Front fork shudder / brake grab

[Anthony DeLorenzo]

Hi All,

I took my road bike out for its maiden voyage last night. The front
brakes were grabbing and causing the front fork to shudder terribly.
Basically unusable. The set-up is a Surly crosscheck frame and fork,
Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon
pads (used), Velocity Dyad rim.

I did a newsgroup search and came up with some things to check out:

- ensure rim is true, especially the vertical trueness
- clean rim
- check pad angle
- check for play in calipers
- check headset (already ruled out)
- new pads
- different wheel


I'll try these things when I go home tonight, but from what I've read
these problems can be hard to fix. Any other advice or suggestions
would be appreciated.

Regards,
Anthony

 

[_]

On Wed, 9 Apr 2008 16:30:28 -0700 (PDT), Anthony DeLorenzo wrote:

> Hi All,
>
> I took my road bike out for its maiden voyage last night. The front
> brakes were grabbing and causing the front fork to shudder terribly.
> Basically unusable. The set-up is a Surly crosscheck frame and fork,
> Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon
> pads (used), Velocity Dyad rim.
>
> I did a newsgroup search and came up with some things to check out:
>
> - ensure rim is true, especially the vertical trueness
> - clean rim
> - check pad angle
> - check for play in calipers
> - check headset (already ruled out)
> - new pads
> - different wheel
>
>
> I'll try these things when I go home tonight, but from what I've read
> these problems can be hard to fix. Any other advice or suggestions
> would be appreciated.
>

Also check that the brake mounting bolt is tight - it's a beginner thing,
but some people (like jim beam) do miss it.

 

[landotter]

On Apr 9, 6:30 pm, Anthony DeLorenzo <[email protected]>
wrote:
> Hi All,
>
> I took my road bike out for its maiden voyage last night. The front
> brakes were grabbing and causing the front fork to shudder terribly.
> Basically unusable. The set-up is a Surly crosscheck frame and fork,
> Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon
> pads (used), Velocity Dyad rim.
>
> I did a newsgroup search and came up with some things to check out:
>
> - ensure rim is true, especially the vertical trueness
> - clean rim

rim AND pad. I like to sand or even use a wee box plane on used pads
to refresh them.

> - check pad angle

Crucial to have proper toe in, especially with Kool stops! Proper toe
in makes LP brakes much less grabby. Again, Kool Stops are really
fussy about this.

> - check for play in calipers

Grease posts, install brake, torque down mounting bolts, and start
with return spring screws turned all the way in, balance arms by
loosening one or the other--this will give you better feel at the
lever.

 

[[email protected]]

On Apr 9, 7:34 pm, landotter <[email protected]> wrote:
> On Apr 9, 6:30 pm, Anthony DeLorenzo <[email protected]>
> wrote:
>
> > Hi All,
>
> > I took my road bike out for its maiden voyage last night. The front
> > brakes were grabbing and causing the front fork to shudder terribly.
> > Basically unusable. The set-up is a Surly crosscheck frame and fork,
> > Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon
> > pads (used), Velocity Dyad rim.
>
> > I did a newsgroup search and came up with some things to check out:
>
> > - ensure rim is true, especially the vertical trueness
> > - clean rim
>
> rim AND pad. I like to sand or even use a wee box plane on used pads
> to refresh them.
>
> > - check pad angle
>
> Crucial to have proper toe in, especially with Kool stops! Proper toe
> in makes LP brakes much less grabby. Again, Kool Stops are really
> fussy about this.
>
> > - check for play in calipers
>
> Grease posts, install brake, torque down mounting bolts, and start
> with return spring screws turned all the way in, balance arms by
> loosening one or the other--this will give you better feel at the
> lever.

you say you ruled out the headset, how did you check to rule it out ?
(or you are saying you are knowledgeable enough to be certain it is
fine )

 

[[email protected]]

On Apr 9, 6:30 pm, Anthony DeLorenzo <[email protected]>
wrote:
> Hi All,
>
> I took my road bike out for its maiden voyage last night. The front
> brakes were grabbing and causing the front fork to shudder terribly.
> Basically unusable. The set-up is a Surly crosscheck frame and fork,
> Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon
> pads (used), Velocity Dyad rim.
>
> I did a newsgroup search and came up with some things to check out:
>
> - ensure rim is true, especially the vertical trueness
> - clean rim
> - check pad angle
> - check for play in calipers
> - check headset (already ruled out)
> - new pads
> - different wheel
>
> I'll try these things when I go home tonight, but from what I've read
> these problems can be hard to fix. Any other advice or suggestions
> would be appreciated.
>
> Regards,
> Anthony

Sure fix: stop the front brake housing at the bottom of the steerer
tube (on the fork crown), not the top (in the headset). Redline bikes
come with an aluminum bolt-on housing stop for this.

