problem with rear wheel

Following on from Adam Lea's message. . .

Quoted message said:

I have had a problem with my mountain bike in that the rear brake pads keep
rubbing on the wheel rim and no amount of adjustment seemed to prevent this.
On closer inspection I have noticed that when I disconnect the rear brake
and spin the wheel it appears to be slightly buckled. All the spokes are
still solidly attached. This might sound a really silly question but if I
leave the rear brake disconnected will it be safe to ride until the weekend
when I can get the LBS to have a look at it or would it be best to leave it
alone? Is it possible for a wheel to catastrophically fail on a ride?

As I expect you know, the magic of spokes happens because they are
_always in tension_. If you find any of the spokes are not 'pulling
their weight' then that's a bad sign and of course fails the 'always in
tension' rule.

If a spoke goes 'thud' instead of 'ping' when you hit it with say a
screwdriver then that tells you all you need to know. You may have a
number going 'thud' in which case tighten them up and see what happens
(you have nothing to lose). I learned how to true a wheel with a pair
of pliers (on the spoke nuts) by a bit of trial and error with the bike
in the frame and seeing how a tweak here and twist there would affect
the space between the brake blocks.

As for "is it safe to ride" the answer is
(a) Not if there is more than one slack spoke
(b) Probably otherwise for a bit providing you don't bash it around and
you're not overloading it in any other way.

Bike wheels can be in an awful state and still be ridden but (a) I
wouldn't and (b) it probably does more and irreparable damage.

(I am not a cycle mechanic.)

--
PETER FOX Not the same since the bra business went bust
[email hidden]
www.eminent.demon.co.uk - Lots for cyclists

In article <[email hidden]>
Peter Fox <[email hidden]> wrote:
<snip>

Quoted message said:

If a spoke goes 'thud' instead of 'ping' when you hit it with say a
screwdriver then that tells you all you need to know. You may have a
number going 'thud' in which case tighten them up and see what happens
(you have nothing to lose).

Except putting the wheel so badly out of true that it's totally
unusable.

Quoted message said:

I learned how to true a wheel with a pair
of pliers (on the spoke nuts)

They're called nipples. Using anything other than a proper good-quality
spoke wrench stands a good chance of damaging them, making it much
harder to fix the wheel.

Quoted message said:

by a bit of trial and error with the bike
in the frame and seeing how a tweak here and twist there would affect
the space between the brake blocks.

As for "is it safe to ride" the answer is
(a) Not if there is more than one slack spoke
(b) Probably otherwise for a bit providing you don't bash it around and
you're not overloading it in any other way.

Bike wheels can be in an awful state and still be ridden but (a) I
wouldn't and (b) it probably does more and irreparable damage.

Wheels rarely fail catastrophically except in a crash or with severe
overloading - it's perfectly possible that a wheel with several spokes
missing will continue to keep the bike off the ground until a reapir can
be effected. A totally pretzeled wheel can be made usable by jumping on
it - the spoke tension will probably be all over the place but it will
get you home without a problem if you slacken the brakes a bit.

Quoted message said:

(I am not a cycle mechanic.)

I was.

In article <[email hidden]>

Adam Lea said:

I have had a problem with my mountain bike in that the rear brake pads keep
rubbing on the wheel rim and no amount of adjustment seemed to prevent this.

What sort of brakes, what sort of rim?

Quoted message said:

On closer inspection I have noticed that when I disconnect the rear brake
and spin the wheel it appears to be slightly buckled.

Up & down or side to side?

Quoted message said:

All the spokes are
still solidly attached. This might sound a really silly question but if I
leave the rear brake disconnected will it be safe to ride until the weekend
when I can get the LBS to have a look at it

Can you not slacken the cable so the brake still has some effect without
rubbing too much? The back brake doesn't do a lot of work anyway, so
you can probably get away without if you're sensible, but without two
brakes the bike is illegal so you could be liable in the case of an
accident. If it was a car with wobbly wheels and defective brakes would
you even be asking a question like this?

Quoted message said:

or would it be best to leave it
alone? Is it possible for a wheel to catastrophically fail on a ride?

If you hit something hard enough, or try to carry too large a load, then
a wheel can just crumple into the ground. It's not very likely though.
What is more likely is that the uneven spoke tension will cause other
spokes to fail, to the point that the wheel becomes so floppy or rubs so
much that you end up carrying the bike.

Peter Fox wrote on 29/11/2006 00:50 +0100:

Quoted message said:

(I am not a cycle mechanic.)

And it shows. I add this as a note to future readers not to follow the
advice offered. It will make a mess of your wheel and of your spoke
nipples.

