Bicycles Stack Exchange
Bicycles Stack Exchange

Questions tagged [disc-brake]

Brakes with a disc called a rotor near the hub and calipers that squeeze pairs of pads against that disc.

A disc brake is a type of brake that uses the calipers to squeeze pairs of pads against a disc called a "rotor" to create friction. This action slows the rotation of a bicycle wheel, either to reduce its rotational speed or to hold it stationary. The energy of motion is converted into waste heat which must be dispersed.

There are two common methods used to actuate disc brakes on a bicycle: hydraulically or mechanically.

Hydraulically actuated disc brakes utilize hydraulic lines between the brake levers and the calipers. Mechanically actuated disc brakes use the more traditional brake cable to transfer force from the brake levers to the caliper. There are rare instances used in special configurations of a hybrid of the two actuations that use a mechanical brake cable to transfer force to the a hydraulic brake assembly located at the caliper area.

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Why/How should I bed in disc brake pads?

Why should I bed in my disc brake pads and what's the best way to do it?
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How to tell when disc brakes are worn?

How do I tell how worn my disc brakes are and what are the consequences of letting them wear too low?
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While on a ride, realised rear disc rotor was contaminated, what could I have done?

Last night, commuting, I got lots of dirty water all over my back brake (Promax Render-r mechanical disc), as well as on most of the rest of the bike, and me. I wiped the rotors with a clean rag to get the grit off, because light braking made an…
Chris H
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Why should the outside disc brake pad be closer to the rotor than the inside one?

According to this link, the distance between the inside, stationary disc pad and the disc brake rotor should be twice the distance between the rotor and the outside, moving disc pad. Why should the stationary disc pad be further away from the rotor…
user2670468
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Do mechanical disc brakes suffer from heat-induced fade?

The other day I read a question about heat induced brake fade in hydraulic disc brakes caused by too much braking on long, steep descents, which is something I have also experienced when cycling in the alps. (A quite unpleasant experience, I might…
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What does this piece do that came with my disc brake?

I recently ordered hydraulic Shimano disc brakes with rotors and they came with a bunch of hardware, including this piece: It looks like it would fit under the screws that secure the rotor to the hub: Does anyone know what I should do with it or…
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What are the negative consequences of not bedding in disc brakes?

It's common knowledge that disc brakes need to be bedded in. But I've never heard or found a description of what happens if you don't bed them in. Given the number of BSO's that now have disc brakes, and the likelihood that 99% of those never get…
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Having one wheel set with 6 bolts rotors and one with center locks?

I'd like to purchase a second wheel set for my bike: to have one wheel set for road, and one for cross/light MTB, and swap them easily depending on the kind of ride I plan. My bike uses 6 bolts disk brakes, but my local shop only has additional…
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Maximum Brake Temperatures

How hot does a bicycle disk get? I’ve been working on heat rejection for auto/truck disk brakes with some success. But the disk temperature needs to reach 700 degrees to be effective. This seems a bit toasty for a bicycle disk. Any thoughts?
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Is it normal that front wheel bends when front disk brakes are applied?

When I apply front disk brakes I see slight bend in the rim and wheel. Is this normal or I have a low quality parts.
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What are these rubber rings on my brake caliper bolts for?

I have purchased a disc brake adapter which came with a set of mounting bolts for mouting the adapter and the caliper together. The bolts have a rubber ring on them, but I'm not sure what it's for. Should it be mounted together with the caliper and…
user1049697
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Is there anything special about rotor bolts?

I fitted a new rotor to a new wheel yesterday (6-bolt) and didn't have any spare bolts so borrowed them from another bike. As I go to buy replacements, is there anything special about such bolts? I know they're generally Torx button heads, but I…
Chris H
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TRP HY-RD adjustment

Really struggling with these brakes now. Just installed new pads, but pistons won't separate far enough to put the wheels back in. Tried pushing the piston in using a plastic tyre remover, but no joy. It seems like one pad (hub side in both cases,…
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Avid BB5 asymmetrical pad rub position and squeal

I'm setting up some Avid BB5s. As I tried to bed in the brakes, the front one squeals quite heavily, the back does not. The following image is of the non-drive side of the front disc rotor. (Where the outboard pad hits.) The following image is of…
user34810
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Disc brakes sometimes sing

Sometimes my front disc brakes on my mountain bike "sing" when I am NOT applying them. The pictures show there is a space between the pad and the rotor. It can get irritating. Is there some kind of fix?
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