# Let's talk about fork "shudder".



## Mike T. (Feb 3, 2004)

I'm in the process of ordering a custom CX frame (not for racing; for dirt roads, trails & paved) and have been informed by the builder that the carbon, curved rake fork that they use on their medium priced builds has the possibility of shuddering with a cantilever brake (I'll be using Paul's Neo Retro on the front). He claims that the possibility of shudder will be eliminated if I use a "mini V" brake.

I've asked the question but have not yet received the reply that the fork he will use will be a generic Taiwan CF fork.

What's your experiences with CF fork shudder on a CX, canti-equipped bike?

I don't want a straight fork or a V brake.

I see some of you use the word "shutter". Aren't those for windows? Shudder -

http://en.wiktionary.org/wiki/shudder


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## bopApocalypse (Aug 30, 2006)

My set up - Paul's Neo Retro on a Reynolds Ouzo Pro Cross. (note that my application is completely opposite - mainly racing)

During cross season, I occasionally had a little bit of shudder, but only 3 or 4 times, and only for a fraction of a second.

Sunday, I took the bike out for a trail ride. Realizing that my rear brake is essentially worthless right now (look for a thread on this soon!), I was very heavy on the front brake. The result - lots of shudder.

Not sure what, if anything, the solution is - I've heard talk about the issue with just about every cf fork.


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## Mike T. (Feb 3, 2004)

bopApocalypse said:


> My set up - Paul's Neo Retro on a Reynolds Ouzo Pro Cross. (note that my application is completely opposite - mainly racing)


That's the brake I'll get and the fork I'd like to get but this will be a mid-price CX bike. I have an Ouzo Pro on my road bike.



> Sunday, I took the bike out for a trail ride. Realizing that my rear brake is essentially worthless right now (look for a thread on this soon!), I was very heavy on the front brake. The result - lots of shudder.


Gulp.



> Not sure what, if anything, the solution is - I've heard talk about the issue with just about every cf fork.


My frame's builder is looking into this as we speak and when I get some info from him I'll post it.


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## kreger (Mar 10, 2004)

i mitigated my stutter (pauls neo retro, alpha Q and winwood) with toeing in the brake pads, generously.

hope that helps


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## dannybob (Mar 21, 2006)

there is a theory floated that using a fork-mounted cable stop will minimize shudder. the idea being that most of the shudder is caused by the brake cable being pulled when the fork flexes backward, causing the brake to grab harder. i haven't tried it myself but other folks (somewhere on here, i think) have reported success. mind you, fork mounted cable stops are somewhat difficult to find.


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## dyg2001 (Sep 23, 2004)

It is not as simple as X brand fork + Y brand brake = shudder.
There are other variables:
Brake set-up, especially toe-in
Cable hanger type and height
Headset adjustment
Brake pad
Rim
Conditions--wet, muddy, maybe even humidity & temp, etc.
Housing stop--some people have reported that switching from a conventional housing stop (the kind that slides on the fork steerer above the headset upper bearing cap) to one that mounts to a hole in the fork crown cured their shuddering woes

That said, I think the conventional wisdom is that more flex is associated with a greater risk of shuddering. I've heard more anecdotal accounts of shuddering with light forks like the Ritchey than relatively stout forks like Wound Up.

If I was ordering a custom frameset, I'd get a good steel fork or a good carbon fiber fork from a reputable manufacturer. The fork is not the place to settle for mediocre or unknown quality to save a few bucks.


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## PeanutButterBreath (Dec 4, 2005)

As was mentioned, generous toe-in is a common remedy. I have had shudder with Neo Retros combined with CF, steel and Al forks, and have successfully tuned the shudder out with toe-in.

I'm wondering why you would select a generic Taiwan CF fork for the kind of riding you are doing -- or any kind of riding. YMMV depending on the specific fork, but make sure you are not getting something with all the vulnerabilities of CF and none of the weight or ride quality advantages.


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## jerry_in_VT (Oct 13, 2006)

i dont believe the fork mounted cable hanger thing. assuming a theoretically straight cable pull from brake arm to cable stop, then the movement of the brake arm, and thus the cable, due to fork movement would be almost entirely "translational". The cable/arm would be moving at the bottom of its arc, where a few degrees in either direction are going to result almost entirely in the "x" direction, and hardly at all in the "y" direction.

Do the math. Assume a 6" length of cable from stop to brake arm. Assume the vertical cable run to the brake arm moves a MASSIVE 3 degrees one one direction due to fork flex. No way in hell its three degrees, btw. That would be 6 degrees of forward/backward flex, all occuring between the brake arm and the fork crown...

The new "stretched"length would be 6/cos3 = 6.008234076 inches. A net cable pull of 0.008234076. 8 thou. In comparison, the top of the brake arm would have had to have moved 0.31445 inches. Thats a third of an inch, back into the downtube, over maybe 4 inches of fork length. The front hub would have had to move about an inch or more.

So, I guess my point is that I dont think that 8 thou of cable pull is going to cause a great enough change in brake force to cause brake shudder.

My 2 cents.

Jerry

(I have to add - "checkout www.gewilli.com" and "snicker")


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## jerry_in_VT (Oct 13, 2006)

Oh, and I posted at length before regarding what I believe causes brake shudder. Think is was in the disc brake thread.

The cause of shudder, in my opion, is that the fork is not stiff enough or damped enough, or both, to resist the forces acting on it from THE GROUND at the tire/ground point of contact.

There is nothing to restrict the movement of the entire wheel except the bottom of the headtube. The ground is pushing on the fork via the friction at the tire contact patch. Your body weight is pushing on the fork at the bottom of the headtube due to the brakes being applied. The fork flexes back as a result. Then it springs back, reflexes, springs back, etc.

