Name that noise

I own a 2003 Trek 5200 ... pretty much stock bike (except Thomas seat post).
Recently, when peddling - I get a knock. The knock occurs when my right
pedal is on the down stroke and left is almost to the top of the stroke.
Typically I can just feel the knock - but sometimes you can hear it. It
seems to happen at different frequency depending on the gear I'm in.

My LBS has not proven to be the best - so if I can help direct them - I'd
love to do so.

Any thoughts, opinions, pointers, etc - would be greatly appreciated.

BBB

snippage of booner's q: re knock

Different frequency relative to pedaling rpm depending on gear noise
is in crank/bb. I am assuming that is what you meant when you wrote 'It
seems to happen at different frequency depending on the gear I'm in'.
If not, ignore the rest of this.

I will suggest a rear spoke issue (non-drive side to be specific).
You have a number of loose spokes surrounding one tighter one that gets
sharply loaded when the forces are properly aligned. This is the
scenario I envision: on your right down stroke you load the wheel
laterally, stressing the drive side spokes and slackening the non-drive
side spokes. Upon reaching the bottom of your stroke, there is a rapid
unloading of the drive side and a corresponding loading of the
non-drive side. This one spoke, because it is tighter than the
surrounding spokes, takes the majority of this load and this
"instantaneous" loading is causing the knock.

The frequency changes because of the phase-relationship between the
position of the spokes and the pedals. When they frequency of the
pedal stroke is the same or close to a factor of the frequency of that
single spoke being at the bottom of it's cycle, the noise will occur
more frequently. If they are out of phase (different gear than
before), then you will have just a few instances.

Check it out - give the non-drive side spokes a squeeze and if one is
significantly tighter than all the rest, that's your culprit (maybe).
If you can't find any there, check your front wheel (again, non-drive
side) and finally, if still no luck, drip some lube into each spoke
hole and stress relieve the spokes.

HTH

D'ohBoy

OOPS!

Please read this rather than my earlier post - should have been drive
side spokes that were making the noise:

Different frequency relative to pedaling rpm depending on gear noise
is in crank/bb. I am assuming that is what you meant when you wrote 'It
seems to happen at different frequency depending on the gear I'm in'.
If not, ignore the rest of this.

I will suggest a rear spoke issue (drive side to be specific).
You have a number of loose spokes surrounding one tighter
one that gets sharply loaded when the forces are properly aligned.

This is the scenario I envision: on your right down stroke you load
the wheel laterally (at the bottom, I believe the whole wheel is
actually in torsion around the hub), stressing the non-drive side
bottom spokes and slackening the driveside spokes. Upon
reaching the bottom of your stroke, there is a rapid unloading of the
non-drive side and a corresponding loading of the drive side. This
one spoke, because it is tighter than thesurrounding spokes, takes
the majority of this load and this "instantaneous" loading is causing
the knock.

The frequency changes because of the phase-relationship between the
position of the spokes and the pedals. When they frequency of the
pedal stroke is the same or close to a factor of the frequency of that
single spoke being at the bottom of it's cycle, the noise will occur
more frequently. If they are out of phase (different gear than
before), then you will have just a few instances.

Check it out - give the drive side spokes a squeeze and if one is
significantly tighter than all the rest, that's your culprit (maybe).
If you can't find any there, check your front wheel (again, drive
side) and finally, if still no luck, drip some lube into each spoke
hole and stress relieve the spokes.

HTH

"D'ohBoy" wrote: )clip) You have a number of loose spokes surrounding one
tighter one that gets sharply loaded when the forces are properly aligned.
(clip)
^^^^^^^^^^^^^^^
It sound to me like the OP was saying that the knock occurs on every pedal
revolution, just as the load is transferring from the right to the left
side. This would HAVE to be related to the crank, not the rear wheel. I
figure the relationship to the gears has to do with the fact that the crank
torque changes with gear changes.

If it depended on the phasing of the rear wheel to the crank somehow, then
it would not occur on every pecal stroke.

booner wrote:
I own a 2003 Trek 5200 ... pretty much stock bike (except Thomas seat post).
Recently, when peddling - I get a knock. The knock occurs when my right
pedal is on the down stroke and left is almost to the top of the stroke.
Typically I can just feel the knock - but sometimes you can hear it. It
seems to happen at different frequency depending on the gear I'm in.

My LBS has not proven to be the best - so if I can help direct them - I'd
love to do so.

Any thoughts, opinions, pointers, etc - would be greatly appreciated.

BBB

This sure sounds like a BB or crank related problem to me. Forgive me
for asking, but have you checked to make sure everything is tight?

Josh

booner wrote:
I own a 2003 Trek 5200 ... pretty much stock bike (except Thomas seat post).
Recently, when peddling - I get a knock. The knock occurs when my right
pedal is on the down stroke and left is almost to the top of the stroke.
Typically I can just feel the knock - but sometimes you can hear it. It
seems to happen at different frequency depending on the gear I'm in.

