Front brake shuddering! Bad wheels???

Pizza Man said:

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 said:

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

you can see this result here
http://www.cyclingforums.com/t163848.html

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

Quoted message said:

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

Quoted message said:

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 said:

Mr_Kingkillaha

Quoted message said:

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.

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.

I consulted my

Quoted message said:

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

Quoted message said:

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

Pizza Man said:

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

I've never seen wheel shudder from bad rim machining. At least we all learned something new, and your LBS seems to be taking good care of you.

Mr_Kingkillaha <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Pizza Man said:

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

I've never seen wheel shudder from bad rim machining. At least we all
learned something new, and your LBS seems to be taking good care of
you.

King,

Over the weekend I scrubbed the [censored] out of the rims (simple green/
bonami/ gray 3m abrasive pad, rubbing alcohol/paper towels) to be
absolutely sure the rims had no contamination. No help.

I picked up a set of Kool Stop MTB pads (dual compound). Mother of
screaming banshees!!! The squealing is unreal. I tried toe in with a
small paper clip setting, then using a jumbo paper clip as a shim to
set toe in. No improvement at all. The overall gross braking with the
KS MTB pads was better, but the shuddering at anything short of lock
up was maybe a bit worse than the original shoes. Add the squealing,
and fagettaboutit.

I did check the headset carefully and it has a small amount of wiggle
to it. I don't think that can cause the very slow speed grab/no grab,
but probably exacerbates the fork shudder. The LBS had the same
opinion. They will pull off the WTB Dual Duty wheel set and replace it
with a Mavic X139 set. I'm guessing the rim is similar quality and the
Deore hub is a small upgrade over my stock hubs. Hopefully have the
bike back on Wednesday.

It seems kind of odd that the rim machining could be the problem, but
on one side of the rim when I rubbed with crocus cloth I could feel
the rim grab and slip over multiple sections. On the opposite side of
the rim there was some of this, but it was fairly limited. I am
concluding the machining differences are the reason for the varying
friction (sliption?).

I'll post again after the new wheels have properly seated to the pads.

Tracy

Update-

My Trek 4300 went into the shop Monday for the brake shuddering
problems. The rims seemed to be the primary culprit. The headset had a
touch of wiggle in it that may have exacerbated the fork shudder at
higher speeds.

I dropped by the LBS on Thursday morning to test and pick up the bike.
They originally said they would replace the WTB Dual Duty wheel set
with Mavic X138 wheel set. They actually used a Mavic X221 wheel set
(with Deore hubs). These are XC wheels and are narrower (and
presumably lighter) than the original wheels. They are probably a bit
too narrow for my existing tires (factory recommends up to 1.95"
tires, the stock tire is 2.1"😉. I'm not an aggressive off-road rider
(mostly street for me) so the trade to lighter weight is fine. I'll
probably get narrower tires anyway.

I tested the bike. The shuddering was eliminated with the new wheel
set. The headset had not been tightened at this point, so this rules
it out as the primary problem. I will monitor the wheels for a few
days as the original rims worked fine for a few days, then started to
have problems with the shuddering. The brake squealing however was
still horrid. The mechanic swapped out the wheels, but never did a
test drive with the bike to see if the shuddering was fixed. So, he
didn't know the brakes would squeal so badly (sounded like the
beginning of a car accident before the invention of anti lock brakes).
He tried a bit of toe in to no success.

The next tactic was to swap out the brake arms with Shimano Deore V
brakes. After installing the new brakes the squeal was gone and the
brakes were smooth, consistent, and powerful. Unfortunately he changed
2 variables simultaneously (brakes and pads), so I don't know which
was the cause of the squealing. When I get the time I will put the
Kool Stop pads back on to see if the squealing comes back.

I still have two minor concerns. First is the new Shimano brake pads.
I have read many posts discussing how Shimano pads tear up rims. When
I brake the pads sound a bit like mild sandpaper (no point in tearing
up a new set of rims). As a comparison, the Kool Stop MTB pads on the
rear are practically silent when they are applied.

Second, when I ride, the spokes on the new wheels occasionally make a
pinging noise. I don't know if this is a real problem or just the
wheels and spokes settling in. I'll keep a close watch on the spoke
tension and trueness of the rims for a while to be sure nothing bad
happens.