It needs more inherent dampening. Much like snow board technology did with layers of rubber or titanal or kevlar fibers or whatever they used to reduce chatter.

Or make it stiffer. I think alpha q and ridley have done with their forks. Ridley's is huge in for/aft profile.

J


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## Mike T. (Feb 3, 2004)

PeanutButterBreath said:


> As was mentioned, generous toe-in is a common remedy. I have had shudder with Neo Retros combined with CF, steel and Al forks, and have successfully tuned the shudder out with toe-in.


What's the generous toe-in doing, dialing out some power so as to lessen the load on the fork? If that's so then saving money on that expensive brake might be a reasonable idea no?



> I'm wondering why you would select a generic Taiwan CF fork for the kind of riding you are doing -- or any kind of riding. YMMV depending on the specific fork, but make sure you are not getting something with all the vulnerabilities of CF and none of the weight or ride quality advantages.


I've just been reading Search material on the shudder subject and even the hi-zoot Reynolds Ouzo Pro CX fork is not without issues. If I have to have shudder I'll take shudder and $300 (or so) in the bank.

I'm only assuming my builder uses generic CF forks (for less than top level builds). I'm awaiting info from him.

Nothing is decided yet.


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## vanjr (Sep 15, 2005)

What about a steel fork??


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## jerry_in_VT (Oct 13, 2006)

i think the toe-in gives you more modulation, ie less grabby brakes. if you apply the brakes smoothly, you should not be getting as much force into the fork, and thus shuddering.

if you jam the brakes on, or brake super hard, then you are loading the fork more (decellerating MORE, thus higher forces). Decelleration is how fast the speed is changing, so higher decell is a higher force applied for a shorter time. Toe-in gives you a means to modulate the brake forces so you are not unintentionally jamming the brakes on.

So yah, dialling down the brake power 

I dont think its a coincedence that alot of fast cross racers have crappy brakes...


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## dannybob (Mar 21, 2006)

jerry_in_VT said:


> Oh, and I posted at length before regarding what I believe causes brake shudder. Think is was in the disc brake thread.
> 
> The cause of shudder, in my opion, is that the fork is not stiff enough or damped enough, or both, to resist the forces acting on it from THE GROUND at the tire/ground point of contact.
> 
> ...


Obviously, if shudder still exists with disc brakes then the hanger theory may be bogus. But your mathematical model is oversimplified. The cable does not follow the same line as the fork. The head tube, fork blades, and cable make a sort of triangle of their own, as the fork flexes at the crown, the cable is pulled, since the angle between the head tube and the fork is so obtuse, even a little variance would result in a fair bit of stress on the cable.

I think more than likely, there are several causes of shudder, not all of them existing in every case.

why doesn't this problem exist on road bikes? the forks are as light if not lighter and though the contact patch is certainly not as big traction in ideal situations is better and still no shudder.

can you shoot me the link to the other thread?

dan


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## Mike T. (Feb 3, 2004)

vanjr said:


> What about a steel fork??


I'd go with anything if it was 'guaranteed' not to shudder. I had a Bontrager mtb back in the early '90s with his switchblade fork. It waved back & forth like a leaf in the wind. Awful!

I've got a CF Pace RC-31 rigid fork on my mtb with a disc brake. I've no idea if (or why) a disc brake makes any difference but there hasn't been a hint of shudder in the 5 or so years that I've had it.


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## jerry_in_VT (Oct 13, 2006)

dannybob said:


> Obviously, if shudder still exists with disc brakes then the hanger theory may be bogus. But your mathematical model is oversimplified. The cable does not follow the same line as the fork. The head tube, fork blades, and cable make a sort of triangle of their own, as the fork flexes at the crown, the cable is pulled, since the angle between the head tube and the fork is so obtuse, even a little variance would result in a fair bit of stress on the cable.
> 
> dan


I believe the cable is quite close to parallel to the headtube (and thus fork steerer, etc) in most cases when using a head tube mounted cable stop. Thus, the model I assumed is pretty close to accurate. 

Agreed, the farther your cable is out of parrallel with the fork, then the greater the angle and thus the greater the change in LENGTH of the cable relative to movement of the brake arm. If you hang the cable off the stem faceplate, for example, you MAY be causing worse shudder.

I still think that the angles involved were padded enough to make the simplification of the cable angle moot. I personnally do not believe it causes any noticable affect on brake shudder. 

I think the second post I made regarding what does cause shudder is a much more likely engineering analyses of the forces and reactions, as they are much much greater magnitude then the cable pull scenario.

Again, just my opinion.

J


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## Mike T. (Feb 3, 2004)

jerry_in_VT said:


> So yah, dialling down the brake power


If that's the reason, then has anyone tried trimming pad size (contact area) down?



> I dont think its a coincedence that alot of fast cross racers have crappy brakes...


Yeah I'm sure sheer stopping power isn't high on their agenda eh? Well modulated slowing control would be much more important I would think. Or maybe they just get on with the job, ride and leave debates like this to us.


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## jerry_in_VT (Oct 13, 2006)

Mike T. said:


> I'd go with anything if it was 'guaranteed' not to shudder. I had a Bontrager mtb back in the early '90s with his switchblade fork. It waved back & forth like a leaf in the wind. Awful!
> 
> I've got a CF Pace RC-31 rigid fork on my mtb with a disc brake. I've no idea if (or why) a disc brake makes any difference but there hasn't been a hint of shudder in the 5 or so years that I've had it.



Disc forks are by design alot stiffer then canti forks because the brake forces are at the drop out, hence a longer lever arm. 

