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Short: What mechanisms are relevant to the production of that noise and what are their parameters?

Up until a couple of years ago, I had only ever heard a quite, low, rubbing sound when the tires skidded on asphalt.

That was all on relatively standard sized tires (i.e. 28") and bicycles (i.e. upright non-folding or anything).

Now on my recumbent with 20" wheels when I brake sometimes I hear a loud screeching sound like on a car.

This happens when the wheel is skidding (i.e. speed difference of tire and ground somewhere between 0 (excluding) and forward speed), but not locked up (i.e. wheel not turning at all, speed difference of tire and ground equals forward speed). If it's locked up completely, then the sound is the quiet low rubbing noise I'm used to.

I haven't been able to pinpoint exactly what causes the different sounds. Maybe it's the asphalt type (new one seems to promote screeching?), pressure (lower=more?), wheel size (smaller=more?), wheel width (wider=more?) or braking technique (the noise mostly seems to appear when I get it just right and am only almost skidding).

What I can say is that I've been riding disk brakes for years and those specific disk brakes for some fewer years. I have readjusted them, changed pads, had annoying noises appear, made them go away again. This never seemed to change the screeching noise I described above.

  • Quick guess: on a upright, the rear wheel is partially unweighted when it skids. This is also true on a recumbent, but to a lesser extent. – Paul H Apr 23 at 22:35
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    I'm going to guess that you have disk brakes. – Daniel R Hicks Apr 24 at 1:48
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    @DanielRHicks I do, but I'm really 99.99% sure it's not the disks - the same sound has been accompanying me through all of my disk pads and brake adjustments. What really changed it was going from 406-47 to 406-42 (I hear it less now) and when I had 406-42 with spikes on I never heard it at all. – Nobody Apr 24 at 10:00
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    So, the things that have changed for you to notice more strident screeching: you brake dominantly with the rear wheel, and you have disk brakes. Now the question that comes to my mind is: do you lock up your wheel often? If so, why? – Gabriel C. Apr 24 at 12:53
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    @Nobody If there's tire screeching, you're skidding. If there's skidding, the wheels are locked. If the wheels are indeed not locked, then it's not your tires that are screeching. – Gabriel C. Apr 24 at 14:42
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The screeching that you describe is unlikely to be caused by the tyre skidding. It's more likely to be the contact between the brake pad and the braking surface causing the sound.

On an alloy-wheeled rim-brake setup, this is the rubber pad rubbing on the rim. If it's squealing, then it could mean that the surface of the pads has picked up some shards of the brake track and is scraping them on the brake track.

On a carbon-wheeled rim-brake setup, this could just be the standard sound. Some carbon wheels are just loud under braking and there's nothing to be done.

On a disc-brake setup, this could indicate that the pads are contaminated, requiring replacement. If the pads are sintered, then like the carbon wheels with rim-brakes, there's only so much you can do. Sintered pads are just known to be a bit noisier.

In any of these types, worn-out brake pads can also cause a screeching sound. If this is the cause, then you just need to replace the brake pads.

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    I don't think it's the brakes. They are usually quiet and if they are not, the sound of the sintered pads on the metal disks is really different from the tire screeching sound similar to that of cars that I described. Besides, the brakes are always the same no matter what I'm riding over or if I'm close to losing traction or not. If it was the brakes I should always hear it when braking hard. – Nobody Apr 24 at 10:05
  • @Nobody My experience in mountain biking is that one minute my brakes might squeal like crazy, then the next, they're silent. Grit, water, etc. have definite effects on brake noise that come and go. – Gabriel C. Apr 24 at 14:48
  • @GabrielC. True, but I ride almost exclusively on asphalt. If I was riding offroad I would agree completely. – Nobody Apr 24 at 14:54
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I've heard a wide variety of tire skidding noises over the years. From almost no noise at all to high pitched screeching as you describe.

There are a variety of factors that come into play when creating this sound that all relate to the frequency of the sound resulting from a tire sliding over a surface.

  • Tire composition
  • Tire dimensions
  • Tire pressure
  • Road surface composition / texture
  • Load / weight on the tire
  • Temperature
  • Other?

I was unable to find any studies explaining what parameters would cause differences in skidding sounds. I am unable to draw any conclusions concerning the parameters that would drive different frequencies based on my observations.

We do know that if a vehicle is skidding vs. controlled braking the skidding vehicle will take longer to stop. The information in the linked article is for cars but the principles apply. If a rider uses both front and rear brakes correctly maximum braking effect is gained. Sheldon's advice on using both brakes is helpful.

Skidding also causes tires to prematurely wear out.

So, whatever sound your tires make and for whatever reason that particular sound is generated, if you are skidding you could be saving money and stopping better by braking correctly.

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