This mod removes most of the steerer tube's contribution to the flex
in the system in response to braking.

After stuff has worn in (brake pads, rim, etc.) you might not need the
lower housing stop position any more, but when stuff's new and picky
it makes a big difference.

 

[Leo Lichtman]

"Anthony DeLorenzo" wrote:
(Item 3) check pad angle (clip)
^^^^^^^^^^^^^^^^^^^
Not hard to check. Not hard to fix. Very likely to help.

 

[Anthony DeLorenzo]

Thanks to all for the responses so far. I double-checked everything to
do with the calipers, pads, and wheel trueness. I was able to reduce
the problem but not eliminate it.

I did notice that the brakes are consistently grabbing at one specific
section of the rim. I can't see any difference in the rim itself that
would cause this. I didn't have this problem when the wheel was
mounted on my mountain bike, but the stiffer fork may have just
absorbed it better.

I'm going to try a wheel swap tonight and see if it eliminates the
problem.

 

[[email protected]]

On Apr 9, 9:05 pm, "[email protected]" <[email protected]>
wrote:
> Sure fix: stop the front brake housing at the bottom of the steerer
> tube (on the fork crown), not the top (in the headset). Redline bikes
> come with an aluminum bolt-on housing stop for this.
>
> This mod removes most of the steerer tube's contribution to the flex
> in the system in response to braking.

I second this approach, assuming the simpler changes don't fix the
problem. I'm a big fat guy with a 60cm Surly Long Haul Trucker and a
58cm Bianchi San Jose. The LHT has always been solid as a rock, but
the SJ had terrifying fork shudder until I moved the stop down to the
fork crown; now it's cured completely.

I guess I am a bit surprised to hear that your CC fork suffers from
this. I was actually considering replacing the SJ fork with an LHT
fork at some point precisely because my LHT seems so sturdy. The CC
and LHT fork specs don't look that much different.

 

[Anthony DeLorenzo]

On Apr 10, 9:19 pm, [email protected] wrote:

> I guess I am a bit surprised to hear that your CC fork suffers from
> this. I was actually considering replacing the SJ fork with an LHT
> fork at some point precisely because my LHT seems so sturdy. The CC
> and LHT fork specs don't look that much different.

A few factors probably contribute. I am 6'6" 250 lb., riding a 62 cm
frame with a long head tube and steerer, and the linear-pull (V-brake)
is a lot of brake power for a road fork.

I'm more convinced that the problem is the rim. Even when I just
lightly apply the brakes and turn the wheel on the bike stand, it
noticeably grabs in the same spot every time. LBS has one of those
Mavic rim erasers, I'm going to borrow it and see if it helps.

It could just be some initial wear-in issues as well. With tinkering
and riding the problem has improved, at least to the point where the
front brake is now quite usable, although still annoying.

 

[Anthony DeLorenzo]

On Apr 10, 9:19 pm, [email protected] wrote:

> I second this approach, assuming the simpler changes don't fix the
> problem.

Re: stopping the cable in a different spot, as suggested by a couple
of people (much appreciated!): It's a linear-pull brake, so the
housing runs straight from the handlebar to the brake noodle. No stops
involved. Unless I'm not understanding what you propose.