I would surmise that this added stiffness helps reduce shudder. Again, I think its the result of the forces applied at the ground to the tire contact patch, translate back UP to the lower fork race, and applied over the entire fork/wheel assembly in between. If one section of the assembly is really thing/flexy, then you should see more shudder. On a disc fork, that whole fork leg is stiffer, where as on a canti fork, the lower leg can be thinner to tune in some comfort or what not. I think this makes shudder worse in that case. Assuming the same fork material, etc.

I would love to see some damping rate data on CF verses steel. My memory/gut tells me basic carbon fiber layup is going to be less inherently damped then basic steel. Anyone?

J


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## PeanutButterBreath (Dec 4, 2005)

My friend just built up a rigid 29er. Fairly spindly steel fork. 185mm rotor. Brand new pads. Big-time shudder.

I think that shudder is caused by braking forces overpowering the fork legs. They flex as far as the braking forces will force them back, then the pads slip and the cycle repeats. I'm not sure that phenomenon could be dampened out.

I believe that the answer lies in balancing the brakes so that they can not overpower the fork legs. Toeing-in effectively weakens the brakes ability to grab the rim.

Now that the trails are dry I've noticed how much of the braking power I have tuned out of my MTBs. I hate grabby brakes.


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## jerry_in_VT (Oct 13, 2006)

dannybob said:


> why doesn't this problem exist on road bikes? the forks are as light if not lighter and though the contact patch is certainly not as big traction in ideal situations is better and still no shudder.
> 
> 
> dan


I get wicked shudder on my road bike with an Easton E90SLX. Terrible.

J


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## jerry_in_VT (Oct 13, 2006)

PeanutButterBreath said:


> They flex as far as the braking forces will force them back, then the pads slip and the cycle repeats. I'm not sure that phenomenon could be dampened out.


Pad slip...hmmm...that is an interesting idea. I suppose on a canti with a crummy compound it could slip. It would have to be locked up first, ie grabby.

On a disc fork that sounds like something that could happen though, less margin for modulation on a disc cause the forces are so high and the lever so small. Interesting.

Slow - mo fork cam video, anyone?


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## PeanutButterBreath (Dec 4, 2005)

Here is my crackpot theory:

If the brake grabs too hard, it will flex the fork back to a point where the tension in the fork exceeds the pad's grip on the rim causing the pads to slip, which in turn allows the fork to spring back (rebound point). But soon as the system returns to a state where the brake has the upper hand again and the whole cycle repeats. This goes on until enough deceleration has taken place to prevent the brake from forcing the fork to the point where it rebounds.

If the brake and the fork are in balance, the fork is never forced to its rebound point.

I don't think the brake would have to lock the rim for this phenomena to take place. It would only have to grab hard enough to flex the fork back to the point where the forks spring action is stronger than the pad's grip.


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## Mike T. (Feb 3, 2004)

So now I'm wondering if it might be a waste of money getting the highly-regarded Paul brakes. Maybe, to stop the shudder, I'll have to reduce their power to that of a $20 set of Tektros. But then I suppose _they_ would squeal enough to wake the dead.

I feel I'm entering a hornet's nest here.

Does anyone know of a set of el-cheapos that won't overpower the fork, are easy to adjust and don't squeal? Yes I'm aware that MFMV.


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## sidsport (Mar 3, 2007)

Ok, this this is on a road bike with calipers mind you, but I never had brake shudder until I got a new set of wheels (custom build with IRD Cadence rims). It can be reduced with more toe-in. Don't know if the new rims or more grabby, the wheels are stiffer, of if the new wheels disrupted the feng shui of the bike.


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## PeanutButterBreath (Dec 4, 2005)

Re-emphasizing the "crackpot theory" part, if there is anything to it the secret to maximum braking power is a stiff fork and a brake that can be tuned to the maximum amount of strength before shudder sets in. Paul's are easy to tune. They are also light, well constructed in the US and nice looking. They also come with Kool-stop pads, and pad compound plays a part for sure. They are damned expensive though.

Cheap brakes, IME, are not as easy to tune and come with lousy pads. They often have wimpy springs, rust & corrosion prone components, poor bushings, press-fit parts that fall out (Avid) and cheesy little screws that like to seize and strip.

Again, emphasizing the "crackpot theory" part, your best bet is to get a fork worthy of a decent brake.


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## dannybob (Mar 21, 2006)

jerry_in_VT said:


> I get wicked shudder on my road bike with an Easton E90SLX. Terrible.
> 
> J


That sucks.


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## Mike T. (Feb 3, 2004)

PeanutButterBreath said:


> ................your best bet is to get a fork worthy of a decent brake.


I read in "search" of a fella with a vibrating Empella fork (don't they specialize in CX bikes?) and a vibrating Ouzo Pro. There's a Lurker on this thread who is asking our frame builder the same questions as I and he's willing to spend a king's ransom on a fork where I want a lower price fork. The builder isn't sure that there *is* a fork that won't vibrate. He's looking into it for us.

So, PBB, what's a non-vibrating fork worthy of a Paul brake?

The builder is suggesting a Mini-V brake. Can I assume (I haven't asked the builder yet) that this is a low power brake?


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## 1speed_Mike (Feb 16, 2004)

Mike T. said:


> I read in "search" of a fella with a vibrating Empella fork (don't they specialize in CX bikes?) and a vibrating Ouzo Pro. There's a Lurker on this thread who is asking our frame builder the same questions as I and he's willing to spend a king's ransom on a fork where I want a lower price fork. The builder isn't sure that there *is* a fork that won't vibrate. He's looking into it for us.
> 
> So, PBB, what's a non-vibrating fork worthy of a Paul brake?
> 
> The builder is suggesting a Mini-V brake. Can I assume (I haven't asked the builder yet) that this is a low power brake?


