Weight Weenies

Hi all,
I'm running a Kinlin XR270 (laced to a WI H3 front hub, 20H with DT Revs) on a Specialized full carbon fork. I get brake shuddering at high speeds under light to moderate braking force. So I'm wondering, do I risk damaging the fork or headset bearings with this shuddering? I'm also concerned that I'm riding 3 Peaks - and there's going to be some gnarly descents which would require heavy braking. For safey's sake, do I need I rectify this problem by either getting the wheel rebuilt on a new XR270 rim, or borrow a Ksyrium front wheel off a mate?

Thanks

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If it doesn't happen with another wheel, I'd get the rim replaced. Plain sucks when the gear doesn't work as good as it's supposed to.

Try more pad toe-in before you do anything else.

What bike is it? What brakes?

Yeah, there are definitely a few things to check before you toss the rim.....1. Check your pad alignment. 2. What pads are you using? 3. Check your headset preload. Is it setup correctly? 4. Is the wheel out of true?

There are many things that can cause shudder.

A few yrs back I built up a wheelset with the kinlin xr270 rims and one of them had a shudder problem. After some research at the time, I found others having the same problem with that rim. I figured they had a bad batch or something. Mine was usable just a little annoying and has gotten significantly better with time.
If yours is like mine (usable) then maybe run some wet weather or more abrasive pads to smooth them out a little quicker. That might work.

Edit...another thing to double check is the brake nut. Make sure it's tight.

Also check the pivots of the brake arms themselves. They are adjustable, and excess play could make things worse.
You can stick a medium grit emery cloth between the pad and rim and rotate the rim a few turns, it helps clean up the machining ridges that can contribute to shudder.

Thanks for the helpful hints and replies everyone!
I tried my wife's Bontrager wheel on my CAAD and did some tests of feathering, medium and hard braking: no shuddering.... I'm pretty meticulous with the toe and alignment of my brake pads, so I know they're all good. All my bolts are tight and my headset is preloaded too.

Sounds like it's the dam rim's fault....

PS: I'm running Kool Stop black pads

Can you tell us a bit more about the set-up? What brake calipers are you running? How heavy are you? Have you checked the headset?

i had shuddering for the longest time and couldn't figure out what it was.

the things i checked were....

wheel truness
quick release tightness
brake toe in-ness
brake tracks

it was eventually.... headset looseness, due to a couple of reasons. Didn't have a microspacer at the time so the top cap was either not compressing the stem enough, so the headset was either binding, or allowing for too much play. Also my stem wasn't torqued enough allowing for a loss of compression.

The rim could just be bad but if you don't have a warranty you might be able to fix it. If you run your fingernail over the rim where the two ends are joined you will likely find a edge where they they don't perfectly align together. If you file or use a sharpening stone to smooth it out the shudder will be greatly reduced and as the rim wears it will gradually go away.

Check brake toe. The pads could also be glazed over which may cause resonation.

Geoff wrote:Can you tell us a bit more about the set-up? What brake calipers are you running? How heavy are you? Have you checked the headset?

Hey Geoff,
I'm running 2011 SRAM Red calipers with black Kool Stop pads - plenty of meat left in them. I'm a meagre 64kgs and my headset is all preloaded and the stem all torqued to 5nm...

Zen Cyclery wrote: Check brake toe. The pads could also be glazed over which may cause resonation.

Yep, I've checked the brake pads and they're toed in and not glazed

Pain999 wrote:The rim could just be bad but if you don't have a warranty you might be able to fix it. If you run your fingernail over the rim where the two ends are joined you will likely find a edge where they they don't perfectly align together. If you file or use a sharpening stone to smooth it out the shudder will be greatly reduced and as the rim wears it will gradually go away.

I thought the same thing, but the rim join is actually pretty smooth!

Thanks again for everyone's great suggestions. I think I'll just have to bite the bullet and get a new rim. I've read (just after I bought the rim to be built) that it isn't an uncommon problem. Would it pose any dangerous problems to my full carbon Specialized fork? I can see it flexing back and forth a bit under medium braking (That's 'flexing' not rattling due to loose headset )

Before you replace the rim/wheel, try some Yokozuna salmon pads/inserts. Whenever I've had a brake that would not stop shuddering, these pads fixed the problem.

u tried ur wife's wheel on ur bike

try your wheel on her bike

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