Front brake shuddering. Bad Wheels?

Greetings,

I am the happy owner of a new Trek 4300 bike. I haven't been on a bike
in 20 years and feel like a kid again. This is a great bike with one
concern.

Soon after arriving home the front brakes seemed to be losing traction
for part of the wheel's revolution. This caused a quick vibration to
the front wheel and forks. The more I rode the worse the shuddering.
After about 2 hours, the shuddering of the front end was so bad I had
to stop using the front brake.

I tried cleaning the rim. No help. I added a bit of toe-in to the
brakes (V type brakes). No help. I balanced the brakes. No help. I
carefully trued the rim to near perfection. No Help.

I finally went back to my LBS where I purchased the bike to see what
they thought. They said it seemed like the front wheel had a problem
with the machining on the side of the rim. Nothing I could detect
visually or by feel. They grabbed another 4300 out of stock and
swapped out the front wheel (WTB Dual Duty). Problem fixed. They said
they have had one other person with the same problem. To their credit,
they let me keep the front wheel of the other bike (leaving the other
bike un-sellable, till they get a new wheel for it).

I get the bike home and all feels well. Maybe just a touch of
vibration, maybe not. Hard to tell. As I ride more I can feel the
shuddering coming back. As of yesterday it was easily noticeable, but
the brakes are still functional. I suspect that the problem will
continue to get worse with use.

Anyone experience a wheel problem like this. Any homebrew fixes?
(Maybe lightly sandpapering the side of the rim???)

I plan on contacting my LBS again to discuss this with them. I would
also appreciate some advice or insight into this problem from the
group so I go in as an informed customer.

Thanks, Tracy

Pizza Man wrote:
Greetings,

I am the happy owner of a new Trek 4300 bike. I haven't been on a bike
in 20 years and feel like a kid again. This is a great bike with one
concern. {snip}

Already answered in AM-B.

Bill "hope they take care of you" S.

Forgive me, but answered where?


On Tue, 21 Sep 2004 17:55:37 GMT, "Bill Sornson"
wrote:

Pizza Man wrote:
Greetings,

I am the happy owner of a new Trek 4300 bike. I haven't been on a bike
in 20 years and feel like a kid again. This is a great bike with one
concern. {snip}

Already answered in AM-B.

Bill "hope they take care of you" S.

DaveH wrote: {top-post moved}
On Tue, 21 Sep 2004 17:55:37 GMT, "Bill Sornson"
wrote:
Pizza Man wrote:
Greetings,

I am the happy owner of a new Trek 4300 bike. I haven't been on a
bike in 20 years and feel like a kid again. This is a great bike
with one concern. {snip}

Already answered in AM-B.

Forgive me, but answered where?

Alt.mountain-bike

Bill "funny thing, for an alt group there's almost ZERO political BS in
there" S.

On Tue, 21 Sep 2004 20:37:03 -0400, DaveH
wrote:

Forgive me, but answered where?


On Tue, 21 Sep 2004 17:55:37 GMT, "Bill Sornson"
wrote:

Pizza Man wrote:
Greetings,

I am the happy owner of a new Trek 4300 bike. I haven't been on a bike
in 20 years and feel like a kid again. This is a great bike with one
concern. {snip}

Already answered in AM-B.

alt.mountain-bike
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

On 21 Sep 2004 08:51:50 -0700, (Pizza Man)
wrote:

Greetings,

I am the happy owner of a new Trek 4300 bike. I haven't been on a bike
in 20 years and feel like a kid again. This is a great bike with one
concern.

Soon after arriving home the front brakes seemed to be losing traction
for part of the wheel's revolution. This caused a quick vibration to
the front wheel and forks. The more I rode the worse the shuddering.
After about 2 hours, the shuddering of the front end was so bad I had
to stop using the front brake.

I tried cleaning the rim. No help. I added a bit of toe-in to the
brakes (V type brakes). No help. I balanced the brakes. No help. I
carefully trued the rim to near perfection. No Help.

From what's been done so far, I doubt that the problem is in the
wheel, though if it is, the lbs will probably know about the
issue...and likely won't have a problem with getting you a functional
replacement. Otherwise, I'd suggest that you try adjusting the brake
pad position to center the contact point on the braking surface of the
rim if that's not where it is already, and check to make sure that
neither of the V-brake arms has any significant slop at the pivot.
You may also find that swapping to a different brand of brake pad
fixes the problem. I've had noisy and shaky results with some Shimano
pads; swapping to the oft-mentioned Kool-Stop Salmon pads fixed it.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

On Wed, 22 Sep 2004 00:55:16 GMT, "Bill Sornson"
wrote:

DaveH wrote: {top-post moved}
On Tue, 21 Sep 2004 17:55:37 GMT, "Bill Sornson"
wrote:
Pizza Man wrote:
Greetings,

I am the happy owner of a new Trek 4300 bike. I haven't been on a
bike in 20 years and feel like a kid again. This is a great bike
with one concern. {snip}

Already answered in AM-B.

Forgive me, but answered where?

Alt.mountain-bike
I tried to figure it out. I really did.
Bill "funny thing, for an alt group there's almost ZERO political BS in
there" S.
That is refreshing.

From what's been done so far, I doubt that the problem is in the
wheel, though if it is, the lbs will probably know about the
issue...and likely won't have a problem with getting you a functional
replacement. Otherwise, I'd suggest that you try adjusting the brake
pad position to center the contact point on the braking surface of the
rim if that's not where it is already, and check to make sure that
neither of the V-brake arms has any significant slop at the pivot.
You may also find that swapping to a different brand of brake pad
fixes the problem. I've had noisy and shaky results with some Shimano
pads; swapping to the oft-mentioned Kool-Stop Salmon pads fixed it.


