The Wrenegade Wrench: Disc Brake Bits

Setting up disc brakes probably isn’t anybody’s favorite activity, but there are some tricks and gadgets that can definitely make the task less onerous. Today we’re going to talk about a few tools that I find myself reaching for just about every time I work on brakes.

First up: the Park Tool PP-1 piston press.

Park is selling version 1.2 of this now, but I haven’t got the new version, so I can’t talk about it. What I can talk about is how long I put off buying a piston press, figuring that a plastic tire lever was good enough.

It wasn’t.

You simply push this thing in between your brake pads, and it spreads them apart. Evenly. No wiggling back and forth, as you’re forced to do with a makeshift solution like a tire lever. No scarring of the pads, which is absolutely going to happen at some point if you just use a screwdriver.

If you work on disc brakes, you should have a piston press. This is a good one.

Now that you have the right tool to push your pads into position, it’s time for the Birzman Clam.

This is a wonderfully simple piece of kit. It’s literally just a folded sheet of aluminum. To use it, first press the pistons to their fully open position using the piston press we just talked about. After you’re done that, loosen the bolts that hold your brake caliper to your bike frame and place the clam on top of the brake rotor.

Rotate the wheel until the rotor/clam sandwich is between the brake pads, inside the brake caliper. Now, squeeze the brake lever, and tighten the fixing bolts back up while continuing to apply pressure to the brake lever. Once you’ve snugged up those bolts, simply rotate the caliper forward, remove the clam, and you should be good to go.

Good to go! That is, if your brake mounts are faced correctly, your pistons are retracting evenly, your system doesn’t need to be bled, and your disc rotor is true. It’s just that simple.

Rarely. It’s rarely just that simple.

In reality, your brakes may well need to be bled, your pistons might not be retracting properly, your rotors probably aren’t true, and your mounts do need to be faced.

We won’t cover all of those today, but the Abbey Bike Tools Stu Stick will at least help you with the bent rotors.

Once again, this is a simple yet elegant tool. It’s a 4mm x 25mm bar of anodized aluminum with a slot (and a bottle opener) machined into it. Newer versions of the tool have two slots, but yes; I own an older, first generation example.

How does thing work? Just spin the wheel while it’s still on your bike, and observe the brake rotor/brake pad interface.

If the rotor wobbles significantly from side to side, you can now fix that. Slide the slot in the tool over the part of the rotor that is wobbling, and use it as a lever to crank the rotor over to the side opposite the wobble. Be gentle. Repeat as necessary until you have a rotor that is flat/true enough to allow you to depress the brake lever without the pads making intermittent contact with the rotor for the majority of their travel.

Try to avoid the temptation to make the rotor perfectly flat. That way lies madness. You’re just looking to make it true enough that it doesn’t “pulse” as you apply the brakes.

Lots of companies are making a tool like this these days, but Abbey was one of the first – if not the first to make a lightweight aluminum version. You will find these in a lot of traveling race mechanic’s tool kits (including mine) for just that reason. Bonus points for being named after Stu Thorne, for being only $22, and for including a bottle opener.

Last item today is from Prometheus lights.

This is the Beta flashlight and Flex Arm combo. Combining a AAA flashlight with an articulated mount that terminates in a magnet, this gives you a portable light source that will mount to any magnetically attractive surface. My eyesight isn’t what it used to be, and I find myself reaching for this more and more these days. It readily attaches itself to any steel bike frame, or steel part on a non-ferrous frame. When I’m working in an area without a convenient piece of metal to attach the unit to, I simply wrap this Magnogrip wristband around the frame and stick the light to that.

It turns out that it’s a heck of a lot easier to work on something like disc brakes when you can actually see what you’re doing.