Well, I wouldn't say "willing to spend a king's ransom", but I getcha 

I'm not sure what kind of data points this will add, but I'm currently using a set of Pauls Neos on an Empella Bonfire with carbon Empella fork. Previous to the Empella, I had a Ti Seven SS CX with an Alpha Q and the same Pauls. In the years I've been using my Pauls with these 2 forks (which, included some racing and lots of trail riding and winter riding), I've had very, very little shudder. I made sure to properly toe the pads-out at the ends and it's not been a problem for me. FYI, I'm 135lbs.

From my readings on the topic (since I'm looking at the same bike/fork/brakes as Mike T), it appears to be a problem with nearly every fork, be it carbon, aluminum or steel, Reynolds, Alpha Q, Easton, etc. Most recommended solution is toe-in. Seems to work for me, at least enough that it hasn't been a noticeable problem.

So, I guess based on my own experiences, I'm likely going to go with an Alpha Q.


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## PeanutButterBreath (Dec 4, 2005)

Mike T. said:


> So, PBB, what's a non-vibrating fork worthy of a Paul brake?


I'm not sure there is a non-vibrating fork either. There is just so much that you can expect out of a CX bike. Crank up the braking power and you will have to beef up the fork. That will likely have a negative effect on ride quality and weight.

FWIW, I think that shudder can be tuned out of most set-ups and maintain adequate braking power.


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## Dan Cas (Aug 3, 2002)

*Once again*

Please scroll down to post # 9

http://forums.roadbikereview.com/showthread.php?t=67338&highlight=fork


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## Mike T. (Feb 3, 2004)

Dan Cas said:


> Please scroll down to post # 9
> http://forums.roadbikereview.com/showthread.php?t=67338&highlight=fork


That's quite a theory you have there Dan. I would imagine that the engineer types around here might have some comments on that. You're claiming that the forward and backward flexing of the headtube is the source of fork shudder and not the flexing of that 39cm cantilever of a fork?


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## PeanutButterBreath (Dec 4, 2005)

Dan Cas said:


> Although the fork can change the resonant freq, it is a form of chassis shake,more common in steel than aluminum frames.Although it presents at the fork,it is the top/head/down tube triangle flexing. Steel is better at elongating than al.


That is pretty dubious. I would expect a lot of bad things to happen before forces translated from the front wheel, through the fork and into the main triangle caused it to deform. Moreover, I never had worse shudder than on my initial build-up of a Cannondale CX frameset. Nice, stiff Al frame with a flexy CF fork.



Dan Cas said:


> This shuddering is called fork chatter and is common in cyclocross
> single bikes with canti brakes.It is the brake grabbing the rim,the
> fork/top/headtube flexing,then breaking free,then happening again.One
> framemaker I had attacked the problem by using a larger top tube and
> ...


I agree on the initial cause of the problem (grabby pads), but I have not had a problem with pads seating or needing to be moved around at all once they are toed-in and the problem is remedied. I usually don't have to touch them until they need replacement.



Dan Cas said:


> I have confirmed this by using a disc/canti fork on the same frame.I
> never had a problem with the disc brake,and chatter would occur with the
> canti brake.It was worst when is was damp or humid.OK when dry or
> raining,but bad when damp.It is a pain.


This is not a good experiment. You have two completely different braking systems. What does it prove that they yeild different results? And if the problem is the main triangle, why would the brakes make a difference? Your result are more likely a result of the specific installations you were working with.

Disc forks can shudder too, btw.


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## Mike T. (Feb 3, 2004)

1speed_Mike said:


> Well, I wouldn't say "willing to spend a king's ransom", but I getcha


Ok, I'll re-phrase that. *Able* to spend a king's ransom. How's that?  



> From my readings on the topic (since I'm looking at the same bike/fork/brakes as Mike T), it appears to be a problem with nearly every fork, be it carbon, aluminum or steel, Reynolds, Alpha Q, Easton, etc. Most recommended solution is toe-in. Seems to work for me, at least enough that it hasn't been a noticeable problem.


You're an engineer Mike. Ok, maybe not a structural engineer but prolly smart enough to be one. Does this toe-in reduce a harmonic vibration that maybe is causing the fork to flex (due to the grab-release of the vibration) or does the toe-in reduce pad contact and therefore braking power, which lessens the force on the fork?

Do you think that shortening the length of the pads might have the same effect on this as toeing them in? I wish I had a vibrating fork to try this on.


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## winstonc (Nov 18, 2002)

jerry_in_VT said:


> i dont believe the fork mounted cable hanger thing.
> ...


Well, you can criticize the theory all you want, but at the end of the day, a fork-mounted cable stop just works for a lot of people.

I had pretty bad squeal and stuttering on two bikes before the fork-mounted cable stop, and with the cable stop, it went away. The problems occasionally come back when the rim is slightly wet, but even then it's not nearly as bad as it was.


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## bwcross (Sep 30, 2006)

PeanutButterBreath said:


> I'm not sure there is a non-vibrating fork either. .


My IF steel fork doesn't chatter. The Alpha Q I had before it chattered badly out on the road, which is why I went back to steel this time around.


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## Thor (May 25, 2004)

What? Hardly a word on this topic about V brakes supposedly solving everything!

My former Ridley Crosswind/Python full CF fork had horrible chatter (shudder too) using Spooky brakes with Kool Stop black pads. Massive toe-in and a long straddle cable helped until the pads wore a little. The it came back with a vengence.