I had planned on trying new pads, but I don't want to just band-aid
over a problem. If it is a bad wheel, I want it replaced. If it is
just a poor combination to have this wheel with these particular brake
pads, then trying new pads is clearly simpler than trying a bunch of
wheels. Having an engineering background, I really like to understand
why something is happening.

I spent a lot of time yesterday making sure the brake pads were
properly aligned. I even tried additional toe-in with little if any
improvement. I used a 3M abrasive pad (gray) to scuff up the pads and
also ran them around the contact area on the rim, then cleaned both
again with rubbing alcohol. This seemed to provide a small amount of
improvement, but still has a noticeably wide range of gripping when
using the brakes lightly or moderately.

As a control I tested my wife's new Diamondback. The brake assembly
seems the same except color (Tektro). She has anodized alloy rims.
When feathering the brakes hers were much more even and consistent. I
plan on doing a wheel swap then riding both bikes for a while to see
if the problem migrates or not. I'll probably pick up some kool-stops
as a bit of a test as well.

I will give the brake arms closer scrutiny as you suggest. I'll post
the results of my testing.

Thanks for the input, Tracy

Pizza Man wrote:
Greetings,

I am the happy owner of a new Trek 4300 bike. I haven't been on a bike
in 20 years and feel like a kid again. This is a great bike with one
concern.

Soon after arriving home the front brakes seemed to be losing traction
for part of the wheel's revolution. This caused a quick vibration to
the front wheel and forks. The more I rode the worse the shuddering.
After about 2 hours, the shuddering of the front end was so bad I had
to stop using the front brake.

I tried cleaning the rim. No help. I added a bit of toe-in to the
brakes (V type brakes). No help. I balanced the brakes. No help. I
carefully trued the rim to near perfection. No Help.

I finally went back to my LBS where I purchased the bike to see what
they thought. They said it seemed like the front wheel had a problem
with the machining on the side of the rim. Nothing I could detect
visually or by feel. They grabbed another 4300 out of stock and
swapped out the front wheel (WTB Dual Duty). Problem fixed. They said
they have had one other person with the same problem. To their credit,
they let me keep the front wheel of the other bike (leaving the other
bike un-sellable, till they get a new wheel for it).

I get the bike home and all feels well. Maybe just a touch of
vibration, maybe not. Hard to tell. As I ride more I can feel the
shuddering coming back. As of yesterday it was easily noticeable, but
the brakes are still functional. I suspect that the problem will
continue to get worse with use.

Anyone experience a wheel problem like this. Any homebrew fixes?
(Maybe lightly sandpapering the side of the rim???)

I plan on contacting my LBS again to discuss this with them. I would
also appreciate some advice or insight into this problem from the
group so I go in as an informed customer.

If the wheel is out of round in the vertical plane, ie. it isn't
perfectly round, but has some dips and bumps in it, you will get all
kinds of vibrations on braking. On some rims it's worse than others.
The solution is to true the wheel so that it's perfectly round. Side to
side trueness doesn't effect this much.

Wheel woes update:

This morning I swapped the front wheels between my bike and my wife's
bike. First I rode my wife's bike, stock, to see how the brakes felt.
Good. After the swap there was a noticeable shudder while braking. Not
near as bad as the same wheel on my bike, but I could tell the braking
had changed. Gotta be a bad wheel.

Next I rode my bike with wife's wheel. Definitely improved, but a
small amount of grab-no grab noticeable when the brakes were applied.
Hmm, not as definitive a test as I would have hoped.

I now suspect my WTB wheel is bad and maybe the entry level Tektro
brakes/pads are not tolerant of inconsistent rims.

Next, I flipped the bike over and grabbed a small patch of crocus
cloth (very mild abrasive). I held the patch against the rim using
moderate pressure with my fingers. I used the front fork to brace my
arm to keep my hand very still. I then slowly turned the tire with my
free arm. I found that the crocus cloth would drag then release at a
few select spots on the rim (the side with the skewer lever). I spun
the wheel multiple times in both directions till the amount of grab
was fairly consistent all the way around the rim. I then cleaned the
rim multiple times with fresh paper towels and rubbing alcohol. Next,
I applied the same treatment to the opposite side of the rim (away
from the skewer lever). Whoa! Lots of slick spots. I could really feel
what the brakes were feeling (grab-no grab). I worked on this side of
the rim for a while, but didn't make much progress in the consistency
of the grip. I cleaned it thoroughly and tested. Not bad at first,
but the longer I rode, the worse it got. At medium speed going down
hill if I use the brakes to control my speed I get a nasty wheel
shudder. Not as bad as the first wheel on the bike, but no way
acceptable.

I called my LBS and talked the problem over with the head honcho. No
problem. Bring in the bike and they will swap out the wheel set for
some other brand of wheel (It would likely be something they have in
stock, probably a Mavic rim). So far the customer service has been
nothing short of superb. No hesitating, "we'll fix it". I'm just so
used to having to put up a fight to get problems resolved these days.

I am also considering taking the opportunity to upgrade the brake set.
Brakes are a crucial safety part on any bike and I want 100%
confidence that pulling the brake lever will bring the bike safely to
a stop with no fuss or oddities. Looking at the SRAM 9.0 brakes. Good
reviews, simple, reliable configuration.

I'll post again after the wheel swap (bike goes in Monday next week).

Tracy