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"As I understand it, it's caused by the fork flexing and pulling the brake cable tighter, which in turn pulls the brake pads harder against the rim. I would imagine an alu fork would have to be pretty flimsy to flex that much."
Blimey you guys must have some flex in those forks to alter cable tension!
TBH I thought it was generated by the pads not correctly toed in. They start the judder as they prematurely grip and release (snatch), this gets amplified through play in the cantis and brake bosses, ultimately then violently flexing/juddering the forks.
Can't really see location of cable hanger causing or contributing to the problem
CR520 are £17 at CRC at moment - you might just need the front one - shouldn't have the same judder problems with the back one.
"As I understand it, it's caused by the fork flexing and pulling the brake cable tighter, which in turn pulls the brake pads harder against the rim. I would imagine an alu fork would have to be pretty flimsy to flex that much."Blimey you guys must have some flex in those forks to alter cable tension!
TBH I thought it was generated by the pads not correctly toed in. They start the judder as they prematurely grip and release (snatch), this gets amplified through play in the cantis and brake bosses, ultimately then violently flexing/juddering the forks.Can't really see location of cable hanger causing or contributing to the problem
You might not be able to see it but that is EXACTLTY the problem, try it. big bikes have always suffered with judder from the front end but if you move the cable hanger to the fork crown it vanishes.
"You might not be able to see it but that is EXACTLTY the problem, try it. big bikes have always suffered with judder from the front end but if you move the cable hanger to the fork crown it vanishes."
Sorry Guys but that sounds like a load of boollocks to me! 🙂
Any flex in the forks will be horizontal so will not pull down on the cable increasing brake pressure. Also what does the size of the bike matter?
Back in the days when mountain bikes had cantis brake judder still occurred if the brakes weren't carefully set up and toed in.
What about Magura's? They used to do road versions (HS66 & HS77) which come up on Ebay every so often - but I'm sure you could get the HS33 or HS11 levers to work - maybe 😕
As someone who got a cx bike quite late, and maybe isn't looking at things with traditional eyes I wonder how the " its racing, the bikes aren't meant to stop, ya choob!" comeback would work in other sports.
Would formula 1 be better with 1940's drum brakes? would descending off the Tourmalet be better in the TDF wth flexy single pivots? would downhill mountainbiking be more exiting? 🙂
Sorry Guys but that sounds like a load of boollocks to me!
Regardless, forks flutter back and forth, the steel forks on my tourer flutter alarmingly when the bike is laden and I break hard. When the pads are against the rim even tiny fluctuations in cable tension (from fluttering forks) can fluctuate braking effort sufficiently to set up a resonant frequency.
anotherdeadhero - Member
Regardless, forks flutter back and forth, the steel forks on my tourer flutter alarmingly when the bike is laden and I break hard.
Anyone wanting to do a bit of research on this just needs to ride an old steel track bike converted to the road. Most have nice skinny front forks.
Once they are fitted a front brake (which usually involves drilling a mounting hole) the full joys of brake judder can be experienced 🙂
Has anyone got any pictures of a fork mounted hanger the brakes?
I am fed up with my Tektro Oryx for same reasons, poor stopping and juddery fork and like Sanny I have moved over to Tektro CR720s (like 520s but with cartridge pads and a slightly different finish). Still to get delivered but on reading a few forums and talking to folk in the know it seems these wide canti's are the future (or is that the past as they are a bit retro!) - seems like this brake is best compromise between power and clearance for mud and rims.
As someone who got a cx bike quite late, and maybe isn't looking at things with traditional eyes I wonder how the " its racing, the bikes aren't meant to stop, ya choob!" comeback would work in other sports.
Would formula 1 be better with 1940's drum brakes?
but back to the OP and using yr analogy then using a cx like a mtb is like say using a le mans car for a rally circuit then complaining it keeps grounding
the full joys of brake judder can be experienced
Aye, its like ABS, but with more death.
Coleman - I'm afraid you are wrong, fork flex affecting cable tension IS the problem. I've cured a number of cross bikes using a fork mounted cable hanger...
"Blimey you guys must have some flex in those forks to alter cable tension!"
coleman, it's the same flex that stops you getting numb hands over the bumps, about 1/8" - 1/4" fore and aft is normal under pressure from most types of fork and that is more than enough to vary the brake pressure.
roter, just look at the Vapour on Genesisbikes.co.uk, it has one this year. we'll have stock of spares soon.
"Any flex in the forks will be horizontal so will not pull down on the cable increasing brake pressure. Also what does the size of the bike matter?"
1 - fork tip movement fore / aft has an up and down component as it moves in an arc, thf fork flex moves the brake in relation to the steerer mounted hanger
2 - size of bike matters as a longer head tube means a greater distance between brake and hanger, hence a bit more judder potential due to the cable being longer, but more of an issue is a bigger rider puts more weight on the fork and hence more flex.
coleman it's not all bollocks, it's a simple cause! ) but you're right that toe in can be an issue, it tends to set up a far higher frequency vibration though (length of moving part / variation causing the movement) and tends to cause squeal more than proper judder.
Sorry guys still can't accept this is the cause of the problem. I hear what you are saying but 10mm of flex at the fork tips will translate to less than 1.5mm of fore/aft movement at the bosses. Even taking into account this travels in an arc, the distance between hanger to brakes can only vary by much less than 0.1mm. With all the play in the system surely this cannot significantly increase pad pressure at the rims.
I still maintain incorrectly toed in and set up pads are the primary cause of the problem. They start the judder as they prematurely grip and release (snatch), this gets amplified through play in the cantis and brake bosses, ultimately then violently flexing/juddering the forks.
