How to check the thickness of a brake disc or rotor with a deep ridge

Checking the thickness of your brake disc or rotor? It’s a good idea to keep an eye on how they are wearing, particularly if you are using an aggressive brake pad type that causes more rotor wear than the OEM pads. It can be more challenging than usual to accurately check the thickness of a brake rotors whose pads have worn a groove in the center;

Here's how to check the brake disc or rotor thickness on a Hyosung GT250, GT250R, GT250V motorcycle using digital vernier calipers or a micrometer as shown on MotoFaction.org. These rotors have a ridge at the edge - making it a little harder to check!

As a side point, with most discs you can find out the minimum thickness somewhere on it – here stamped in the steel:

Here's how to check the brake disc or rotor thickness on a Hyosung GT250, GT250R, GT250V motorcycle using digital vernier calipers or a micrometer as shown on MotoFaction.org. These rotors have a ridge at the edge - making it a little harder to check!

Using a set of digital vernier calipers (eBay US, eBay UK, eBay AU) we can get a reading of the thickness of the rotor but in this case the ridge is too deep to measure the part swept by the brake pad, only the outer ridge:

Here's how to check the brake disc or rotor thickness on a Hyosung GT250, GT250R, GT250V motorcycle using digital vernier calipers or a micrometer as shown on MotoFaction.org. These rotors have a ridge at the edge - making it a little harder to check!

Most calipers have a cut-out in them to get around small ridges but if the ridge is too great that won’t help. In that situation you need to use a tool that can get around the ridge – we had a micrometer on-hand (eBay US, eBay UK, eBay AU) so that’s what we are using here. You can clearly see why it isn’t affected by the ridge:

Here's how to check the brake disc or rotor thickness on a Hyosung GT250, GT250R, GT250V motorcycle using digital vernier calipers or a micrometer as shown on MotoFaction.org. These rotors have a ridge at the edge - making it a little harder to check!

In this case we can see that there is about a 1mm measured difference between the two tools. In this case it is at least still over the minimum figure.

Here's how to check the brake disc or rotor thickness on a Hyosung GT250, GT250R, GT250V motorcycle using digital vernier calipers or a micrometer as shown on MotoFaction.org. These rotors have a ridge at the edge - making it a little harder to check!

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