Front brake shudder
Ever have it? You enter a turn and grab some brake to strip off a little speed and your fork starts pulsating like a jackhammer and you contemplate ditching for a drop-tuck-and-roll. It can be scary. The good news is you might find something in here that will fix it.
If you have no idea what I am talking about, set a book mark now so you can come back to this if/when you do experience it. It can be a very frustrating thing to deal with and fix. Some (perhaps all) of this stuff will seem basic to you, but if you follow these steps you should get closer to eliminating the problem.
1. Make sure *everything* is tightened properly (you do know that "properly" means don't you?...think torque wrench). Check the headset, the brake mount, and every pivot point in the front brake. If it is a cantilever brake, the mounting posts are pivots and if one has more play than the other...it will pulse/shudder/hammer like a jackhammer. You may have to use shims and a torque wrench to get things right. You may also have to replace your posts (if you can not recall the last time you did, start with some new studs/posts). If you have brakes that have non-user serviceable pivots, proceed to the next steps playing very close attention to #4)
2. Get the correct compound brake pads. If you are using a softer compound than your conditions require, you will place undue burden on your brake components to make up for the mis-application (namely your pivots). If you have a very well tuned brake system you will never know that you have the wrong pads for your conditions, but if your pivots loosen or become worn, you will learn what I am talking about.
3. Make sure that you have adequate toe in on the pads. If you are unable to get #1 done correctly, you may *reduce* the problem with HUGE amounts of toe in, but as it wears the problem will return. This solution is not ideal, but may have to be used in a pinch.
4. Make sure you have the brake manufacturer on your side.
This problem has been getting under my skin (somewhat literally) for a while. I tried everything I could imagine. Ultimately, I called the maker and put the turd in his pocket. In all honesty, I contacted them for suggestions long before I ran out of ideas. After I tried everything I could think of (and followed the manufacturer's suggested remedies) I returned them for consideration.
Once they received my brakes, they tested them and swapped them for brakes that were freshly rebuilt (new springs, pivot bushings, pivot shaft, and some other slop-reducing stuff). Perhaps in an ideal world they would have rebuilt mine and sent them back, but I was somewhat hasty with them. I begged them to prioritize my situation since I do not have a set of backup brakes. I should receive them back tomorrow...I will let you know how that works out.
Some more info
I received my brakes back from the manufacturer along with some advice. I re-installed the calipers and took the bike for a ride only to find that the shudder was diminished, but still present.
I called the company and they put me in touch with a mechanic for a big pro team (this was a neat opportunity). We discussed some probable causes. When I get this whole thing resolved I intend to discuss the level of customer service this company is providing (among the best I have dealt with).
He suggested that my headset spacers were not perfect allowing a slight side load to the headset (he also wanted to be positively certain that the headset was tight). When we discussed that the headset, and spacers were replaced (following my crash), and the problem did not change, we decided to rule the headset and spacers out.
Through our discussion we also determined that the problem could be related to the rim braking surface. The rim was new and had deep machining. Perhaps the surface allowed for so much friction that as the bike slowed, the kinetic friction was being overcome by slip-stick friction as the front wheel approached lockup?
The test was to use an alternate wheel. With the alternate wheel, the shudder was much less (but still present). Conclusion, the wheel is PART of the problem.
I also tried installing a much heavier caliper not known for being ultra light, but is very overbuilt and does not flex much at all. Even with the heavily machined rim, there was no shudder. Conclusion, there are many factors that contribute to the problem, but eliminating as much flex as possible in the brake system goes a long way toward solution.
I think the answer to my problem may be that I am a little too heavy/aggressive for ultra light brakes. If I were to not brake hard at times, perhaps I would not notice this problem.
In the end, I like to ride the way I do, and I am not willing to change to accommodate parts (I believe the machine should fit the rider's desires, not the other way around). Perhaps I need to try some slightly heavier/beefier brakes...hopefully this manufacturer will help me out with this concept...I will keep you posted.
shudder
have you tried cleaning the rim braking surface with brake cleaner or simple green?
Thanks
Yes I have. The wheels are a new build, so one of the first things I did was clean the spoke prep/fingerprints from the braking surface.
Toe-in & brake pad compound
Both toe-in and brake pad compound solved my problems. I was running a compound that was too soft. All of the other fixes were addressed, but I was getting so much jackhammering I thought it was going to snap the carbon steerer tube on the cross bike. Now there is none. Good tips.
