Posted at: Feb 12, 2023
If you hear a strange "shuffling" noise coming from the disc rotor area of your disc brake bicycle, it could be disc rotor distortion. This section summarizes why disc rotor distortion occurs and how to correct the distortion.
Table of contents
Sponsored Link
Disc brakes on road bikes, MTBs, and other bicycles are designed to brake by tightening the rotor, which rotates around the hub, with a caliper. Disc brake installations set the position of the pads on the caliper “to match when the disc rotor rotates in a straight line, not touching from side to side.
On the other hand, if the rotor distortion occurs, the rotor will rotate swaying from side to side when viewed from above. As the rotor swings from side to side, the distance between the rotor and the caliper pad changes, causing the rotor to rub against the pad even when the brake is not closed.
If you hear a strange “shuffling” noise coming from near the rotor, it is evidence that the pads and rotor are rubbing against each other. In this case, it is safe to assume that the rotor is distorted.
Since the disc rotor is a sheet of metal, it will bend and distort if a large force is applied to it from the left or right.
Large force is a case-by-case basis, but even hitting something against the rotor when replacing a wheel or a strong impact on the rotor when falling off a car can cause the rotor to distort.
Conversely, unless a large force is applied, rotors rarely distort spontaneously.
Distorted rotors mean that the pads wear out faster because the pads and rotors are constantly rubbing against each other at regular intervals. In addition, the pads will have an unnatural hit on them, so when they are replaced with different rotors, there is a possibility that the hit will not be firm.
If the brake pads do not hit the brakes properly, the braking power will naturally be reduced. Since the ability to brake firmly is directly related to the ability to ride a bicycle safely, riding with a distorted rotor is a major problem.
Also, as explained earlier, a distorted rotor will cause abnormal noise. It is not good for your mental health to run while listening to the strange noise all the time.
It is not possible to check if a disc rotor is distorted just by a quick glance from the outside.
To check for warped rotors, you should
The following methods are the easiest to use. If the rotor rotates in a straight line, there is no problem. However, if the rotor moves left or right, there is a possibility that it is distorted.
Since the rotor is a sheet of metal, it can be corrected to some extent by applying force in the opposite direction of the distortion. Since most bicycle rotors are thin, correction can be done by an individual.
The best way to do this is to use a special tool for rotor correction. With the special tool, it is possible to bend the rotor from the root so that it can be properly corrected.
If you do not have a special tool, you can use a monkey wrench at home. However, since the correction cannot be made from the root of the rotor, it may not be possible to fully correct large distortions.
The procedure is as follows. 1.
If you do this with full force, you risk damaging the rotor, so bend it lightly with a few “kukkuks” using small force.
Repeat this several times, and when the noise stops, the correction is complete.
New disc rotors of higher grade are expensive, but middle grade or lower disc rotors are not that expensive.
If you are not able to correct the disc rotors by yourself, or if it is too much of a hassle, replacing the rotors is an option.
Disc rotors are sold at low prices at flea markets and auctions, but most of them are sold by amateurs who do not check the decrease and distortion of the rotors.
On the other hand, used bicycle stores that specialize in bicycles basically check rotors for wear and distortion (if not checked, an explanation is provided to that effect), thus preventing problems with distorted rotors.
Since rotors are part of the brake system and a safety-related part, it is best to prioritize quality over cheapness.
Sponsored Link
TPU Inner Tube: Features, Pros, and Cons for Road Bikes and MTB
TPU inner tubes are gaining attention as the third force in bicycle tires. We summarize its features, advantages and disadvantages of using it on Road bikes and MTBs, and major manufacturers.
Shimano Mechanical Brake Levers for MTB and Hybrid Bike
Shimano mechanical brake levers are now few and far between. The following is a summary of the current model lineup, specifications, and compatible components.
Summary of electric components for MTB
This section summarizes the types of electric components for MTB and the advantages and disadvantages of each.
