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Old 12-01-2005, 05:24 PM
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Default Re: The Final Word on front disc brakes

That is only partially true...

Brakes work based on friction. The frictional force between two sliding objects is based ONLY on TWO factors:

1. The Normal Force, or in Layman's terms, the force holding the two objects together. (In our case this is the clamping force exerted by the caliper onto the pads and rotor)

2. The coefficient of friction, which is a property of the materials that the sliding objects are made of. (In our case, this has to do with the materials used for the rotor and the brake pads). When you swap to "high grip" brake pads you are changing this property.

You can look up this equation in any basic Physics textbook. Note that the AREA of the contact (for example, the size of the pads) does not enter into this equation at all. I know it is counter-intuitive, but it is true.

Now then, larger brake pads are going to be more DURABLE than smaller ones, becasue the energy lost to friction is spread out over a larger area. So yes, in a way larger brake pads and larger numbers of pistons are better in some regards: durability and resistance to heat-based fade and damage.

But for RAW BRAKING POWER ONLY, area is king.

Of course, all of the above assumes that the caliper is stiff enough to actually apply the force to the pads. If you have a caliper with giant pistons but it is too flexible to properly clamp the pads then you will never realize the benefits of all that area. As I noted at the end of my original post, the stiffness of the calipers might affect the results. I have no way to measure the stiffness of the various calipers discussed, so I can't really comment on that. However, it is something to think about.
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