picked up a Trek 820 for a song that needed only a moderate amount of work to get into
> shape, and the only outstanding issue (besides
a
> frustratingly persistent front brake squeal!) is a prominent humming of
the
> rear wheel when cornering. I suspect it's the bearings, and would like input on whether all they
> need is a clean and repack, or is this a sign of more extensive wear and I should replace the
> bearings, cones, etc? There
is
> a slight amount of play in the wheel, so it does need a cone adjustment. When riding on
> straightaways, there is no noticeable noise at all from the bearings - only when cornering.
>
> t
> --

Remove the wheel and see if it's a broken axle - sounds like that.

--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971
 
G

G Huang

Guest
Thomas Burns wrote:
> I recently picked up a Trek 820 for a song that needed only a moderate amount of work to get into
> shape, and the only outstanding issue (besides a frustratingly persistent front brake squeal!) is
> a prominent humming of the rear wheel when cornering. I suspect it's the bearings, and would like
> input on whether all they need is a clean and repack, or is this a sign of more extensive wear and
> I should replace the bearings, cones, etc? There is a slight amount of play in the wheel, so it
> does need a cone adjustment. When riding on straightaways, there is no noticeable noise at all
> from the bearings - only when cornering.

Could it be that the tire is more knobby on the sides than the center?

GH
 
T

Thomas Burns

Guest
"G Huang" <[email protected]_bell-labs.com> wrote in message
news:[email protected]_bell-labs.com...
>
> Thomas Burns wrote:
> > I recently picked up a Trek 820 for a song that needed only a moderate amount of work to get
> > into shape, and the only outstanding issue
(besides a
> > frustratingly persistent front brake squeal!) is a prominent humming of
the
> > rear wheel when cornering. I suspect it's the bearings, and would like input on whether all they
> > need is a clean and repack, or is this a sign
of
> > more extensive wear and I should replace the bearings, cones, etc?
There is
> > a slight amount of play in the wheel, so it does need a cone adjustment. When riding on
> > straightaways, there is no noticeable noise at all from
the
> > bearings - only when cornering.
>
> Could it be that the tire is more knobby on the sides than the center?

I don't think this is it, though it's an option that never crossed my mind. The hum is a definite
hum that increases the tighter the turn, rather than the more rumbly road noise you get from the
tire. An excellent low-tech suggestion, though.

t
 
T

Thomas Burns

Guest
"A Muzi" <[email protected]> wrote in message news:[email protected]...
> "Thomas Burns" <[email protected]> wrote in message
> news:[email protected]...
> > I recently picked up a Trek 820 for a song that needed only a moderate amount of work to get
> > into shape, and the only outstanding issue
(besides
> a
> > frustratingly persistent front brake squeal!) is a prominent humming of
> the
> > rear wheel when cornering. I suspect it's the bearings, and would like input on whether all they
> > need is a clean and repack, or is this a sign
of
> > more extensive wear and I should replace the bearings, cones, etc?
There
> is
> > a slight amount of play in the wheel, so it does need a cone adjustment. When riding on
> > straightaways, there is no noticeable noise at all from
the
> > bearings - only when cornering.
> >
> > t
> > --
>
> Remove the wheel and see if it's a broken axle - sounds like that.

This makes sense. I planned on pulling it all apart in any case, but since I'm in the process of
rebuilding a bike for one of my other sons I was going to put this off until later. But if the axle
is broken I should probably do that one first (or keep it off limits). I already adjusted the cones
to remove some play in the wheel, and after a brief ride some play reappeared. I originally thought
it was my novice skills, but something tells me a broken axle might behave this way also.

t
 
R

Robin Hubert

Guest
"Thomas Burns" <[email protected]> wrote in message
news:[email protected]...
>
> "A Muzi" <[email protected]> wrote in message news:[email protected]...
> > "Thomas Burns" <[email protected]> wrote in message
> > news:[email protected]...
> > > I recently picked up a Trek 820 for a song that needed only a moderate amount of work to get
> > > into shape, and the only outstanding issue
> (besides
> > a
> > > frustratingly persistent front brake squeal!) is a prominent humming
of
> > the
> > > rear wheel when cornering. I suspect it's the bearings, and would
like
> > > input on whether all they need is a clean and repack, or is this a
sign
> of
> > > more extensive wear and I should replace the bearings, cones, etc?
> There
> > is
> > > a slight amount of play in the wheel, so it does need a cone
adjustment.
> > > When riding on straightaways, there is no noticeable noise at all from
> the
> > > bearings - only when cornering.
> > >
> > > t
> > > --
> >
> > Remove the wheel and see if it's a broken axle - sounds like that.
>
> This makes sense. I planned on pulling it all apart in any case, but
since
> I'm in the process of rebuilding a bike for one of my other sons I was
going
> to put this off until later. But if the axle is broken I should probably
do
> that one first (or keep it off limits). I already adjusted the cones to remove some play in the
> wheel, and after a brief ride some play
reappeared.
> I originally thought it was my novice skills, but something tells me a broken axle might behave
> this way also.
>

Yeah, but you couldn't have adjusted your cones if the axle is broken.

--
Robin Hubert <[email protected]
 
J

Jim Adney

Guest
On 03 Jun 2003 20:53:37 GMT "Thomas Burns" <[email protected]> wrote:

>I recently picked up a Trek 820 for a song that needed only a moderate amount of work to get into
>shape, and the only outstanding issue (besides a frustratingly persistent front brake squeal!) is a
>prominent humming of the rear wheel when cornering. I suspect it's the bearings, and would like
>input on whether all they need is a clean and repack, or is this a sign of more extensive wear and
>I should replace the bearings, cones, etc? There is a slight amount of play in the wheel, so it
>does need a cone adjustment. When riding on straightaways, there is no noticeable noise at all from
>the bearings - only when cornering.

