Replacing pads on a TRP Spyre mechanical disc brake caliper

I’ve had the fortune of owning my TCX SLR 2 since May 2014, and the bigger fortune of having it come stock with TRP’s Spyre mechanical disc brakes. Around that time, very few people in the Philippines bothered with the Spyre, let alone any mechanical disc brake, on a road bike. TRP’s twin-piston anchors proved a massive hit, generally being lauded as the best mechanical disc brake around, and nowadays a lot more bikes come with them as standard equipment.

With more and more of these brakes hitting the pavement, I thought of sharing my experience of maintaining them for those new to one of TRP’s star products. One of the bigger jobs is brake pad replacement.

Fortunately for us, many of TRP’s disc brake calipers, Spyre included, use readily available Shimano brake pads. These are the rectangular “B01S” shape, with a perforated panhandle at the center, and were used on Shimano’s Deore M515 mechanical disc brakes. (Locally, they seem to be called “non-series” brake pads for some strange reason.)

Shimano B01S resin brake pads, with return spring and retaining pin. These will slot into a TRP Spyre caliper just fine.

“B01S” itself, in Shimano parlance, refers to a specific pad with organic resin friction material. While it’s a good set of pads, resin tends to wear quickly in the cut-and-thrust action that characterizes bike riding in Metro Manila. Rain and wet conditions don’t do them any favors either. Lastly, they’re a minor step back from the semi-metallic brake pads TRP give you as stock equipment in each Spyre caliper.

That said, there are semi-metallic and metallic options that come in the Shimano B01S shape if you desire a longer-lasting, more powerful brake pad. The ones I’ve used have come from Ashima and Jagwire.

Anyway, to replace brake pads on a Spyre, you will need:

• 3 mm Hex key/Allen wrench
• New brake pads

The first thing to do is to remove the wheel. One of the few downsides to the Spyre’s design is it doesn’t allow for pad changes with the wheel still in the dropouts.

Next, take the 3 mm hex key and pry off the little cotter pin on the end of the pad retention bolt. Take care not to lose this!

Use the same tool to loosen the pad retention bolt, then slide it right out.

Once the pad retention bolt is out, only the return spring between the pads is keeping them in place. You can now pinch the old pair of pads and pull them out of the caliper body.

Exploded view of everything that goes out in a brake pad replacement procedure. Note the tiny cotter pin and the return spring, which is normally sandwiched in between pads.

Now is an excellent time to inspect the pads for wear. A new pair of Shimano B01S pads comes with 2 mm worth of friction material. Once your pads wear down to 1 mm, you should start considering replacement.

Friction material on a pair of fresh Shimano B01S pads.

These TRP pads are worn down to 1 mm of material. Replacing them now would be a good idea.

Shimano resin B01S pads on the left, TRP’s stock semi-metallic pads on the right. The circle on the TRP pad’s backing plate is an impression made by the Spyre’s piston.

Replacing pads is just the reverse of removal. Before doing so, wind out the pad adjusters on both ends of the actuation arm by turning them counterclockwise with the 3 mm hex key.

Sandwich the return spring between the new pads, making sure to avoid touching the friction material itself. Now it’s just a matter of sliding the pads into the caliper and threading the pad retention bolt through everything. Don’t forget the tiny cotter pin at the end.

Inserting new pads.

The pad retention bolt should thread through the holes in the caliper body, both pads, and the retention spring. Pop the cotter pin back on once it’s tightened down.

THINGS TO WATCH OUT FOR

• When pulling the brake lever, there should not be any loud clicking or snapping noise. In my experience, that’s a telltale sign that at least one brake pad has worn away all its friction material, and needs to be replaced immediately. That loud noise seems like the return spring slapping against the brake pad’s backing plate.
• My audax buddy Sean shared a story with me about an odd rattling from the front of his new Giant Defy Advanced 2 endurance road bike, which has Spyre calipers as well. The rattle would come each time he hit a bad patch of road. The phenomenon went on, misdiagnosed for a few times as a loose headset or noisy internal cables, until he noticed there was zero rattle when the front brake was engaged. He traced the root cause to a weak or malformed return spring. Once he spread out the return spring, and reinstalled the pads, the rattle disappeared for good.
• Lance left a pretty helpful comment: The other day I was adjusting the 3 mm screw, and found that if I used a 0.2mm feeler gauge between the pads and the rotor on both sides, I could get a pretty accurate clearance, the same on both sides of the rotor. I didn’t need to guess if I had turned one screw more or less than the other, and got good results on brake lever pull. Probably could use a business card [as substitute]. I adjusted one side at a time. It’s not the folded business card trick for centering the caliper, it’s when you’ve already locked down the caliper and adjusting each pad.