Hopefully this lays this problem to rest. Thanks to all for your
input.

Tracy

Pizza Man said:

I still have two minor concerns. First is the new Shimano brake pads.
I have read many posts discussing how Shimano pads tear up rims. When
I brake the pads sound a bit like mild sandpaper (no point in tearing
up a new set of rims). As a comparison, the Kool Stop MTB pads on the
rear are practically silent when they are applied.

I would change the Shimano pads for Kool Stops. if this is a new set of
Kool Stops you might want to rub them lightly against a mildly abrasive
surface to quickly break them in a little bit, then install (otherwise
I could see a slight squeal happening). after installation, try 2-3
quick firm stops to make sure everything's seated OK and to help break
them in further. then ride.

the shuddering was probably a combination of the wheels and the bad
brakes. I figure with a good set of brakes, you may have noticed some
unevenness with the sidewall but it would not have been so great for you
to completely question the braking ability. a small adjustment should
have been fine. with the new brakes, there will be no noise and the new
wheels should guarantee a solid stopping surface. but all in all, the
play in the headset couldn't help.

Quoted message said:

Second, when I ride, the spokes on the new wheels occasionally make a
pinging noise. I don't know if this is a real problem or just the
wheels and spokes settling in. I'll keep a close watch on the spoke
tension and trueness of the rims for a while to be sure nothing bad
happens.

quite normal with a newly built wheel, this will go away. it also
happens when an old wheel is put in a truing stand and tuned.

it's actually recommended by a lot of people you grab the new spokes and
push them together to "ping" them manually before riding on them. but
if you didn't do that it's no big deal. if you weren't riding on them
that hard when you heard the ping I doubt it would ever create any problems.

have fun,
bri

--

* enjoying the karma *
remove LKJSDFJSD from address to email

bri719 <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Pizza Man said:

I still have two minor concerns. First is the new Shimano brake pads.
I have read many posts discussing how Shimano pads tear up rims. When
I brake the pads sound a bit like mild sandpaper (no point in tearing
up a new set of rims). As a comparison, the Kool Stop MTB pads on the
rear are practically silent when they are applied.

I would change the Shimano pads for Kool Stops. if this is a new set of
Kool Stops you might want to rub them lightly against a mildly abrasive
surface to quickly break them in a little bit, then install (otherwise
I could see a slight squeal happening). after installation, try 2-3
quick firm stops to make sure everything's seated OK and to help break
them in further. then ride.

the shuddering was probably a combination of the wheels and the bad
brakes. I figure with a good set of brakes, you may have noticed some
unevenness with the sidewall but it would not have been so great for you
to completely question the braking ability. a small adjustment should
have been fine. with the new brakes, there will be no noise and the new
wheels should guarantee a solid stopping surface. but all in all, the
play in the headset couldn't help.

Quoted message said:

Second, when I ride, the spokes on the new wheels occasionally make a
pinging noise. I don't know if this is a real problem or just the
wheels and spokes settling in. I'll keep a close watch on the spoke
tension and trueness of the rims for a while to be sure nothing bad
happens.

quite normal with a newly built wheel, this will go away. it also
happens when an old wheel is put in a truing stand and tuned.

it's actually recommended by a lot of people you grab the new spokes and
push them together to "ping" them manually before riding on them. but
if you didn't do that it's no big deal. if you weren't riding on them
that hard when you heard the ping I doubt it would ever create any problems.

have fun,
bri

Bri,

I agree with your clear and concise analysis. I will try roughing up
the KS MTB pads and reinstall them. I just don't like that abrasive
sound of the shimano pads.

Thanks, Tracy

Pizza Man said:

I agree with your clear and concise analysis. I will try roughing up
the KS MTB pads and reinstall them. I just don't like that abrasive
sound of the shimano pads.

sounds cool ... glad the LBS was able to hook you up with the service +
parts necessary to fix the problem! well, post an update in a week or
two if anything seems to change for the worse or anything, I'd be
interested to hear about it in case I ever run into the same thing.
plus I'm probably going to be changing out a lot of the same stuff in
the next few months (brakes most likely, but also wheels and pads).

bri