If there really is a noise that you can hear only while cornering, I suspect that it is coming from
the tires. It is likely that in leaning, you are rolling on an unworn part of the tread that has
slightly different contours.

The bearings don't get sideload when you corner. The lean that you do naturally keeps the forces
"straight down" for the wheels and bearings. The direction does not change significantly, but the
magnitude of the force does increase as the lean becomes more extreme. Still, it would be quite
unusual to actually be able hear noise from the bearings.

-
-----------------------------------------------
Jim Adney [email protected] Madison, WI 53711 USA
-----------------------------------------------
 
D

David Kunz

Guest
Jim Adney wrote:
> On 03 Jun 2003 20:53:37 GMT "Thomas Burns" <[email protected]> wrote:
>
>
>>I recently picked up a Trek 820 for a song that needed only a moderate amount of work to get into
>>shape, and the only outstanding issue (besides a frustratingly persistent front brake squeal!) is
>>a prominent humming of the rear wheel when cornering. I suspect it's the bearings, and would like
>>input on whether all they need is a clean and repack, or is this a sign of more extensive wear and
>>I should replace the bearings, cones, etc? There is a slight amount of play in the wheel, so it
>>does need a cone adjustment. When riding on straightaways, there is no noticeable noise at all
>>from the bearings - only when cornering.
>
>
> If there really is a noise that you can hear only while cornering, I suspect that it is coming
> from the tires. It is likely that in leaning, you are rolling on an unworn part of the tread that
> has slightly different contours.
>
> The bearings don't get sideload when you corner. The lean that you do naturally keeps the forces
> "straight down" for the wheels and bearings. The direction does not change significantly, but the
> magnitude of the force does increase as the lean becomes more extreme. Still, it would be quite
> unusual to actually be able hear noise from the bearings.

I've had the flex of hard cornering cause disc rotors to slightly hit the pads and v-brakes to
slightly hit the rims. Could it be this?

David
 
C

Chris Zacho "Th

Guest
My tires make a different sound when I corner as well, and it does increase the harder I'm leaning.

Remember, when you round a corner the tires are not simply rolloing any more, there are shear forces
working on the rubber as well, and these could very likely affect their "song".

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": http://www.geocities.com/czcorner
 
N

Ns>

Guest
I know most Trek's have shimano on them, but I have had a problem after a major overhaul at a LBS
(tools were stolen:-( ) where Campy Record Road rear hub was built with identical bearings on each
side, but, the bearings are not supposed to be the same size... I got a new hub out of
it... But that could be the cause as well if you are using Campy hubs...

Also depending on the age of the bike, (if it has a freewheel) the Freewheel could need greasing
badly, if powering in and out of the corners hard it may make a gravelly (for lack of the right
word) sound.

My2c, NS
 
T

Thomas Burns

Guest
I wrote in message news:[email protected]...
> I recently picked up a Trek 820 for a song that needed only a moderate amount of work to get into
> shape, and the only outstanding issue (besides
a
> frustratingly persistent front brake squeal!) is a prominent humming of
the
> rear wheel when cornering. I suspect it's the bearings, and would like input on whether all they
> need is a clean and repack, or is this a sign of more extensive wear and I should replace the
> bearings, cones, etc?

First off, thanks to all for your various suggestions. I was on the verge of taking everything apart
when I went for one more test ride and found the problem to have an almost embarrasingly simple
cause. It turns out the vibrations from the knobbies on turns caused the reflector in the spokes to
also vibrate. The reflector had slid closer to the hub so that it was no longer held snugly by the
spokes. The reflector vibrated against the spokes, resulting in the hum that I was hearing (which
had a distinctly different tone from the hum of the tires).

Once I figured it out, I laughed and felt quite stooopid at the same time. At least it's one less
hub I need to overhaul.

t
 
C

Chris Zacho "Th

Guest
Glad you found the answer, and that it was something simple (read: harmless).

Do overhaul your hubs every now and then, though ;-3)

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": http://www.geocities.com/czcorner
 
D

David Kunz

Guest
Thomas Burns wrote:
> I wrote in message news:[email protected]...
>
>>I recently picked up a Trek 820 for a song that needed only a moderate amount of work to get into
>>shape, and the only outstanding issue (besides
>
> a
>
>>frustratingly persistent front brake squeal!) is a prominent humming of
>
> the
>
>>rear wheel when cornering. I suspect it's the bearings, and would like input on whether all they
>>need is a clean and repack, or is this a sign of more extensive wear and I should replace the
>>bearings, cones, etc?
>
>
> First off, thanks to all for your various suggestions. I was on the verge of taking everything
> apart when I went for one more test ride and found the problem to have an almost embarrasingly
> simple cause. It turns out the vibrations from the knobbies on turns caused the reflector in the
> spokes to also vibrate. The reflector had slid closer to the hub so that it was no longer held
> snugly by the spokes. The reflector vibrated against the spokes, resulting in the hum that I was
> hearing (which had a distinctly different tone from the hum of the tires).
>
> Once I figured it out, I laughed and felt quite stooopid at the same time. At least it's one less
> hub I need to overhaul.
>
> t
>
>

Believe it on not, I had the same thing happen -- I had just forgotten about it.

David
 
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