Disc Brake Pads: What You Need to Know

Seemingly simple, disc brake pads can have a big effect on your bike’s performance. Metallic and organic pads each provide their own unique benefits and drawbacks suited to certain conditions and riding styles. Choosing the correct disc brake pad compound for your needs will go a long way towards maximizing your fun on the bike.

What’s in a Name?

Each compound, metallic or organic, consists of a friction component—which provides braking force—and a binding component. Metallic pads include mostly metals like iron, bronze, copper, and steel, but can also contain graphite and ceramic. Organic compounds include glass, rubber, mineral fibers and even Kevlar. Friction and binding components are mixed, compressed into shape, and placed on a backing plate before being heated in an oven where the binding components melt, fixing the pad to the plate and holding the friction components together.

Screen shot 2014-09-17 at 10.33.04 AMCompound Characteristics

Organic/semi-metallic/resin pads are softer and tend to be quieter. They offer more initial bite, but fade faster than metallic pads on longer descents. Metallic pads last longer (especially in muddy conditions), handle heat better, and resist fade better under heavier braking loads.

Bed In Process

When new, rotors and pads have imperfect surfaces that appear rough on the microscopic level. By bedding in the pads and rotors together correctly, a thin layer of brake pad material is slowly and evenly transferred to the rotor, filling in the rough surface of the rotor and wearing the pad face until the two surfaces are smooth. This thin layer of brake pad material on the rotor gives the pad something to grab onto, and the smooth interface creates more surface area for maximum friction.

Bedding in brakes and rotors is a simple but crucial process. First, pads and rotors must be clean; be careful not to touch the pad surface with your fingers when unpacking and installing them. Clean the rotors with a non-residual cleaner like isopropyl alcohol. Once the rotor is clean, do not touch the braking surfaces. After the pads are installed, pedal up to speed and then gently grab the levers, slowly and smoothly applying pressure until you almost come to a stop. Do not stop quickly, let the brakes drag you down to a slow walking speed. You want to heat the pads enough to lay down the transfer layer of pad material evenly across the rotor surface, and that’s all. Complete this slow stop process twenty times, and you’re good to go. Braking too hard and thus generating too much heat will build up an uneven transfer layer, resulting in noisy brakes, wobbly-feeling rotors and underpowered braking. Coming to a complete stop will also lead to uneven pad material transfer, so this should be avoided as well.

Where Does this Leave You?

Pad choice is influenced by several factors, including riding discipline, terrain, and brake manufacturer. Metallic pads and their harder compound will last longer than the softer organic compound, but that doesn’t mean you should use metallic pads unquestioningly.

Your first consideration should be about your braking power requirements. Downhillers, bigger riders, and those who ride steep and fast terrain need the improved stopping power provided by metallic pads. More consistent throughout the lever stroke, and better at dissipating heat so the rotor temperature doesn’t get so high as to lose effectiveness, metallic pads are much better at delivering consistent power throughout a descent.

The one downside of metallic pads is they have a tendency to glaze over after cooling off following a long descent. However, a little glaze won’t destroy your pads. After a couple of good stops the vents in the brake rotor will scrape this glazed layer off of the surface of the pad thereby restoring normal braking performance.

If you ride less critical terrain, or even critical terrain without long downhill sections, organic pads provide some beneficial characteristics. Lighter weight riders, or riders who are light on the brakes, might prefer organic pads and their more pronounced initial bite than metallic pads. However, organic pads fade more than metallic pads, making them not well suited for long, high-speed descents where repeated hard braking creates extreme heat build-up.

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The Birzman Tools Disc Brake Piston Press

Organic pads should also be avoided in muddy or otherwise wet conditions. The softer compound of organic pads cannot stand up to the onslaught of grit, and will wear away quickly. Organic pads have been known to completely dissolve in one day of riding in very adverse weather. In wet conditions, metallic pads are a must.

Buying Brake Pads

Deciding between metallic and organic pads is only the first step. Most brake calipers are compatible with a specifically shaped pad, and will not accept others. When purchasing new pads, be sure to note the model of your brakes, and not just the manufacturer.

Aftermarket pads are common, with specialty brands like Swissstop offering high quality products that rival or exceed the performance of OE brands.

Installing disc brake pads is easy; simply remove the wheel, pull the pads out of the caliper—which may or may not require removing a fixing bolt—and reset the caliper pistons, as shown in this Art’s Cyclery Learning Center video. Drop the new pads in the same side you removed them from, and reinstall the fixing bolt if necessary. Again, be careful not to touch the surface of either side of the rotor or the pad’s braking surface.

Life, and mountain biking, is in the details. Paying attention to the little things, like disc brake pads, will go a long way towards enhancing your riding experience and maximizing your fun factor.