Motorcycle Brake Discs Brake discs for motorcyles are subjected to extreme forces. So they must be replaced at the latest when they reach the minimum thickness specified by the manufacturer. At Louis you can buy brake discs form the world's leading makers. The Louis Bike Database shows you which ones are suitable for your machine. The most important things to bear in mind when changing your brake discs are explained in the Louis Tips for DIY mechanics. Remember: When you install new brake discs, it's best to change the brake pads at the same time.