Wednesday, November 23, 2022

Shimano Hydraulic Disc Brake Pads: Resin vs Metal, With and Without Cooling Fins

Here is a detailed blog post comparing the different brake pads made by Shimano, for their hydraulic disc brakes. With many model numbers used for the different brake pads, it is confusing for almost everyone.

However, after studying and comparing many different brake pads, I think I have got it figured out. Each brake pad has a specific model number, such as L03A, or K05Ti, etc.

Breaking down this model number into the different parts, using L03A Resin as an example.

L: Shape of brake pad, to match different brake calipers.
03: Version of brake pad. Different revisions are cross-compatible if the other parameters are the same.
A: Aluminium backing material.
Resin: Resin material used for the pad, to reduce noise.

First letter denotes the shape of brake pad. L is the finned brake pad used for road brake calipers.
Other letters that I have seen are K (similar shape and compatibility as L, but without fins) and H (4 piston brake pads). There is also the J and G type for other brake pads, just to name a few.

This is followed by a number, usually 02, 03, 04, 05 and so on. It is just the revision number of this brake pad design. For example, L02A was recently replaced by L03A, which has a more durable resin pad material. Different revisions are compatible as the pad shape is unchanged.

After the number, the letter refers to the backing material. The backing is the plate that the brake pad is attached to. This can be made with aluminium, steel or titanium.
A: Aluminium
S: Steel
Ti: Titanium
C: Combined

Final part of the model number refers to the pad material, whether it is made of resin or metal.

With different backing materials, different pad materials, and different shapes, it gives rise to many different combinations and thus many different options. In fact, I think there are too many variations which makes it very confusing.

Here are 5 different brake pads that I have, to match different brake calipers.

Metal brake pads shown here.
K04Ti Metal: K shape, version 04, titanium backing, metal pads.
L04C Metal: L shape with fins, version 04, combined backing (aluminium + steel), metal pads.

Resin brake pads shown here.
K05Ti-RX: K shape, version 05, titanium backing, resin pads.
L03A Resin: L shape with fins, version 03, aluminium backing, resin pads.
H03A Resin: H shape (4 piston), version 03, aluminium backing, resin pads.

With all these examples, the model number code is now clear. Now I have learnt how to identify each type of brake pad.

Let's take a closer look at the difference between resin and metal brake pads. For the pros and cons of each type, you can Google for the answers.

Metal brake pad on the left, resin on the right. The metal pads have much more metal content inside as seen from the reflectiveness. This also adds to the weight.

The metal pad on the right has a separate steel backing, which is riveted to the aluminium backing with cooling fins. I am not sure why it is made this way, instead of the bonded construction like the resin pad.

A pair of resin brake pads with aluminium cooling fins weigh 17 grams. This is the most common brake pad used on Shimano road hydraulic brake calipers.

A pair of metal brake pads with aluminium cooling fins weigh more, at 26 grams. Useful for more braking power if you want to go off-road on gravel bikes.

Resin brake pads without cooling fins, with titanium backing. 12 grams for the pair. Lightest brake pad out of all the variations.

Resin brake pads without cooling fins, with steel backing. Weighs 5 grams more than the titanium backing version.

Metal brake pads without cooling fins, with titanium backing. 15 grams for the pair.

H03A Resin, used for some 4 piston MTB brakes, such as the Deore XT brakes used on the Bike Friday Haul-A-Day cargo bike.

Summary of actual weight for different brake pad configurations

2 Piston Resin Pad
With aluminium backing and fins: 17 grams
With steel backing, no fins: 17 grams
With titanium backing, no fins: 12 grams

2 Piston Metallic Pad
With aluminium+steel backing and fins: 26 grams
With steel backing, no fins: 22 grams (estimated)
With titanium backing, no fins: 15 grams

4 Piston Resin Pad
With aluminium backing and fins: 25 grams

In summary, if you want to reduce weight, use resin brake pads as they are lighter than metallic brake pads. Using the titanium backing with no cooling fins will also save some weight over the aluminium backing with fins. That said, the weight difference is only 5 grams (17 vs 12 grams) per brake, giving a total savings of only 10 grams per bike.

With such a small difference, it is more important to choose the correct brake pad, depending on your needs or preference, rather than weight.

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