When the bike did the big 'ol splat on the pavement I had an opportunity to change out some components. After replacing the frame, fork, headset, handlebars, brifters, stem, brakes, cables, pads and wheels, the chatter went away! 

The new build is Redline Team, Ritchey WCS full CF, Paul Neo with Koolstop Salmon and it all works great together. The salmons were a little grabby before they came to know the wheels, but since they have been worn in a little the braking is excellent.Good modulation, good stopping power and no chatter. 

Thor


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## Mike T. (Feb 3, 2004)

Thor said:


> What? Hardly a word on this topic about V brakes supposedly solving everything!


I think I mentioned somewhere above that my potential frame builder suggested Min-v brakes as the cure for fork shudder. I just can't picture a 'real' cross bike without cantis. But then maybe I said that about toe-clips & straps and bar-end shifters too.



> .........Ritchey WCS full CF, Paul Neo .........Good modulation, good stopping power and no chatter.


That's the setup I'd really like but I was hoping to get away with putting less money into a fork than that. That might be unrealistic though.


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## 1speed_Mike (Feb 16, 2004)

Mike T. said:


> Ok, I'll re-phrase that. *Able* to spend a king's ransom. How's that?


LOL! That's even worse! I'm a single Dad of 2. And, let me tell you, hockey equipment ain't cheap! So, I'm keeping this CX'er reasonable.












> You're an engineer Mike. Ok, maybe not a structural engineer but prolly smart enough to be one.


Actually, I did my B.Eng and M.Eng in Civil Engineering ~10-yrs ago, but have been working in the telecom biz since graduating as a Software Engineer. So, I'm very stale when it comes to structures, dynamics, etc.



> Does this toe-in reduce a harmonic vibration that maybe is causing the fork to flex (due to the grab-release of the vibration) or does the toe-in reduce pad contact and therefore braking power, which lessens the force on the fork?


IMO, toe-in will do both. Any system/structure will have a natural frequency. Once that natural frequency is reached, the system can start to vibrate violently. If you had shudder with a stock, non-toed-in brake, then by adding some toe-in, you've changed the natural frequency of the system, which chould reduce the shudder (or, at least move it to a different point in the braking).

When the pads are toe'd and the brakes are applied, only the front tip will engage. The more you pull the lever, the more of the pad that is hitting the rim. You can feather/modulate this much better than a pad that's not toe'd-in. A pad that is sitting flat will have the entire pad engage at the same time, which can be very off/on braking. This can also cause the pad to grab easier, which could lead to shudder.



> Do you think that shortening the length of the pads might have the same effect on this as toeing them in? I wish I had a vibrating fork to try this on.


Yes and no. Again, if you had shudder with your stock set-up, cutting the pads to a shorter length would change the natural frequency. So, yes, I guess that could help. But, I prefer to toe-in since I like the modulating effect it provides.

Ya, I just wish I'd known about this problem when I was doing my M.Eng as I could have used my schools facilities to use FEA to model different forks/brakes and then use the lab to test it in real life. Ah well, than can be for someone else, I guess.


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## PeanutButterBreath (Dec 4, 2005)

bwcross said:


> My IF steel fork doesn't chatter. The Alpha Q I had before it chattered badly out on the road, which is why I went back to steel this time around.


Well, there you go. IF forks are shudder proof.


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## 1speed_Mike (Feb 16, 2004)

PeanutButterBreath said:


> Well, there you go. IF forks are shudder proof.


One problem though....it's straight-bladed. Mike T wants curved.


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## PeanutButterBreath (Dec 4, 2005)

Pretty much any combination can work shudder free. Most just need a little attention to how they are set-up.


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## Mike T. (Feb 3, 2004)

Ok I'm with ya on all that MB - except the part where you're pleading poverty. Pensioners like me (I sound like I'm 87 don't I?) can plead poverty.

Yes my shortened pad idea would just change the resonance point to another speed or load. Better to be able to moderate it oneself with lever pressure eh? Maybe more or less on certain days or (sa - my cat just typed that) other conditions.

Talking about conditions and resonating frequencies. You know I have a long history of mtb disc brakes and their issues (sigh!). Back in '99, on my Seven Sola mtb with Magura Louise disc brakes, I had pefectly quiet, squeal-free braking. I went on a three-day riding trip at Jim Thorpe PA and it was 98 degrees (err that's f) and so humid I've never felt anything like it. Just for those three days and never before or after those three days I had a low moaning vibration from my rear brake. The seat stays were acting like a tuning fork. Someone walking alongside me could feel it. Both Rob V and Thor had no suggestions other than taping thick rubber to the stays as an experiement in damping.

So, I'm sure that vibrations, squeals, shudders or even 'shutters' have many reasons for their existence.


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## Mike T. (Feb 3, 2004)

PeanutButterBreath said:


> Well, there you go. IF forks are shudder proof.


Mike B just suggested this in an e-mail to me (yep we know each other) and I told him -

1. Straight forks over my dead body.
2. I'll take a Goodyear rubber fork first.


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## Mike T. (Feb 3, 2004)

PeanutButterBreath said:


> Pretty much any combination can work shudder free. Most just need a little attention to how they are set-up.


This is the way I'm leaning at the moment. There are too many variables and too many personal findings (in the Search results) to provide one answer to this. But squeal & judder is one of the reasons I quit mtb rim brakes 9 years ago. I've been in braking nirvana ever since.


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## Dan Cas (Aug 3, 2002)

*shorter brakes*

I tried cutting some brakes down- I called them "Hitler" brakes beacause they were as long as his mustache. No luck,maybe even worse.

Back to the naysayers- the disc brakes did not grab,therefore I had no chatter.Yes the fork flexed,a scary amount,but no chatter. The rim brakes grab,and therein lies the problem.