 

[landotter]

On Apr 11, 1:46 pm, Anthony DeLorenzo <[email protected]>
wrote:
> On Apr 10, 9:19 pm, [email protected] wrote:
>
> > I guess I am a bit surprised to hear that your CC fork suffers from
> > this.  I was actually considering replacing the SJ fork with an LHT
> > fork at some point precisely because my LHT seems so sturdy.  The CC
> > and LHT fork specs don't look that much different.
>
> A few factors probably contribute. I am 6'6" 250 lb., riding a 62 cm
> frame with a long head tube and steerer, and the linear-pull (V-brake)
> is a lot of brake power for a road fork.
>
> I'm more convinced that the problem is the rim. Even when I just
> lightly apply the brakes and turn the wheel on the bike stand, it
> noticeably grabs in the same spot every time. LBS has one of those
> Mavic rim erasers, I'm going to borrow it and see if it helps.
>

http://ashwinearl.blogspot.com/2005/03/garage-mechanic-tip-how-to-rejuvinate..html

Steel wool soap pads also work great. Got 99c?

 

[[email protected]]

On Apr 11, 12:56 pm, Anthony DeLorenzo <[email protected]>
wrote:
> Re: stopping the cable in a different spot, as suggested by a couple
> of people (much appreciated!): It's a linear-pull brake, so the
> housing runs straight from the handlebar to the brake noodle. No stops
> involved. Unless I'm not understanding what you propose.

Sorry, comprehension error on my part (at least); I read right past
the words "linear-pull" and "287V". As far as I know, V-brakes are
immune to the bending head tube issue, because they always have a full
run of housing from the lever to the brake.

 

[Anthony DeLorenzo]

On Apr 11, 11:57 am, landotter <[email protected]> wrote:
> http://ashwinearl.blogspot.com/2005/03/garage-mechanic-tip-how-to-rej...
>
> Steel wool soap pads also work great. Got 99c?

Great link. I'm going to see if the local Canadian Tire carries a
product like that.

Thanks,
Anthony

 

[Paul M. Hobson]

Anthony DeLorenzo wrote:
> Thanks to all for the responses so far. I double-checked everything to
> do with the calipers, pads, and wheel trueness. I was able to reduce
> the problem but not eliminate it.
>
> I did notice that the brakes are consistently grabbing at one specific
> section of the rim. I can't see any difference in the rim itself that
> would cause this. I didn't have this problem when the wheel was
> mounted on my mountain bike, but the stiffer fork may have just
> absorbed it better.
>
> I'm going to try a wheel swap tonight and see if it eliminates the
> problem.

Please do keep the thread updated. This has been a chronic problem on
my Raleigh One-Way despite the best efforts of shops, some friends, and
myself. I think they that my bike just came with a crappy fork that
flexes too much. I'll try new front wheels tomorrow too.

\\paul
--
Paul M. Hobson
..:change the f to ph to reply:.

 

[landotter]

On Apr 11, 7:04 pm, "Paul M. Hobson" <[email protected]> wrote:
> Anthony DeLorenzo wrote:
> > Thanks to all for the responses so far. I double-checked everything to
> > do with the calipers, pads, and wheel trueness. I was able to reduce
> > the problem but not eliminate it.
>
> > I did notice that the brakes are consistently grabbing at one specific
> > section of the rim. I can't see any difference in the rim itself that
> > would cause this. I didn't have this problem when the wheel was
> > mounted on my mountain bike, but the stiffer fork may have just
> > absorbed it better.
>
> > I'm going to try a wheel swap tonight and see if it eliminates the
> > problem.
>
> Please do keep the thread updated.  This has been a chronic problem on
> my Raleigh One-Way despite the best efforts of shops, some friends, and
> myself.  I think they that my bike just came with a crappy fork that
> flexes too much. I'll try new front wheels tomorrow too.

http://www.bikemannetwork.com/biking/p/COMPBRKLEVRD/BR7212
+
Cheap Tektro LP arms and you get kick butt and easy to set up braking.
Not as classic looking as cantis--but sooo not fussy. $55 or so and
you're stopping like a champ.

