fork judder

just built up a columbus xwing and the front fork judder is terrible.

 

Anyone got a similar bike and solved a similar problem? (or just tips to solve it generally!!)

 

ta

 

Avid CR520 brakes on a carbon columbus fork, BTW

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Permalink Reply by Matthew Webber on January 23, 2012 at 20:04

If you can add a fork mounted brake hanger, that ought to do it. My fork was already drilled. Yours may not be...

Permalink Reply by Grant Thomson on January 24, 2012 at 13:00

cheers matthew - pretty sure the fork isn't drilled - think it's full carbon unfortunately.

Permalink Reply by barry davies on January 24, 2012 at 14:41

are the front brake shoes toe-ing in correctly ????

try some 'softer' compound front pads, had a friends carbon forked X bike and it was terrible for shaking but reset the front toe-in and fitted softer pads and was ok...

might help if you cannot fit a fork mounted hanger

Permalink Reply by Grant Thomson on January 24, 2012 at 14:43

OK, thanks Barry will give that a try

Permalink Reply by Neil Mansfield on January 24, 2012 at 17:34

Try these babies if adjusting is difficult...

http://www.zepnat.com/component/page,shop.product_details/flypage,s...

Adjust-tastic and eliminated my judder.

Permalink Reply by Greg Keller on January 24, 2012 at 18:14

Fork shutter sucks. Some forks are worse than other as well due to their make up. Indeed per comments above, toe-in of the pads is critical and helpful (I literally had to bend the (brake) posts on TRP Magnesium's (be careful not to bend your fork's brake post or the brake arms themselves). TRP makes aftermarket pad holders as well that have a toe-in capability.

Another key factor to combat shutter is how high you hang the straddle hanger/cable. Some of the shutter is actually due to harmonics in longer front brake cables...in that the cable begins to reverberate...pulling subtly on the hanger/straddle and thus starts to literally shake the brake arms....causing micro 'releases' of the brake pad against your rim. It then escalates quickly and before you know it your fork is shuttering like mad. A trick is to bring the cable hanger up higher (shortening the amount of exposed cable seen between the top hanger by your stem and the straddle hanger. You will need to adjust the length of straddle cable too (longer). This often helps the shutter considerably and has side effects too like opening up the arms wider to drop wheels out quicker for changes. The amoun of pull though is still OK in that the adjustments you'll make won;t make the brakes 'looser' per say and less powerful. You'll see what I mean when you set it up. 

Note Sven's ceble straddle height here:

http://cyclephotos.co.uk/2012/01/world-cup-8-hoogerheide/#!prettyPh...

Hope this helps!

Cheers from Boulder

Greg

www.mudandcowbells.com

Permalink Reply by Steve Smales on January 25, 2012 at 19:01

Try properly torquing the headset bearing preload. I had dramatic results after spending a fortune on pads/brakes etc. You'll need a low range torque wrench as it needs 3-4 NM

Permalink Reply by Grant Thomson on January 26, 2012 at 9:54

thanks all.  will have a tinker about with it at the weekend and see what helps

Permalink Reply by John Parkinson on January 31, 2012 at 16:49

Hi Grant

I have the same bike/fork and brake as you I guess, and got so frustrated with the judder and associated faffing I ended up doing this V-brake and Travel Agent conversion:

 

 

It looks a bit Heath Robison in this photo and has since been upgraded to XT, and tinkered with a bit, but works a treat.  I haven't had any clogging issues worse than standard cantis so am pretty happy.  I won't go back to cantis.  I use my bike a little on the road, and the judder was very scary.

NB this set up - for what ever reason - didn't seem to work so well on the back so stuck with cantis there.

 

Hope this helps

 

Cheers

 

John

 

 

Permalink Reply by Grant Thomson on January 31, 2012 at 17:01

thanks John.  Yup, the judder is horrendous on the road - feels like the headset is totally loose but it definitely isn't.

Permalink Reply by Tony_J on February 4, 2012 at 14:33

I went over to mini-v's from canti's and that helped a lot, prob because i got sick of constantly having to tweek the cantis

i still get some judder, when turning hard for some reason, but its nothing like it was.

as stated above a decent set of pads with a decent brake-holder that allows fine adjustment is also a good direction!

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