MTB Dropper Seatposts: Types and Considerations
The dropper seat post is becoming a "must-have" part for MTB. Here we summarize the lineup, specifications, and features of dropper seatposts for MTB from major manufacturers, as well as a comparison of each manufacturer and points to consider when choosing a dropper seatpost.
SRAM Component Grades and Compatibility Summary for MTB
This section summarizes the grades, features, and compatibility of SRAM's Eagle series of components for MTB, as well as the electric component AXS and the latest component, Eagle Transmission.
Choosing SRAM MTB Sprockets: Compatibility and Key Considerations
SRAM components are being increasingly adopted in entry-grade MTB. In this issue, we summarize SRAM's sprockets for MTB and points to consider when choosing one.
12-speed sprockets for MTB compatible with Shimano Free Hub(HG spline)
We have put together a 12-speed sprocket that is not part of Shimano's 12-speed lineup for MTB. With this one, it is possible to convert to 12-speed with a conventional Shimano Free Hub (HG spline) without upgrading the wheels.
MTB suspension fork interchangeability standard! You definitely want to check when replacing.
When it comes to serious MTB customization, suspension fork upgrades are the way to go. However, there are various standards for MTB suspension forks, and if you choose the wrong one, it may not work at all.
Shimano MTB sprocket and wheel compatibility summary
This section summarizes the compatibility of Shimano's sprockets and wheels (free bodies) for MTB, which are a mixture of old and new standards, the latest Micro Spline and the previous HG spline, and what to look out for when purchasing.
MTB End Standards: What to Consider When Buying
Detailed explanation of MTB end standards! What is the boost standard? What is the end width that fits your MTB, points to keep in mind when buying an MTB, etc.
MTB wheel standards and how to choose one without fail.
The following is an overview of MTB wheel standards, their compatibility, and how to choose the right wheel for you.
What is a Tire Insert? Advantages and Disadvantages
This section summarizes what tire inserts are and the advantages and disadvantages of using them, which have been attracting attention along with the spread of tubeless tires and have recently been used in professional road racing.
Shimano disc brake pad types and compatibility
This section summarizes the types of Shimano disc brake pads, the differences between models, and compatible brake calipers.
TPI, Compound, Tread? Understanding Bicycle Tire Specifications
When looking for items to upgrade your road, MTB, or gravel bike tires, technical terms such as TPI, compound, and pattern appear in the descriptions. At first glance, tire specifications may seem difficult to understand, but if you keep only the important details in mind, your tire selection will be enhanced.
Torque Wrench: Advantages and Disadvantages of Torque Management
A torque wrench is a useful tool to have if you want to properly maintain your road bike or MTB. The following is a summary of what a torque wrench is and the advantages and disadvantages of torque management.
Perfect Guide: How to Raise Tubeless Tire Bead
Bead raising is an essential task with tubeless tires. However, there are times when it is easy to raise the bead, and other times when it does not raise at all despite your best efforts. In this issue, we will introduce a method to raise the bead of a tubeless tire that will not raise, considering the cause.
Tubeless Booster and Air Pumps with Booster: Pros and Cons, how to choose
The booster simplifies bead raising, which is the most difficult part of tubeless installation. We have compiled a list of air pumps with booster(boost functions) that are reassuring to have one.
Hookless Rim: Advantages, Disadvantages, and Considerations
Many "hookless rim" wheels are lightweight and cost-effective. What is hookless? We have compiled a list of advantages and disadvantages of hookless, as well as points to keep in mind when choosing.
What is the ASTM standard for bicycle wheels?
What is the ASTM standard for bicycle wheels? We have compiled a list of points to note when choosing a wheel.
How to Handle Flat Tires with Tubeless and Tubeless-Ready Tires
Tubeless tires have seen a dramatic increase in the number of users over the past few years. Even with tubeless and tubeless ready tires, punctures cannot be reduced to zero. The following is a summary of the causes of punctures and how to deal with them.