I had a friend whose brand new Cannondale chattered,but it was completely different than my steel frame.His was a high frequency,almost a shriek,and the bike would actually creep sideways. He changed pads,and then brakes,and tuned it out.

Back to my story- My first fork was a 395 A-C,curved,43mm rake, with 1 mm thick steel blades. I was so sure it was the fork that I asked them to make me a 1.2mm bladed fork.The problem changed from 7cps rubber hammer shudder to 15 cps steel hammer shudder and was much worse overall.

They replaced the frame and made the following change: Changed the top tube from 1" diameter to 1 1/8. Fork stayed at 1mm blades,and the problem was much reduced.

The next step they took was to change the head tube diameter from 1 to 1 1/8. Note that the steel steerer at .065 in 1 inch was more than strong enough. They changed to 1 1/8 to get a larger weld area on the front triangle.

Next step was to shorten the fork. This accomplished 2 things- made the legs somewhat stiffer due to the reduced length, but more importantly, they lengthened the headtube the 15 mm to move the fulcrum point down and give the fork less leverage on the front triangle.

I think you have to look at this as a gestalt design issue, not at the tips of the fork blades. Since someone found a chatterless fork, I suggest everyone buy that.


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## Float (May 27, 2005)

*De Tuned Brakes*



jerry_in_VT said:


> i think the toe-in gives you more modulation, ie less grabby brakes.


From my experience (Easton EC90 CX) you hit the nail on the head - I'm using Kool Stops Salmon: for severe weather brake pad with more than recommended toe-in. They allow me to apply the brake with modulation. I get way more power out this brake set up than I need, wet or dry.


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## jerry_in_VT (Oct 13, 2006)

phew - lotta of comments here! Last night, since my driveway finally melted down to dirt yesterday, I took my bikes out on my hill at low speed to try to see what was happening.

Couple observations, but in summary, I think fork flex is a major contributor, but not in the way you might think. I now am feeling the brake grab/release theory as the actual mechanism that causes the shudder. Here is what I observed:

Road bike, stock shitmano ultegra brakes, easton E90SLX road fork. Low speed, 15% grade driveway, from dead stop, all front braking. This is where I get alot of shudder usually, not out on the road. I really think I am seeing the brake grab and release. It seems like the calipers have small pad area, and the caliper also moves alot under heavy braking (or the fork/wheel move relative to the brake pad). Its a very flexy fork. 350 grams...

It seems the movement of all the parts under heavy flex cause the pads to slip for a split second. Could be the arm itself twisting under the forward rotational load of the wheel till the pad twists off the rim a bit, loosing grip and then the wheel slips, reducing brake force, so the arms release and grip again, wash rinse repeat.

My cross bike test seemed to support this mechanism, but of course its a totally different setup. Just easier to see as the parts are bigger and move more. I have the Sachs, with the Sachs fork. This is what I would call a soft/flexy fork, sort of. Its steel, so its not the same huge stiff leg as a carbon. Brakes are XT cantis. Shimano pads. At a stop, I can SEE the brake bosses and fork legs flex OUT under braking. Like we used to buy brake boosters for (remember those?). This was even more noticable on the rear.

Also, the canti arms flex alot. This is something I have seen before with these and other brakes. Its been my experience that a high end brake arm is lighter and flexier, and ALSO has a better "feel". I have these same brakes in black LX trim, and they feel like crap. They also flex LESS. I think its all to do with your ability to modulate the brake power with an inherently flexy set up. I think the fork also adds to this as it feels nice, but you can see it flexing alot.

Now, on the rolling test, again on a STEEP hill at LOW speed, I got it to shudder (I dont get that in races). What I saw was interesting. You can SEE the canti post twisting as the wheel rotates forward, pulling the pad with it. Then the pad gets twisted enough that is looses contact area, and slips, then the whole thing flexes back (TWISTS) and boom, you have grip again.

Let me state that I did not see any influence of the front to back flex of the fork under braking on the shudder. I have alot of movement with both forks, but had to make it shudder by really braking hard.

So again, I think the shuddering is the brakes releasing and grabbing, not the fork flexing and springing back, in the direction of travel. That said, I did also get a version of shudder under less hard braking down the muddy hill where the front tire was breaking free and mini-skidding and then grabbing. I think if i got this kind of shuddering in a race I would be falling down though. Maybe that it what some people are experiencing though.

Last thing I will say is that I am really picky about my brake feel. I like the levers loose, and the whole thing flexy. I hate a tight lever and hard brake. I see alot of people with bikes set up this way, or with cheapie stiffy brakes, and I cant imagine riding that way. And I dont get shudder normally on my flexy front end cross bike.

J


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## fastitus (Sep 15, 2007)

I don't pretend to be a real CX veteran (2 years). My Ritchey WCS fork had horrible amounts of chatter and grabbing at first. When I tried the toe-in fix, it worked real well. You have to put a little more pressure on the brakes, but otherwise seems to work good. Also need to replace the pads before important races, since they wear badly with the toe-in.

Did the CX nationals at KC, and one potential problem under icing conditions with the toe-in method is the ice builds up behind the pads, and the braking power is gone. Or at least that's what happened to me. Not sure if there is really a fix for that.


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## Mike T. (Feb 3, 2004)

jerry_in_VT said:


> I think the shuddering is the brakes releasing and grabbing, not the fork flexing and springing back, in the direction of travel.


Woooo that's an interesting thought Jerry.

