HOW TO TELL IF YOUR DISCS ARE OKAY

If your discs are knackered your braking’s going to be compromised. There are a few different ways to check their health with the most obvious test being a good look around them. You can tell if a disc has had a hard life because it will be worn and scored. If you run your finger over a disc and it feels like a Braille version of God Save the Queen, chances are it’s pretty mullered. Just to be sure, get a micrometer on the case. Unlike a vernier gauge, a micrometer will allow you to measure the inner area of a disc, as opposed to the lip which is always proud as its unaffected by a brake pad. If it measures less than the minimum thickness stamped on your disc (or stated in an owner’s manual), it’s time to fit some new ones.

You should also check that the disc isn’t warped, which is visually recognisable. Get your bike on a paddock stand and give the front wheel a spin (easier when the calipers have been removed); if it looks wobbly chances are something’s not right. Double check by holding a screwdriver up against the fork so it barely touches the disc and as the wheel spins any warping will become obvious if the tip of the screwdriver touches one part of the disc only. It might be something as simple as dirt or paint on the mounting face where the disc attaches to the wheel, preventing it from mounting flush; so give that a check. If that’s not the case, remove the disc and put it on a flat plate. Wonky discs aren’t good because they push your pads back on a highpoint meaning it takes more pressure to get your pads in contact on the low point of a disc. You can sometimes see if a disc has a highpoint because it’s often discoloured through heat exposure, and you’ll be sure to hear it when you spin a wheel.