Boz, what rims are you using?
In my case the braking surface of the rim is a big component of the problem. If I were to ride in sloppy CX conditions for a while, the abrasion to the rims would probably result in two things: Less stopping force, and less brake shudder.
I think the CURE in my case is to further break in the brake surface, and switch over to stiffer components that are perfectly set up.
Which caliper brake?
Interesting post I have the same problem on a Masi CX. I am curious - which 'much heavier caliper brake' did you fit? (brand/model). This may help with my prob!
Shimano Dura Ace
I tried many different calipers on this application. The stiffest was the Dura Ace caliper, but I am currently using a custom built version of the Ciamillo Negative Gravity Ti.
Toe in fixed it for me
I had the same problem develop. I first thought it was due to an out of true wheel- but that didn't fix it. I tightened the brakes (fixing bolt and the one on the caliper, as well as the shoes) and toed in the shoes carefully. Much better! Still some slight vibration in the fork, but I believe this is due to minor variation in the rim surface.
Same problem
A couple of weeks ago, a friend of mine, who I respect as an experienced bike mechanic, took my '99 Fuji Team for a much needed "overhaul". After he tore it down, he told me what replacement parts I needed and I ordered them Online. Finally got my Fuji back yesterday. Took it for it's first ride since the "overhaul" and Booo...when the front brake is applied the front end shudders like a dog s__ting peach seeds! Spent most of the morning over at Jim Shipp's house, trying to figure out what was happening. Headset fine, brakes work, but makes the front wheel rapidly shake so much it almost shook my Livestrong bracelet off! We put on another wheel that he said was a good one, but that wheel had a high spot that mostly "bumped" in one spot, without too much shaking. So that test was inconclusive. Big mystery, which we can't really figure out, but my money is on the fact that when he rebuilt the wheels he switched the rims out. He took what had been the rear rim and made the new front wheel from it and the same (opposite) for the front rim. Follow? Me neither. I think he maybe put the new front wheel together so that the rim is now rolling in the opposite direction then it did when it was the the rear wheel. He had no logical explanation for doing that. I'm thinking, with those rims being 10 years (and maybe 45000 miles) old they've had plenty of time to become "set in their ways" , if you get my drift. He had also installed a different pair of brake pads on the front (not new, but in like new condition). I took them off later this afternoon and replaced them with a brand new pair. Didn't make any difference...the front end still has the shakes. Got any ideas?
There are lots of ideas posted
You have read the post I am sure, and perhaps you have explored all the possibilities I mentioned in there.
I have heard of poorly set headset cups causing this, bad bearings in the headset, incorrect toe in of the front brake shoes, sloppy (loose) brake calipers, wrong compound friction material, flimsy fork legs or steerer, improper headset pre-load, and even improperly faced frames. Many of these are possible on your bike.
I could write a book on what *helped" my situation, ultimately all my efforts only *reduced* the problem until I put on a new front wheel. I am still working on answering the question regarding what exactly it is about the old wheel, but I am fairly confident that there is a minor defect in the brake track.
I would assume that every case is different, but the FIRST (and easiest) thing I would recommend you try is a front wheel that is KNOWN to produce good results on other bikes. For me it was a classic 32 spoke 3x build with a Mavic Open Pro rim. I am not saying that this wheel is ideal, but lets face it, it makes no compromises in the name of light weight! Good front wheels are plentiful, surely someone near you has a good solidly-built wheel they will loan to you for an afternoon.
All this said, cantilever brakes are somewhat notorious for this problem. The location of the cable hanger relative to the brake is significant. Closer is often better as it allows for less input form fork crown/steerer.
Regarding your rim direction being possibly reversed. What prevents you from simply opening the skewer and turning the wheel around? For what it is worth, my problem did not change at all when I reversed my rim rotation direction, but it went away entirely with a new wheel.
Ugh...same shuddering problem w/ cantilever brakes
So far, this shudder problem has stumped two reputable bike shops! I installed new pads, and it did nothing. The mechanic thinks that the "play" where the brake lever attaches to the fork (brake boss?) is the problem, but he didn't have time to play around with it.
Thanks for writing this blog post, allowing feedback and discussion. I will try another wheel, to start.
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