Having issues with some of your brake pistons not moving properly? If so, you could be leaving significant brake performance on the table. Luckily, it’s a fairly simple thing to fix if you’ve got the right tool.

These tool's can be used on a variety of 2 and 4 piston brakes.

The tool constrains all but 1 of the pistons so you can get the stuck piston moving with ease. Just drop the tool into your brake, pull the brake lever and hey presto, the stuck piston will move. Clean the piston with a cotton bud and gently press the piston back into the brake caliper with your tyre lever. If you want to clean them all, push them all back with your tyre lever and do them one at a time.

Put simply, this tool makes it easy to advance a brake piston as far as possible without popping it completely out of the caliper. This allows for as much of the piston to be cleaned as possible, which helps you maximise your braking performance.

The tool looks a bit odd, but between rotating and flipping the tool you can extend any brake piston. It also has a chamfer on the leading edges which makes it easier to insert in your brake caliper.

We promise that the tool doesn't look nearly as bad as the product image, we just have been without photography resources recently and wanted to list it anyway.

Cleaning procedure:

Carefully push all pistons back into the caliper using a tyre lever
Insert this tool. Put the retaining pin through the tool and caliper to keep it in place
Pump the brake and watch that the piston on the side of the tool with the cutout extends
Stop once the piston hits the tool - feel free to grab the brake lever a few times
Remove the tool
Clean the sides of the piston - we use isopropyl alcohol and cotton swabs
Push the piston back into the caliper with your tyre lever
Repeat with other pistons
Optional - apply a droplet of brake oil to the piston surface before pushing it back in. Only do this if you are going to douse the caliper with alcohol to clean it after the procedure, you don't want any residual fluid hanging around!

While it is possible to perform this job on 2 piston brakes by carefully constraining 1 piston with a plastic tyre lever and pulling the brake lever, this tool makes it a whole lot easier and ensures you don’t pop the piston right out of the caliper.

Piston Release Tool for 2 and 4 Piston Calipers