This nifty tool prevents accidental damage during piston resets.
What do you use to reset your pistons in your disc brakes? Big screwdriver, maybe a thin cone spanner or even a wood chisel, which was recommended by a member of MBR staff? These tools work, but you really risk damaging the braking surface on your pads or, if you remove those, the pistons themselves. There are dedicated tools for this job on the market like the Park Tool PS-1 disc spreader, but they’re only a small step up from a cone spanner and, if used incorrectly, can still put uneven leverage on the pistons. Birzman’s Disc Brake Piston Pusher is the next level because it’s an expandable spreader with two tabs that push on the pistons at the same time.
To use it you simply insert the two tabs between the piston (you’ll need to remove the brake pads first), swing out the handle and wind it clockwise. The tabs spread apart and push the pistons back into the bore, there’s no waggling needed or bracing the tool against the edge of the caliper, which could damage the finish.
I’ve used it on quite a few different brakes during testing, even on the trail, and it’s really effective. I did find on some SRAM brakes it doesn’t fully seat the pistons back into the caliper, but on everything else it just pushed the pistons with minimal effort.
The obvious question is, do you need a tool like this in your life? Unless you have a problematic brake, you may only have to reset the pistons two or three times a year when you replace the brake pads. And at £50 it’s not cheap. My take is that I think this a well-designed tool that is a real pleasure to use and it’s going to replace the Birzman Disc Brake Piston Press I have in my toolbox.
If you’re the sort of home mechanic that has a well-stocked shop and doesn’t mind splashing the cash on tools, or you have a bike or bikes fitted with expensive disc brakes and don’t want to mangle them, it’s a must have.