What causes brakes to pulsate?
03-22-07, 05:22 PM
#1
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What causes brakes to pulsate?
I'm just curious about what causes the pulsating of the brakes under relatively sever braking. I have noticed it on just about every bike I have ridden, many different wheelsets and many different brakes. What is the cause and is there an easy fix?
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03-22-07, 05:28 PM
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"Anti-Lock Braking System - Definition"
Definition: A braking system in which a sensor recognizes that a wheel is about to be locked up. The sensor sends a message to a computer, which starts releasing and applying the brake, stopping the lock up and allowing the driver to maintain control or drive around an obstacle instead of sliding towards it.
Definition: A braking system in which a sensor recognizes that a wheel is about to be locked up. The sensor sends a message to a computer, which starts releasing and applying the brake, stopping the lock up and allowing the driver to maintain control or drive around an obstacle instead of sliding towards it.
03-22-07, 05:33 PM
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could be lots of things. fork, flexy calipers, funky brake pads, braking surface, etc.
my spinergys make my front brakes pulsate when using ultegra pads. i not sure if it's the braking surface or the pad yet, though.
my spinergys make my front brakes pulsate when using ultegra pads. i not sure if it's the braking surface or the pad yet, though.
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03-22-07, 05:38 PM
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Flexy brakes will cause vibration. I was getting vibration and high pitched squeal with my Deore Cantilevers on my Axis. I replaced them with Paul Components brakes, and I've been braking in sweet silence ever since.
03-22-07, 07:26 PM
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If you're noticing this on almost every bike you ride, you're probably sensing a rather minute variation in the rim width. This can be due to the seam being thicker or thinner, or even the rim being sucked in slightly where the spokes pull at it. I wouldn't think you can feel the latter, but I can feel welded and machined seams on most wheels easily.
03-22-07, 08:00 PM
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Originally Posted by urbanknight
If you're noticing this on almost every bike you ride, you're probably sensing a rather minute variation in the rim width. This can be due to the seam being thicker or thinner, or even the rim being sucked in slightly where the spokes pull at it. I wouldn't think you can feel the latter, but I can feel welded and machined seams on most wheels easily.
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03-22-07, 08:08 PM
#9
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Originally Posted by EdZ
Its probably due to the fact that some spots on the braking surface are grippier, maybe less dirty than others.
BTW.......I'm grasping here.
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03-22-07, 08:20 PM
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Gremlins?
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03-22-07, 08:30 PM
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I don't usually brake very hard, but I sometimes notice what you seem to be talking about. My wild guess is that it's caused by unevenness in the braking surface (whether due to less than perfect homogeneity of braking surface thickness or due to a wheel out of true or due to something else) and in particular the weld in the braking surface being passed by the pads each time the wheel makes one revolution, with that unevenness right there causing the brakes to be a bit uneven. For what it's worth, I've noticed that my brake pad residue tends to build up on the trailing side of that weld in the braking surface, possibly because that weld gives the pads a place where they can dig in and get worn out at a disproportionate rate. It's not inconceivable that cleaning off that residue would cause it to feel worse until that residue builds back up to smooth out that region again.
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03-22-07, 08:56 PM
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03-22-07, 09:23 PM
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Originally Posted by urbanknight
If you're noticing this on almost every bike you ride, you're probably sensing a rather minute variation in the rim width. This can be due to the seam being thicker or thinner, or even the rim being sucked in slightly where the spokes pull at it. I wouldn't think you can feel the latter, but I can feel welded and machined seams on most wheels easily.
03-22-07, 09:24 PM
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Originally Posted by EdZ
Its probably due to the fact that some spots on the braking surface are grippier, maybe less dirty than others.
*obviously don't use acetone if you have carbon rims.
03-22-07, 10:27 PM
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I had Cane Creek SCR-5 brake calipers with KoolStop (black) pads and on a set of Ksyriums they would chatter in the back when I braked hard. I swapped the calipers and pads out for Ultegra all around and haven't had a problem since.
03-22-07, 10:51 PM
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Originally Posted by Ryleeryno
My pulsating brakes were causing by a faulty headset.
03-23-07, 01:10 AM
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Originally Posted by the beef
Possibly an out-of-true wheel?
03-23-07, 11:35 AM
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I never noticed it. Either it is smooth or is totally locked up.