--
Tony

"...has many omissions and contains much that is apocryphal, or at least
wildly inaccurate..."
Douglas Adams; The Hitchhiker's Guide to the Galaxy

Adam Lea wrote on 29/11/2006 00:16 +0100:

Quoted message said:

I have had a problem with my mountain bike in that the rear brake pads keep
rubbing on the wheel rim and no amount of adjustment seemed to prevent this.
On closer inspection I have noticed that when I disconnect the rear brake
and spin the wheel it appears to be slightly buckled. All the spokes are
still solidly attached. This might sound a really silly question but if I
leave the rear brake disconnected will it be safe to ride until the weekend
when I can get the LBS to have a look at it or would it be best to leave it
alone? Is it possible for a wheel to catastrophically fail on a ride?

You should be fine till the weekend, especially if you follow Sheldon
Brown's advice about braking (http://sheldonbrown.com/brakturn.html)

At the weekend you can either give it to a bike shop or get a spoke key
and DIY. It's pretty simple once you understand the principles of
truing and you can use your upturned bike and the brake blocks as a
truing stand. Helpfully Sheldon has also provided instructions for that
too: http://sheldonbrown.com/wheelbuild.html

--
Tony

"...has many omissions and contains much that is apocryphal, or at least
wildly inaccurate..."
Douglas Adams; The Hitchhiker's Guide to the Galaxy

"Rob Morley" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

In article <[email hidden]>

Adam Lea said:

I have had a problem with my mountain bike in that the rear brake pads
keep
rubbing on the wheel rim and no amount of adjustment seemed to prevent
this.

What sort of brakes, what sort of rim?

V brakes, not sure of the type of rim.

Quoted message said:

Quoted message said:

On closer inspection I have noticed that when I disconnect the rear brake
and spin the wheel it appears to be slightly buckled.

Up & down or side to side?

Side to side

Quoted message said:

Quoted message said:

All the spokes are
still solidly attached. This might sound a really silly question but if I
leave the rear brake disconnected will it be safe to ride until the
weekend
when I can get the LBS to have a look at it

Can you not slacken the cable so the brake still has some effect without
rubbing too much? The back brake doesn't do a lot of work anyway, so
you can probably get away without if you're sensible, but without two
brakes the bike is illegal so you could be liable in the case of an
accident. If it was a car with wobbly wheels and defective brakes would
you even be asking a question like this?

I know it is not desirable - that is why I was wondering if I could get away
with it for a couple of days until I could get it fixed. I wasn't planning
to ride it like this all the time.

Quoted message said:

Quoted message said:

or would it be best to leave it
alone? Is it possible for a wheel to catastrophically fail on a ride?

If you hit something hard enough, or try to carry too large a load, then
a wheel can just crumple into the ground. It's not very likely though.
What is more likely is that the uneven spoke tension will cause other
spokes to fail, to the point that the wheel becomes so floppy or rubs so
much that you end up carrying the bike.

This is what I am worried about. I have a feeling that the damage occurred
from hitting a pothole somewhere so another impact could really mess it up.
On reflection I will drive to work this week and get the LBS to have a look
at it on Saturday morning.

Adam Lea wrote on 29/11/2006 08:30 +0100:

Quoted message said:

This is what I am worried about. I have a feeling that the damage occurred
from hitting a pothole somewhere so another impact could really mess it up.
On reflection I will drive to work this week and get the LBS to have a look
at it on Saturday morning.

Shocks and loads on a wheel only serve to reduce the spoke tension
temporarily, not increase it by anything significant.

--
Tony

"...has many omissions and contains much that is apocryphal, or at least
wildly inaccurate..."
Douglas Adams; The Hitchhiker's Guide to the Galaxy

Adam Lea said:

"Rob Morley" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

In article <[email hidden]>

Adam Lea said:

I have had a problem with my mountain bike in that the rear brake pads
keep
rubbing on the wheel rim and no amount of adjustment seemed to prevent
this.

What sort of brakes, what sort of rim?

V brakes, not sure of the type of rim.

V brakes tend to sit the pads very close to the rim, so it might not be out
by that far. The wheel could still be strong enough.

How many spokes are there? If it is a traditional 36 spoke wheel, having one
broken isn't all that big a deal. If it is a modern low spoke count wheel,
I wouldn't feel safe riding it.

Quoted message said:

Quoted message said:

Quoted message said:

On closer inspection I have noticed that when I disconnect the rear
brake and spin the wheel it appears to be slightly buckled.

Up & down or side to side?

Side to side

About how many mm does the rim move side to side when spun?