Is shudder the backward flexing of the fork due to the brake retarding the wheel and the momentum of the bike pushing the headtube forward? But if this was so, why wouldn't the fork just stay flexed back until the load was removed? Surely, for it to oscillate, the brake itself has to come into play. So do the canti studs rotate around the fork leg axis until the pad loses grip? Maybe the old mtb rim brake 'booster' would help here as you said. In their day they were to stop fork leg splaying due to pad reaction to the rim. I wonder if they would be useful for this secondary roll of preventing canti boss rotation. I now wish I had paid more attention in Physics class.

If I ever get a CX bike with a shuddery fork I'll try my Ti custom ones ~ if they will fit.


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## J-K (Nov 5, 2006)

Interesting thoughts here. This topic could go on until next cross season :cornut:.

The "pad slip because of a flex and spring back movement in the brake and fork parts"-hypothesis sounds reasonable. 

If that is true, what is it in V-brakes or mini-V's that seems to cure or at least minimize shudder? They do cure the problem... I have found that out first hand and read a lot of similar observations. If you would want to use V-brakes for cross is another discussion, but the reason for them to cure shudder could shed light on the causes.


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## jerry_in_VT (Oct 13, 2006)

i dunno about all this talk regarding swapping a part solving the problem. You could switch from one canti to another, and in the process, you are forced to reset up your brakes. Set em up a little looser, and the shudder goes away, for example. Way too many variables. I think its more a function of brake set up so its quite possible that changing to a fork hanger, or changing to v brakes changes the previously poor brake pad setup enough to fix the problem.

If I had to guess on V's, I would say the smaller pad and the more powerful brakes/longer arms gives a more modulating brake, in general. Dunno.

I really think that the shudder is related to brakes grabbing and releasing, now that I spent time observing it. Fork flex/oscillation in and of itself is a fairly "smooth" action. The shuddering is (almost by definition) a harsh, on/off chattering action which a fork flexing and springing back is not. Unless of course its caused in a certain case by the tire "micro skidding" on the ground. I mentioned how I observed that in my previous post. But i think that was an isolated thing that I artificially created. Front tire skids typically end badly, and shuddering can go on for a long time without trips to the ER.


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## jerry_in_VT (Oct 13, 2006)

J-K said:


> Interesting thoughts here. This topic could go on until next cross season :cornut:.
> 
> The "pad slip because of a flex and spring back movement in the brake and fork parts"-hypothesis sounds reasonable.
> 
> If that is true, what is it in V-brakes or mini-V's that seems to cure or at least minimize shudder? They do cure the problem... I have found that out first hand and read a lot of similar observations. If you would want to use V-brakes for cross is another discussion, but the reason for them to cure shudder could shed light on the causes.


I would suggest it is small pads and large leverage with a longer then canti brake arm which results in more arm flex. All of which equals better modulation.


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## Float (May 27, 2005)

Kool Stop Salmon: for severe weather - helps soften the initial spike in the oscilation (with a good amout of toe-in)

Give it a try and you will see the light!


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## Mike T. (Feb 3, 2004)

We've had great debate, talk and info about the juddery fork syndrome over the last few days. It was my hope to find the definitive solution to this issue but of course it's not to be. When my CX frame is made I will be completely new to CX bike riding (I'm not racing) but certainly not new to canti brakes, their issues of old and even flexy forks (my ol' Bonty mtb). Before I make any decision I almost need an iron-clad guarantee (good luck eh?) that I won't be buying new frustrations.

Both Mike B. (1speed-Mike) and I are in this situation and we're considering ordering from the same maker - the prolific Cycles Marinoni in Montreal Quebec. This will be about my 5th Marinoni over the past 30+ years.

Builder Luc is very confident that carbon forks, Tektro Mini-v brake and travel agents will work well together.

Quotes from Luc -
"We notice that a lot of the carbon forks that are light will have shuddering specially with a more power brake. If you use a Mini-V type brake, it will not shudder."

"We have been using Mini-V for more than 5 years and they work good. What we use is a traveller agent to help with the cable pull so you can get rim clearance and enough power."

There have been a couple of interesting threads on the Mini-v - here  and here. 

So, at the present time, with the info I have, this is the way I'm heading. Unless new info surfaces of course!


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## bwcross (Sep 30, 2006)

Just out of curiousity, with all the folks with the Cross Checks on this forum - are you getting brake shutter with your big boat anchor forks?


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## 1speed_Mike (Feb 16, 2004)

> So, at the present time, with the info I have, this is the way I'm heading. Unless new info surfaces of course!


Based on what I've read here, there and everywhere, Luc's comments, etc., I think you are making the best choice! :thumbsup: 

For me, since I've already got Pauls, I'm going to stick with them. Fork will likely be an Alpha Q, since I've used this combo before in the past with no real issues. If, I end-up with shudder, despite proper toe-in, etc., then I'll follow-up with you to see how your Mini Vs/TA are doing. At which point, hopefully, you'll be able to say that you are riding shudder-free!


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## 1speed_Mike (Feb 16, 2004)

bwcross said:


> Just out of curiousity, with all the folks with the Cross Checks on this forum - are you getting brake shutter with your big boat anchor forks?


Ya, good question! :thumbsup:


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## jerry_in_VT (Oct 13, 2006)

Marinoni!! Nice! We used to see lots of those around New England (road frames) back in the 80s. My local shop is the only one around that I have seen that still imports them. He is a single guy, literally crack in the wall/store front as wide as the door kinda shop. Its like harry freakin potter.


Jamie Driscoll works there too. Village Bike in Richmond, VT. Gene is the owner and is a long time marinoni guy. He had a repainted old one there he was restoring, it had the old fishnet paint scheme. He had to have that custom done by Mrs. Marinoni, I guess she was the painter back then. He said they dont do it anymore but busted it out for him.

