If you’ve ever experienced noisy or howling hydraulic disc brakes on your cyclocross bike, this week’s Mechanical Monday solution costs a few cents, takes just a few seconds, has saved some custom builders thousands of dollars, and will help you stop pulling out your hair in attempt to quiet your bike. Sound too good to be true? Don’t judge yet.
There are many factors that could cause howling disc brakes, such as rotor or pad contamination, improper setup or a bent rotor. Hydraulic disc brakes add another layer of complexity, with resonance being a factor when the hydraulic line and frame vibrate under braking load.
If you’ve replaced your pads, cleaned your rotors with isopropyl alcohol and followed our tips on properly adjusting a disc brake, and the howl or screech still persists, it’s time to take a look at your frame.
Do you have a hydraulic hose that has a bit of slack in it? Or have a stretch of hose, more than eight inches or so, that could use an extra clamp to the frame? Or hydraulic hose guides/clamps that don’t have a tight grip on the hose, allowing the hose to rattle? Turns out, the hydraulic hose could be vibrating under braking, and at a certain frequency, the vibration wreaks havoc on the hydraulic system, pulsing the brake and causing that dreaded, embarrassing howl.
A telltale sign that you might suffer from this problem is your brakes howling only at certain speeds and braking loads—typically going down steep hills in our experience. Some call the howling noise disc brake squeal, screech, or even a “turkey warble” sound.
The Solution: Zip Ties
That’s right. A simple zip tie or two can eliminate this dreaded howl.
Take the zip tie, and cinch the hydraulic hose to the frame wherever it’s not already clamped securely. In the case of our test bike, this was about six inches above the brake caliper on the seatstay. Cinch it down, cut off the excess zip tie and be sure the head is positioned in a way that it won’t cut your leg or ankle.
A simple fix to hydraulic brake resonance: a zip tie © Cyclocross Magazine
Skeptical? Check out the video below and see the results yourself ( be sure to turn the volume on, if you want to hear the before and after).
We at Cyclocross Magazine have used this Mechanical Monday trick successfully to quiet rear braking on two bikes, of different materials and brake brands. One bike, with SRAM Force hydraulics, as seen in the video, could have benefited from an extra clamp, while another (carbon with Shimano RS785 hydraulic) had a zip tie on a guide break loose, sending wildlife for cover every time we hit the downhills. It wasn’t until a post-ride bike check revealed the culprit: a missing zip tie that need replacement. Replacing the zip tie instantly eliminated the noisy, squealing disc brake.
While we don’t suggest that this tip is a fix-all for all disc brake noise, it certainly solves loud disc brake resonance due to hose vibration, and it’s been validated outside of our offices. We shared this tip and experience with the folks at Calfee Design, who were working hard on new carbon fiber designs to stiffen and reinforce their disc brake caliper mount to reduce disc brake howl and squeal. Our mind-blowingly simple solution solved their disc brake noise issues, and thankfully scrapped a frustrating, costly engineering project.
Hat tip to Christian Parker of Menlo Velo Bicycles for this solution. His shop was stumped by a customer’s noisy bike, and had to rebuild and replace an entire rear triangle on a full suspension bike before stumbling across this simple fix that literally cost less than two cents. Others have used tape as a quick, less-permanent fix.
Have a riding buddy with embarrassingly noisy hydraulic disc brakes? Share this article, or better yet, bring a few zip ties and a clipper to your next ride, and enjoy riding with him or her in peace.
For more bike fix tips, see our other Mechanical Monday articles here.