As others have said, this is basic work to fix at your local shop, IME all
wheels have to be trued at some point. I think the last time I had this
done it cost about £8.

I would just ride it for now unless it is really far out, low spoke count or
you are particularly heavy (not wanting to get personal...)

--
Jim

in message <[email hidden]>, Adam Lea

(') said:

I have had a problem with my mountain bike in that the rear brake pads
keep rubbing on the wheel rim and no amount of adjustment seemed to
prevent this. On closer inspection I have noticed that when I disconnect
the rear brake and spin the wheel it appears to be slightly buckled. All
the spokes are still solidly attached. This might sound a really silly
question but if I leave the rear brake disconnected will it be safe to
ride until the weekend when I can get the LBS to have a look at it or
would it be best to leave it alone? Is it possible for a wheel to
catastrophically fail on a ride?

A slight buckle isn't going to cause the wheel to fail catastrophically,
and, indeed, really catastrophic failures as a result of buckling are not
common.

I would not leave the rear brake disconnected, though.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; Let's have a moment of silence for all those Americans who are stuck
;; in traffic on their way to the gym to ride the stationary bicycle.
;; Rep. Earl Blumenauer (Dem, OR)

in message <[email hidden]>, Peter Fox

(') said:

As for "is it safe to ride" the answer is
(a) Not if there is more than one slack spoke

A 36 spoke wheel is perfectly safe to ride with up to half a dozen *broken*
spokes, provided they aren't adjacent to one another. There's massive
redundancy in a traditional bicycle wheel.

Quoted message said:

(b) Probably otherwise for a bit providing you don't bash it around and
you're not overloading it in any other way.

Bike wheels can be in an awful state and still be ridden but (a) I
wouldn't and (b) it probably does more and irreparable damage.

It may do more damage but not quickly and, until the rim actually pringles,
none of it irreparable.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
Das Internet is nicht fuer gefingerclicken und giffengrabben... Ist
nicht fuer gewerken bei das dumpkopfen. Das mausklicken sichtseeren
keepen das bandwit-spewin hans in das pockets muss; relaxen und
watchen das cursorblinken. -- quoted from the jargon file

Tony Raven said:

At the weekend you can either give it to a bike shop or get a spoke key
and DIY. It's pretty simple once you understand the principles of
truing and you can use your upturned bike and the brake blocks as a
truing stand.

If you decide to DIY:
- Take the broken spoke to the shoppy or at least measure it so you can
get a new one the same length
- Get a few more spares while you're there so if more go ping while
you're trying to sort out the tension or you round off the nipples you
don't have to go back to the shoppy again
- If it is old you might want to change the rim tape too
- Sods law (and maybe some engineering) says that when spokes break on
the rear wheel it will be on the drive side and you'll have to take the
gear cassette off to thread the new spoke in. You need some more tools
for this and maybe a big hammer
- Allow plenty of time for the job

In article <[email hidden]>

Adam Lea said:

"Rob Morley" <[email hidden]> wrote in message
news:[email hidden]...

<snip>

Quoted message said:

Quoted message said:

If you hit something hard enough, or try to carry too large a load, then
a wheel can just crumple into the ground. It's not very likely though.
What is more likely is that the uneven spoke tension will cause other
spokes to fail, to the point that the wheel becomes so floppy or rubs so
much that you end up carrying the bike.

This is what I am worried about. I have a feeling that the damage occurred
from hitting a pothole somewhere so another impact could really mess it up.
On reflection I will drive to work this week and get the LBS to have a look
at it on Saturday morning.

From another of your posts it seems you have a single broken spoke - you
should be able to slightly slacken the spoke on each side of the broken
one to remove most of the kink, and the wheel will remain usable until
the weekend. If you don't have a spoke wrench to do this you can
probably get away with using a small adjustable spanner (make sure it's
really snug on the nipple) - it's generally easier to loosen spokes than
to tighten them, and the worst that's going to happen if you damage the
nipples is you'll need to replace them along with the broken spoke.

Simon Brooke said:

in message said:

As for "is it safe to ride" the answer is
(a) Not if there is more than one slack spoke

A 36 spoke wheel is perfectly safe to ride with up to half a dozen *broken*
spokes, provided they aren't adjacent to one another. There's massive
redundancy in a traditional bicycle wheel.

It well might be possible to cut half a dozen spokes from a well built
36 spoke wheel without problems, but the chances of breaking that many
spokes independently in normal on road use while the adjacent ones are
all properly tightened are pretty miniscule.

"Jim Higson" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

About how many mm does the rim move side to side when spun?

about 2-3mm.