My LBS has not proven to be the best - so if I can help direct them - I'd
love to do so.

Any thoughts, opinions, pointers, etc - would be greatly appreciated.


I've had this happen, in my case remounting the cranks (square taper)
with a torque wrench was the cure.

-nate

On Fri, 14 Apr 2006 13:25:28 GMT, "booner" wrote:

I own a 2003 Trek 5200 ... pretty much stock bike (except Thomas seat post).
Recently, when peddling - I get a knock. The knock occurs when my right
pedal is on the down stroke and left is almost to the top of the stroke.
Typically I can just feel the knock - but sometimes you can hear it. It
seems to happen at different frequency depending on the gear I'm in.

My LBS has not proven to be the best - so if I can help direct them - I'd
love to do so.

Any thoughts, opinions, pointers, etc - would be greatly appreciated.

Octalink BB? If so, the crank is probably wallowing the splines.
Sometimes, retorquing the bolts will stop the noise for a mile or two,
but it's going to come right back if that's what has happened. As a
temporary fix, you can remove the left crank, douse the splines with
red Loctite, reassemble, and plan on replacing the cranks and BB (with
something *other* than Octalink) fairly soon. The Loctite may buy you
a little extra time to shop for a deal.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

I'm not much of a mechanic .. just ride it (other than cleaning the chain,
cleaning it up, etc) ... what is everything?

"Josh Hassol" wrote in message
ups.com...

booner wrote:
I own a 2003 Trek 5200 ... pretty much stock bike (except Thomas seat
post).
Recently, when peddling - I get a knock. The knock occurs when my right
pedal is on the down stroke and left is almost to the top of the stroke.
Typically I can just feel the knock - but sometimes you can hear it. It
seems to happen at different frequency depending on the gear I'm in.

My LBS has not proven to be the best - so if I can help direct them -
I'd
love to do so.

Any thoughts, opinions, pointers, etc - would be greatly appreciated.

BBB

This sure sounds like a BB or crank related problem to me. Forgive me
for asking, but have you checked to make sure everything is tight?

Josh

That could be it. When I get out of the saddle and apply some force - I get
a ping from my real wheel occasionally. Last year, took it to the shop -
they applied some lube of some sort - went away for a while - then came
back.

The noise does seem to be in the pedal/crank/bb area. I have some other
wheels. I guess for data sake - I could switch them out and see what
happens with the mysterious noise.

Just called the LBS - the can't even look at it for over a week.

"D'ohBoy" wrote in message
ups.com...
OOPS!

Please read this rather than my earlier post - should have been drive
side spokes that were making the noise:

Different frequency relative to pedaling rpm depending on gear noise
is in crank/bb. I am assuming that is what you meant when you wrote 'It
seems to happen at different frequency depending on the gear I'm in'.
If not, ignore the rest of this.

I will suggest a rear spoke issue (drive side to be specific).
You have a number of loose spokes surrounding one tighter
one that gets sharply loaded when the forces are properly aligned.

This is the scenario I envision: on your right down stroke you load
the wheel laterally (at the bottom, I believe the whole wheel is
actually in torsion around the hub), stressing the non-drive side
bottom spokes and slackening the driveside spokes. Upon
reaching the bottom of your stroke, there is a rapid unloading of the
non-drive side and a corresponding loading of the drive side. This
one spoke, because it is tighter than thesurrounding spokes, takes
the majority of this load and this "instantaneous" loading is causing
the knock.

The frequency changes because of the phase-relationship between the
position of the spokes and the pedals. When they frequency of the
pedal stroke is the same or close to a factor of the frequency of that
single spoke being at the bottom of it's cycle, the noise will occur
more frequently. If they are out of phase (different gear than
before), then you will have just a few instances.

Check it out - give the drive side spokes a squeeze and if one is
significantly tighter than all the rest, that's your culprit (maybe).
If you can't find any there, check your front wheel (again, drive
side) and finally, if still no luck, drip some lube into each spoke
hole and stress relieve the spokes.

HTH

In article cpN%f.97814$oL.97277@attbi_s71, "booner"
wrote:

I own a 2003 Trek 5200 ... pretty much stock bike (except Thomas seat post).
Recently, when peddling - I get a knock. The knock occurs when my right
pedal is on the down stroke and left is almost to the top of the stroke.
Typically I can just feel the knock - but sometimes you can hear it. It
seems to happen at different frequency depending on the gear I'm in.

My LBS has not proven to be the best - so if I can help direct them - I'd
love to do so.

Any thoughts, opinions, pointers, etc - would be greatly appreciated.

how 'bout a problem with your shoe/cleat or cleat/pedal interface?
(assuming you're using them.) a worn or loose cleat can make a nice
'klonk'.

have you checked your anklebone for bruising and bleeding? (just
kidding with that one. sorry.)