Originally Posted by merlinextraligh

But all that weight results in momentum that has to be slowed. So the added weight doesn't make the car stop faster. (if it did a Semi would outbreak a Porsche).


The reason the car will stop faster is the size of the contact patch as a function of weight.


Bike has about 2" of contact patch and a combined weight of say 200lbs.

Economy car example has a contact patch of at least 120". Assuming a total weight of 3,000lbs, the car has 15 times the weight, but 60 times the braking surface.

Thus with a similar tire compound and therefore an equal coefficient of friction per inch of contact patch, the car is going to stop faster.