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Mechanic’s Corner: Disc Brake Rotor Wear

We’re deep into the riding season, here in the Northern Hemisphere anyway. It’s time to consider the preventative maintenance that can keep your riding free of clicks, creaks and pops. In addition, wearable items are starting to see the effects of your daily mileage. To help maximize your Team Edition and Ride Prep Tool Kits, and any one of our premium bike repair stands, a couple of weeks back we took a look at the most common wear items today we’ll dive a little deeper. 

DISC BRAKE ROTOR MAINTENANCE

With the ever-increasing popularity of disc brakes (hydraulic and mechanical), one of the easiest bike maintenance procedures is to inspect disc brake rotors. This maintenance tip suggests a quick way to insure you are getting the best performance from your braking system.

WHY DO I NEED TO DO THIS?

Disc brake rotors endure a large amount of heat and friction on a regular basis. They can withstand large forces and are responsible for slowing our bikes down, which they do quite well. But as a result of these physical demands, it is a good idea to check them for wear regularly. Disc brake rotors will typically last through 2, maybe 3 pairs of brake pads (pad material and riding conditions influences this), but it’s never a bad idea to add a thickness check to any regular maintenance schedule. 

DISC BRAKE ROTOR MAINTENANCE – THICKNESS INSPECTION

Rotor inspection is easiest with the wheel removed because the minimum thickness standard is etched quite small on the rotor. This print is located on the outer surface and is presented something like  “Min. TH=1.5”. This is interpreted as “minimum thickness of 1.5mm”. Anything less than 1.5mm means it is time to replace (for this particular Shimano rotor). This measurement is not the standard for all rotors – for instance, Hayes is 1.52mm, Shimano is 1.5mm, Sram minimum disc brake rotor thickness is 1.55mm. However, these aren’t guidelines, but rather highlight the fact that there is no universal standard and looking closely at your specific rotors is crucial.  

Use your Feedback Sports Digital Calipers and measure the thickness at the braking surface, ensuring you have as much of the rotor braking surface within the calipers jaws (as seen). With such precise measurements, it’s good to check several points on the rotor, multiple times. 

If your rotors measure above the indicated minimum thickness then you’re in the clear. If your digital calipers measure below, contact your local bike shop (LBS) to purchase new ones. Your shop will have questions, so be sure to take note of your rotor size (140, 160, 180, 200, 203mm, etc.) , mounting style (centerlock or 6-bolt), and manufacturer of your disc brake caliper.

Since you’ve got the wheels out it is a good idea to double check your centerlock lockring or your rotor bolts for torque. The Team Edition Tool Kit includes the Bottom Bracket + Lockring Tool (which can manage standard and over-sized centerlock lockrings) and our Range Torque + Ratchet Wrench can handle 6-bolt, T25 torque specs.  If you’re replacing the rotors, be sure to face any writing on the rotor outward from the hub as pictured. 

Now that you’re confident you understand the mechanical status of your rotors, reinstall the wheels and get back to riding! Or replace them if needed, of course!

This simple check, and so many more to come, can be done with little mechanical experience. As we always say, with the right tools and a quality bike repair stand, anybody can service their bike.