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.

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.

I would go back and politely demand (nice phrase that) a new, /different
brand/ front wheel. They should remedy the problem, whatever it takes (in
this case, installing a tube and tire on a decent front wheel so you can
ride your new bike safely).

Bill "your enthusiasm for riding will work in your favor (for this
relatively small matter and for years to come)" S.

Bassically the forks are not up to snuff. Sorry to tell you.

At that price point it is true.

I have a friend that asked me how fast I went on DH's. I said 35 to 40 mph
and he exclaimed that is crazy my bike shudders at 25 mph. Well my front
wheel cost as much as his whole bike... He really didn't want to believe it
was safe to ride a bike beyond 25 mph. you get what you pay for.

You do have a nce bike just upgrade the forks... or take it back and huy
something int the 800 to 1.1k range.

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.

Thanks, Tracy


along with cleaning the rim you need to clean the brake shoes
themselves. also make sure your headset, brakes, and wheels are
tightened properly


--
Mr_Kingkillaha

"scott" wrote in message link.net...
Bassically the forks are not up to snuff. Sorry to tell you.

At that price point it is true.

I have a friend that asked me how fast I went on DH's. I said 35 to 40 mph
and he exclaimed that is crazy my bike shudders at 25 mph. Well my front
wheel cost as much as his whole bike... He really didn't want to believe it
was safe to ride a bike beyond 25 mph. you get what you pay for.

You do have a nce bike just upgrade the forks... or take it back and huy
something int the 800 to 1.1k range.

I'm trying to nail the problem down a bit before making ultimatums to
the LBS or tossing as much money on a new fork as the bike cost.

If the fork is a problem, then it is secondary. I am rehabing from
some significant medical problems. I am as far from an aggressive
rider as you can get. The craziest I've been so far is a bit of curb
hopping (woo-hoo). I've never even bottomed out these l'il entry level
forks. The original wheel shuddered even at almost walking speed
(while braking). I could feel the brakes grab then release, grab,
release. At moderate speeds the fork really vibrated while braking. No
shuddering problems at all while not braking.

That the problem completely went away for a while after trading the
wheel out would also seem to exclude the forks as the primary culprit.
It would seem to point back to the wheel, the brake
assembly/alignment, or the pads. Or, just some incompatibilty between
one of these parts.

Yesterday I gently scrubbed the brake pads and rims with a 3M abrasive
pad (gray), followed by cleaning with rubbing alcohol. I triple
checked the alignment of the pads and even added a bit more toe-in. I
tweaked the spokes a bit to really get the wheel true. There was some
improvement after all this, but clearly has not cured the problem. I
can still feel a significant change in the amount of grip the brakes
are achieving on the rim as it turn.

I tried my wife's bike as a control and her brakes (same Tekros except
color)are very consistent regarding the grip on the rim. I plan on
swapping front wheel between the bikes and riding both for a while to
see if the problem migrates or stays put.

I am going to check the brake mount as well to be sure they are
properly snugged down. I'll probably toss on a set of Kool-stops as a
data point as well.

I'll post my results.

Thanks for the input, Tracy

Mr_Kingkillaha


along with cleaning the rim you need to clean the brake shoes
themselves. also make sure your headset, brakes, and wheels are
tightened properly


Mr_Kingkillaha,

The rims and pads have been scrubbed with a 3m abrasive pad and
cleaned with rubbing alcohol. Not much help. Still the "grab-no grab"
sensation of the brakes on the rim.

I checked the brake arms and there is a bit of front-back play. The
allen lugs are very snug, but all 4 arms exhibit the same amount of
front-back play. I checked my wife's new Diamondback with Tektro v
brakes. 3 of 4 seem to have about the same amount of play as my
brakes. The 4th has very little play. I have little experience with V
brakes, so I don't know how much play is normal. I consulted my
maintenance manual (by Zinn) and it doesn't discuss the play
tolerances during the brake installation section.

Any thoughts???

