Pad area is the next consideration. When the pistons clamp the rotor, the same force is transmitted to the rotor regardless of pad area...it is just spread over a greater area (to change the force, you need to change the piston diameter, NOT the pad area). Consequently, provided the pad friction coefficient is the same, different size pads will produce similar braking effort for the same pedal force. What changes is pad heating and wear rate. Small pads concentrate heat more and hence get hotter, and will wear faster. The temperature change also affects their coefficient of friction (depending on the compound, it usually goes up as the pads heat up, and at some temperature they go off, lose their C of F until they overheat, disintegrate and fail.
Jamo, I need some help to understand this. My manbrain tells me that braking force will be determined by the amount of friction created at the disc surface. I would suggest - and I'm not an engineer or a physisist - that size of pad would be a significant contributor to the friction equation. Obviously keeping pressure and pad material constant then pad area would make a massive difference. I take your point that if you can increase pressure it will improve braking force, but I can't get my head around that different pad size will not affect braking force.
A little experiment that I did as I was trying to work this one out was:
I placed the pad of my middle finger lightly on my desk and dragged it towards me. I then placed my whole hand on the desk, with as close to the same force (arm effort) and dragged that towards me. Obviously this is a huge increase in 'pad' size, but the friction increase (resistance to drag) was substantial.
Please help me to understand. I promise you that I am not taking the pi$$, I really do want to understand.
To the rest of you - stop dragging your hands across your desks and get on with your work!