Different brake pad compounds can make a huge difference to braking performance with each having their own advantages and disadvantages. The brake pad compound we choose ultimately comes down to personal preference (when you take into account the conditions in which you’re riding) but if you’re new to brake pad compounds the choice open to you can be confusing.
There are basically three different types of brake pad compound available (with several names used interchangeably for each):
– Sintered pads / Metal pads / Metallic pads
– Organic pads / Resin pads
– Semi-sintered pads / Semi-metal pads / Semi-metallic pads.
You’ll struggle to tell the different compounds apart just by looking so it’s pretty much essential to check the packaging / product description to know what you’re buying.
Sintering involves fusing metallic particles together under heat and pressure and, in the case of brakes, other elements are added to enhance the frictional properties. The steel backing plates of the brake pads are copper coated and the backing plate and back of the pad are shaped to interlock. When these parts are passed through a furnace, the copper coating under the pad melts fusing the pad and plate together. There are also aluminium back plates available which reduce weight for the weight weenies out there.
The advantage of these (nearly) all metal brake pads, is they provide a stable coefficient of friction from hot to cold ie there performance stays stable. This means they are well suited to conditions where brake use is heavy and, as a result, there are extremes of heat stress on the pads eg downhill riding or Alpine descents. As sintered pads conduct heat back through the calliper (rather than heating the disc) braking power doesn’t fade in the same way as it does wth an organic pad. If you are running small rotors there may be some benefit to using sintered pads as a result. In addition to this, their hardness means they will last longer and perform well in just about any weather condition, including rain, snow, mud and dusty conditions.
On the flip side they do have their drawbacks. The harder pad material means they don’t ‘grab’ as well as organics and put more wear and tear on (the more expensive) rotors. For this reason if your bike’s rotors are not made to be used with sintered pads, you should absolutely not use them. Sintered pads also tend to be ‘noisier’ than organic pads due to vibrations that can occur between the hard pad and disc rotor when the brakes are applied (otherwise known as ‘brake squeal’). Finally, because the materials and the processes used to make them are more expensive, you can expect to pay more for sintered pads.
They last longer than organic pads.
They give stable braking performance across a wide range of conditions and use.
They don’t ‘glaze over’.
They are less prone to ‘fade’ during sustained high speed eg downhill and Alpine descents.
They perform well in wet and muddy conditions.
They have a longer break-in period.
Higher calliper temperatures can cause mineral oil systems to fade on very long sustained descents.
They lack initial bite feel.
They can be noisy.
Organic pads are made up of a matrix of organic fibres and fillers that are bonded together with resin. In some cases high tech fibres like Kevlar and carbon may be used to increase pad durability.
The ‘softer’ makeup of these pads means a lower ‘bite’ point and hence more control at lower speeds and a more varied and progressive feel when you apply the brakes. The softer materials that are used to make organic brake pads mean they produce very little wear on rotors and are ‘quieter’ than sintered pads. They are generally cheaper than sintered pads because the materials and manufacturing processes used are less expensive.
On the flip side, organic pads are softer and so wear out quicker meaning more replacements and brake bleeds. Another downside is that organic pads heat up to their maximum operating temperature quickly during sustained or heavy use and lose their coefficient of friction. If ridden in wet or muddy conditions, organic brake pads will not be able to perform to their full potential and can even build up a ‘glaze’ that interferes with subsequent braking efficiency, even in dry conditions (though this is relatively easily rectified by rubbing them with sandpaper).
They have a shorter break-in period.
They are pretty much noise free.
They have more initial bite and better modulation.
Heat from braking energy isn’t conducted away but is retained in the rotor therefore they’re theoretically better for mineral oil systems.
The pads wear out much quicker than sintered pads (especially in wet/muddy conditions).
They are prone to power fade during sustained high speed braking eg downhill or Alpine descents.
The pads can ‘glaze’.
Semi-Sintered Brake Pads
Semi-sintered pads offer a ‘best of both worlds’ approach to braking. They combine the longer life of sintered pads with the progressive feel and lack of rotor wear of organic. The construction of the semi-sintered pads is generally around 30% copper by weight within an organic matrix. These pads fall in the middle ground for durability and performance and are a good compromise if you are struggling to decide between sintered and organic.
Most of the best bits of sintered and organic compounds.
Balanced performance offering a mix of bite feel and modulation with less
Can glaze over.
Not all semi-sintered compounds are the same ie. different brands will have different metallic to organic mix ratios.
Usually a bit more expensive.
Overall, unless you’re at an obvious extreme of mountain biking ie if you’re riding long Alpine style descents you’re likely to want sintered pads or if you’re riding street trials you’ll want organic, the majority of mountain bikers are likely to want an easy life and, as such, will probably go for semi-sintered pads or even plain organic (the majority of weekend riders are unlikely to place enough strain on the organic pads to notice their durability limitations).
If you are wanting to experiment, another option you have is to run a sintered pad in the rear brake and an organic pad at the front. The reasoning behind this is that, if considering brake force distribution, roughly 70% of your braking is done by the front brake with roughly 30% of braking being done by the back brake (this is dependent on technique). As there is less need for braking power modulation and generally more muck and dirt thrown at the rear brake it makes some sense to run a sintered pad there while an organic pad in the front brake will optimise power and handling.
If you’re going to take the time to practice, practice like the elite