He always has a couple custom marinonis getting built up. He is also a very old school bike guy, has the parts glacier under the bench to prove it. And he knows cross bikes.

Guys like that are the kind of people to ask if you want second opinions. They will all be lost when the small LBS's finally all get squeezed out.

Off topic, I was in the Marinoni factory back in the late 80s when i was starting college in montreal. I bought a handful of braze-ons and converted my first road racer from high school into my first cross racer...good times...


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## Mike T. (Feb 3, 2004)

1speed_Mike said:


> I'll follow-up with you to see how your Mini Vs/TA are doing. At which point, hopefully, you'll be able to say that you are riding shudder-free!


At my age I prolly can't get up a big enough head of steam, or pull the levers hard enough, to create shudder.


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## winstonc (Nov 18, 2002)

bwcross said:


> Just out of curiousity, with all the folks with the Cross Checks on this forum - are you getting brake shutter with your big boat anchor forks?


I have a Cross Check fork on my bike, and I did get strong brake shudder with my previous brakes (Avid Shorty 4) and my current ones (Tektro Oryx), but it went away when I installed a fork-crown-mounted cable stop.


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## chimivee (Mar 14, 2007)

I have a Conquest Pro w/ [then] stock aluminum fork and Kool Stop Salmon pads. Had a fair amount of brake shudder. Added a fork-mounted cable hanger (originally for the purpose of running my stem lower), and now have minimal shudder. I know nothing about fork dynamics, but this $10 doohickie worked.


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## jerry_in_VT (Oct 13, 2006)

did you guys that had great luck with the fork cable hanger have to change your straddle cable angle in order to make it fit? i barely have any straight cable as it is on my brakes with my short headtube. It would be tough to make this fit without really flattening the straddle cable. Of course e-richie does not drill the fork anyway...


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## chimivee (Mar 14, 2007)

jerry_in_VT said:


> did you guys that had great luck with the fork cable hanger have to change your straddle cable angle in order to make it fit? i barely have any straight cable as it is on my brakes with my short headtube. It would be tough to make this fit without really flattening the straddle cable. Of course e-richie does not drill the fork anyway...


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## Mike T. (Feb 3, 2004)

jerry_in_VT said:


> Marinoni!! Nice! We used to see lots of those around New England (road frames) back in the 80s. My local shop is the only one around that I have seen that still imports them. He is a single guy, literally crack in the wall/store front as wide as the door kinda shop. Its like harry freakin potter.
> Jamie Driscoll works there too. Village Bike in Richmond, VT. Gene is the owner and is a long time marinoni guy. He had a repainted old one there he was restoring, it had the old fishnet paint scheme. He had to have that custom done by Mrs. Marinoni, I guess she was the painter back then. He said they dont do it anymore but busted it out for him.
> He always has a couple custom marinonis getting built up. He is also a very old school bike guy, has the parts glacier under the bench to prove it. And he knows cross bikes.
> Guys like that are the kind of people to ask if you want second opinions. They will all be lost when the small LBS's finally all get squeezed out.
> Off topic, I was in the Marinoni factory back in the late 80s when i was starting college in montreal. I bought a handful of braze-ons and converted my first road racer from high school into my first cross racer...good times...


Thanks for sharing all that Jerry. I was at Marinoni's shop in the fall a year ago and I got the honor of Giuseppe coming out of the back room to visit. I recently heard that he wins his age group (by about 12 minutes) at the Mt Washington hillclimb. He's now 68. Here's builder Luc, myself and Mr. Marinoni himself. He was lookin' kinda fit that day -


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## towerscum (Mar 3, 2006)

*no shudder here*

This is what I have going. No shudder here...not sure why.
Waterford bent blades custom fork to match custom Waterford frame
Pauls Neos
Ceramic Mavic OP rims,road Koolstop ceramic pads w/ about two creditcard thickness toe in
Hanger 3" up above tire 
Weird looking Belgum made bent plate cable hanger
Onza Pill straddler 

I'm happy with performance

towerscum


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## nato_the_greato (Feb 3, 2008)

I can only offer anecdotal evidence, but I had a Bianchi San Jose, terrible brake shudder. I popped the headset off, it wasn't faced. At all. I faced the headtube, the brake shudder went away. Bought a GT Peace 9er, same deal, head tube wasn't faced AT ALL from the factory, paint on the edge of the head tube. I put a 203mm rotor on it, and it shuddered terribly. Faced the headtube, it works perfectly now.

(Facing is using a special tool to cut the headtube so as to shave off the paint and excess metal, making the headset bearings parallel)

Working as a bike mechanic, I've seen a lot of bikes, some expensive, lots of cheap ones, very few of which had properly (or at all) been faced. 

Just my $0.02 and my own crackpot theory.


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## atpjunkie (Mar 23, 2002)

*buy a basic set of*



Mike T. said:


> So now I'm wondering if it might be a waste of money getting the highly-regarded Paul brakes. Maybe, to stop the shudder, I'll have to reduce their power to that of a $20 set of Tektros. But then I suppose _they_ would squeal enough to wake the dead.
> 
> I feel I'm entering a hornet's nest here.
> 
> Does anyone know of a set of el-cheapos that won't overpower the fork, are easy to adjust and don't squeal? Yes I'm aware that MFMV.


Froggleggs or Spookys
findYehstar Pads

done


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## shortcut_in_mass (Apr 23, 2008)

I have a 2008 Jamis Nova Pro with their stock carbon fork and it shudders quite a bit, which I've never experienced in any bike before. This thread has been informative and has relieved my initial fear that the fork may be headed towards catastrophic failure ... or is it? Is fork shudder dangerous in the long run or can you just put up with it? Could the fork suffer fatigue and just snap?


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