I'd try a new wheel first. ;-)

 

[Peter Cole]

Anthony DeLorenzo wrote:
> On Apr 10, 9:19 pm, [email protected] wrote:
>
>> I guess I am a bit surprised to hear that your CC fork suffers from
>> this. I was actually considering replacing the SJ fork with an LHT
>> fork at some point precisely because my LHT seems so sturdy. The CC
>> and LHT fork specs don't look that much different.
>
> A few factors probably contribute. I am 6'6" 250 lb., riding a 62 cm
> frame with a long head tube and steerer, and the linear-pull (V-brake)
> is a lot of brake power for a road fork.
>
> I'm more convinced that the problem is the rim. Even when I just
> lightly apply the brakes and turn the wheel on the bike stand, it
> noticeably grabs in the same spot every time. LBS has one of those
> Mavic rim erasers, I'm going to borrow it and see if it helps.
>
> It could just be some initial wear-in issues as well. With tinkering
> and riding the problem has improved, at least to the point where the
> front brake is now quite usable, although still annoying.
>

I'd guess it's the wheel also. I'm 6'10"/230. I have several bikes with
several types of brake setup. The only time I had a problem with shudder
was with a Mavic front rim that came without the anodizing removed on
the brake track. It took a long time (months) to wear through, and until
it did, it was scary grabby.

 

[daveornee]

Hi All,

I took my road bike out for its maiden voyage last night. The front
brakes were grabbing and causing the front fork to shudder terribly.
Basically unusable. The set-up is a Surly crosscheck frame and fork,
Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon
pads (used), Velocity Dyad rim.

I did a newsgroup search and came up with some things to check out:

- ensure rim is true, especially the vertical trueness
- clean rim
- check pad angle
- check for play in calipers
- check headset (already ruled out)
- new pads
- different wheel


I'll try these things when I go home tonight, but from what I've read
these problems can be hard to fix. Any other advice or suggestions
would be appreciated.

Regards,
Anthony

I wonder if the rim has good lateral runout.
If you remove the tire and run a set a calipers around on the braking surface to see if the outside rim width is consistent, you will know.
You would also know by watching the action of the brake arms as they hold down on the rim.

 

[landotter]

On Apr 12, 7:53 am, daveornee <daveornee.37r...@no-
mx.forums.cyclingforums.com> wrote:
> Anthony DeLorenzo Wrote:
>
> > Hi All,
>
> > I took my road bike out for its maiden voyage last night. The front
> > brakes were grabbing and causing the front fork to shudder terribly.
> > Basically unusable. The set-up is a Surly crosscheck frame and fork,
> > Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon
> > pads (used), Velocity Dyad rim.
>
> > I did a newsgroup search and came up with some things to check out:
>
> > - ensure rim is true, especially the vertical trueness
> > - clean rim
> > - check pad angle
> > - check for play in calipers
> > - check headset (already ruled out)
> > - new pads
> > - different wheel
>
> > I'll try these things when I go home tonight, but from what I've read
> > these problems can be hard to fix. Any other advice or suggestions
> > would be appreciated.
>
> > Regards,
> > Anthony
>
> I wonder if the rim has good lateral runout.
> If you remove the tire and run a set a calipers around on the braking
> surface to see if the outside rim width is consistent, you will know.
> You would also know by watching the action of the brake arms as they
> hold down on the rim.

Very true! I just build two wheels to replace a couple of rims with
short flat spots from an impact with a concrete lip. You could
visually inspect the rims by casually spinning them--and they seemed
quite reasonable--I felt a little silly replacing them--but the
braking was atrociously grabby at that flat spot. Nothing short of re-
rimming resolved the problem.

 

[Anthony DeLorenzo]

Well, the problem has been solved.

I took off the Kool Stop pads and went with a cheap set of Avid pads
that aren't as grabby, set up with a generous toe-in. I also swapped
out the wheel (Velocity Dyad rim) for another rim that is a Sun CR18.

At some point I will try the old wheel with the new pads, just to see
if it helps, but for now the bike is happy and I am happy.

Thanks to everyone for all the advice on this thread, especially re
toe-in. I have never had to toe-in a V-brake before, they normally
perform just fine without it, IME.

Regards,
Anthony

 

[Anthony DeLorenzo]

On Apr 12, 5:53 am, daveornee <daveornee.37r...@no-
mx.forums.cyclingforums.com> wrote:

> I wonder if the rim has good lateral runout.
> If you remove the tire and run a set a calipers around on the braking
> surface to see if the outside rim width is consistent, you will know.
> You would also know by watching the action of the brake arms as they
> hold down on the rim.

Now that I have that wheel off the bike I am going to examine it more
closely. I did a basic check with calipers on the rim width in a
couple of spots, but spinning the wheel should give a better
indication. I wouldn't be surprised if the rim is off.