Many cross bikes cannot be fitted with fork mounted cable hangers as there is no hole at the crown
can only vary by much less than 0.1mm. With all the play in the system surely this cannot significantly increase pad pressure at the rims.
Regardless, this is the case. Its not the brake pads catching and releasing that causes the judder, you're right that this would not be enough alone to cause so much judder.
What it is doing is setting up a harmonic, a resonant frequency that just happens to be additative. The fore and aft flex of the fork matches the slight snatching of the wheel, which matches the resonant frequency of the frame, and so the judder gets bigger and the harmonic self perpetuates - until something changes, like a different setup or getting off the brakes.
Many cross bikes cannot be fitted with fork mounted cable hangers as there is no hole at the crown
You used to be able to get plates that fitted to the brake hangers, with an integrated stop, no idea if you can still get them.
Nicked from the Kinesis website.....
We have always lead the field in Cyclocross frame and fork design.
Now, our latest RC09 fork is way out front again with it's super lightweight, 460g monocoque construction and radical leading edge blade shape.
The optional brake hanger coupled to the advanced blade shape, allows powerful, judder free braking that is just not possible with other manufacturers, outdated designs.
The forged alloy hanger keys and bolts to a specially shaped crown and eliminates the need for a steerer mounted hanger. This serves two important purposes;
1. It does away with the long drop of inner cable between the top of the headset and straddle cable. In standard 'cross fork designs, minute changes in length caused by flex in the fork under braking, cause resonance in this area that leads to judder in some circumstances [mostly on harder surfaces with larger frames and riders]. The use of a crown mounted hanger completely eliminates this problem.
OMG! Uber noob pwnd 😆
"OMG! Uber noob pwnd" Ooer! that doesn't sound very polite.
Ok I give in. I'll surrender to the wisdom of the forum.
A couple of points raised on this thread;
"but more of an issue is a bigger rider puts more weight on the fork and hence more flex"
"mostly on harder surfaces with larger frames and riders"
makes me wonder if the problem didn't exist until lardy mountain bikers started riding cross bikes not for their intended purpose.Ho Ho 🙂
makes me wonder if the problem didn't exist until lardy mountain bikers started riding cross bikes not for their intended purpose.
waves but doesn't laugh 😉
ps edit - good post from the kinesis site
but back to the OP and using yr analogy then using a cx like a mtb is like say using a le mans car for a rally circuit then complaining it keeps grounding
really? a track car used off road? surely more like a non rally car on a rally course?
😉
The thing that I was trying to get across was that 'cross is the ONLY wheeled sport I can think of where having purposely poor brakes is seen as a positive, almost a badge of honour!. Now on some grassy flat courses crap brakes wont make any difference, but on more technical ones/ 3 peaks style events, having brakes you can have confidence in can only be a good thing right?
The fact that the serious riders often change bikes mid race 'cos their brakes are clogged up with mud shows that there's room for some improvement in design.
Changing bikes mid race - what, like road racing?
Cross is about having the lightest, fastest bike for a specific kind of course. Go to a European race and see just how fast they're riding round.
The 3 Peaks is a special race which really has no relationship to the rest of cross.
I'm not going to argue with Kinesis, they know best, but I've never ever suffered vibration on any of my cross bikes and I've always put that down to careful brake set up.
However.........
I did once suffer it whilst warming up, only to find that it was down to a slight buckle in the rim, changed the wheel and it went.
I have also noticed it with new pads and rims, but that was mainly with the old style rims without bare braking surfaces, but you could see clearly that it was the coating coming off causing the problem.
I'm curious to see if anyone is using fork mounted hangers at next weekends race.
I've got XTR v's on my Singlecross I've not had any judder.
Now I know why 🙂
I do get horrendous squeal if I don't line the pads up properly, though.
I cannot say that having terrible brakes is a badge of honour at all. The brakes are quite adequate, even good on my latest bike. I've been in races where people disconnect their brakes for clearance and just stopping pedalling is enough to stop you dead. It's daft to compare something like Formula 1 to that just because there are wheels involved in both.
Discs may well be a better solution but aren't allowed and them are the rules. Otherwise we'll continue to tweak equipment to get that advantage. Most riders are far more interested in tyres and getting more grip than the brakes, which says to me that most people are able to set their brakes up to be more than adequate.
Roter Stern - MemberHas anyone got any pictures of a fork mounted hanger the brakes?
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Tektro part number 1272AF
that's the one we use, it does the trick.
"makes me wonder if the problem didn't exist until lardy mountain bikers started riding cross bikes not for their intended purpose.Ho Ho "
there's some truth in that coleman! ) lardy or not, it's the change in use (and wider use) that has made a non-issue to 'cross racers become an issue to us lot.
back in the day, I remember the first time i rode on discs on properish forks, after going from avid sd5's on an indy c. I were going down the steep muddy rooty bit on the pink heifer and nearly went over the bars when I mashed on the levers. jumpers for goal posts etc.
Thanks for the pic mrmichaelwright! 🙂
Available from FisherOutdoor so any decent bike shop should be able to get them for you.
Ooer! that doesn't sound very polite.makes me wonder if the problem didn't exist until lardy mountain bikers started riding cross bikes not for their intended purpose.
Sorry, I was jesting with you.
This is def the case, I'll admit, but it also happens on my tourer when its laden with F&R panniers & kit too.
on the tourer i only get it with no front panniers
without panniers or with just rear bags it is terrible, so much so i shall not be touring on carbon forks again