Thanks, Tracy

Pizza Man Wrote:
Mr_Kingkillaha


along with cleaning the rim you need to clean the brake shoes
themselves. also make sure your headset, brakes, and wheels are
tightened properly
Mr_Kingkillaha,
The rims and pads have been scrubbed with a 3m abrasive pad and
cleaned with rubbing alcohol. Not much help. Still the "grab-no grab"
sensation of the brakes on the rim.
I checked the brake arms and there is a bit of front-back play. The
allen lugs are very snug, but all 4 arms exhibit the same amount of
front-back play. I checked my wife's new Diamondback with Tektro v
brakes. 3 of 4 seem to have about the same amount of play as my
brakes. The 4th has very little play. I have little experience with V
brakes, so I don't know how much play is normal. I consulted my
maintenance manual (by Zinn) and it doesn't discuss the play
tolerances during the brake installation section.

Any thoughts???
Thanks, Tracy

loose brakes and headset may help amplify the vibration, but i guess
they probably wouldnt be the cause of it.

is the grab-no-grab symptom specific to certain points on the rim? what
i mean is when rolling the bike very very slow, is it just a milder
vibration, or a grab...pause...grab...pause sort of thing?


I tried my wife's bike as a control and her brakes (same Tekros except
color)are very consistent regarding the grip on the rim. I plan on
swapping front wheel between the bikes and riding both for a while to
see if the problem migrates or stays put.


whats the verdict on this? if the vibration sticks with your bike (i
think it will) then switch brake pads only with hers. my guess is she
will now have vibration.

the rubber pads can be ruined if oil has absorbed into them.

please tell me the results of this, i hope i can be more helpful.


--
Mr_Kingkillaha

one more thing.
i cant really tell from the picture of the 4300, but i am assuming all
shoes are the same in that one end is longer than the other.
switching left to right pads so they are backwards may help. tho some
dont reccomend it, mine have always been this way with no problems.
so the way to think of it is the long end of the shoe is pointing
forward, then pointing slightly in toward the rim.

if you think it sounds dumb, look at your non-squealing rear brake, i
bet it is pointing forward too.

hope for the best.


--
Mr_Kingkillaha

I consulted my
maintenance manual (by Zinn) and it doesn't discuss the play
tolerances during the brake installation section.

Any thoughts???

Thanks, Tracy

Basically with faultfinding a problem like this you have to work
through the problem one component at a time. It's a pain, but you have
to pop in a front wheel you know is sound and working from another
bike.Try this first as it's the easiest. If the problem persists then
try a different front brake that is sound and working.This could mean
bad arms or bad pads, but you've isolated it to one part.
If you still have no luck work through fork(flexy fork or slack
bushings) and finally headset.
If it's none of these then either theres something very strange going
on with the headtube, you have a nervous twitch in your brake hand or
someones paying some kind of elaborate practical joke on you.
My guess would be something to do with the fork.

good luck

Cheers

gaz

Basically with faultfinding a problem like this you have to work
through the problem one component at a time. It's a pain, but you have
to pop in a front wheel you know is sound and working from another
bike.Try this first as it's the easiest. If the problem persists then
try a different front brake that is sound and working.This could mean
bad arms or bad pads, but you've isolated it to one part.
If you still have no luck work through fork(flexy fork or slack
bushings) and finally headset.
If it's none of these then either theres something very strange going
on with the headtube, you have a nervous twitch in your brake hand or
someones paying some kind of elaborate practical joke on you.
My guess would be something to do with the fork.
good luck Cheers gaz

Gaz, you are right on. Thanks for the assistance.

In a former life I was a computer network engineer. The problems that
can come up can be really bizarre and difficult. The fix was always
found isolating one component at a time, making no assumptions as to
the functionality of other components. Most of the guys that struggled
always came in assuming it was a single component failure and made
improper assumptions about other components. By component isolation
sometimes I found 2-3 separate failures had occurred. Lumped together,
they look like single horrid mess. Taken individually they were
logical problems with simple solutions.

Below is my ongoing attempt at problem isolation. My weakness is still
product knowledge. These new fangled mountain bikes with all the high
tech gizmos are new to me. I've done a lot of reading in the
newsgroups as well as referring to Zinn's MTB maintenance manual.

Special thanks also to Mr_Kingkillaha for sticking this out with me.

Tracy (update follows).
*****************************

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