Bike VS Car - Calliper Clamping Power

[trkdayz]

A bit of a random one,

Does anyone know which brake calliper produces more clamping pressure/force is it on a Super Bike or on a Super Car?
I am having a bit of a debate with one of my mates and he is adamant that a bike’s calliper will produce more clamping force/pressure because a bike brakes a lot quicker, however I would have though that a car would need a lot more clamping force because it is a lot heavier.

Cheers

[busta]

You're right, he's wrong.

Firstly, cars brake faster than motorbikes. More than that, it takes a very skilled bike rider to brake at the limits of his bike.

The fact that motorbike brakes are un-servoed and can be operated with just a couple of fingers should be proof enough.

Also the discs are thinner as they generate much less heat which is a factor of the power applied.

And lastly, slowing 1,500kg from 100mph-0 takes a lot more power than 200kg.

Edited by busta on Wednesday 16th June 22:52

[panic458]

car.
the force in both cases is provided by the pilot. in a super car this is applied by your leg (big muscle) boosted by a servo. on a bike it is provided by your fingers.
if you really mean breaking efficiency then this is an almost infinitely variable combination of factors from pad contact area to pad and disc materials (coefficient of friction) however, the answer remains ....car.

[Colin 1985]

trkdayz said:

A bit of a random one,

Does anyone know which brake calliper produces more clamping pressure/force is it on a Super Bike or on a Super Car?
I am having a bit of a debate with one of my mates and he is adamant that a bike’s calliper will produce more clamping force/pressure because a bike brakes a lot quicker, however I would have though that a car would need a lot more clamping force because it is a lot heavier.

Cheers

Your sure about that?

[dan19evans]

i'd say a car. the brake discs on cars are alot bigger than the ones on bikes, not to mention the 6 or even 8 pot calipers. dont think bikes have a servo either (im no bike expert)

[anonymous-user]

Car.

2 x 4 piston monoblock on a lardy superbike can lock the front at any speed but it has very limited grip and mass compared to a car.

[Conian]

Colin 1985 said:

trkdayz said:

A bit of a random one,

Does anyone know which brake calliper produces more clamping pressure/force is it on a Super Bike or on a Super Car?
I am having a bit of a debate with one of my mates and he is adamant that a bike’s calliper will produce more clamping force/pressure because a bike brakes a lot quicker, however I would have though that a car would need a lot more clamping force because it is a lot heavier.

Cheers

Your sure about that?

it just feels that way when your balls are pressing against a fuel tank and the brakes are causing you to squish them

[busta]

Just pinched this off a bike forum, quoted from a bike magazine test:

- Subaru WRX 60-0mph 39.6m
- Suzuki GSX-R1000 60-0mph 42.2m
- Suzuki GS500E 60-0mph 47.7m

[Colin 1985]

Can't find the other years results right now (but do have them burred deep in the draw), but anyway generally a car (even an ordinary car) will out brake a bike.

Given that a car might be 7 or 8 times the weight of a bike I would expect their calipers to be able to exert more force in order to bring this increased weight to a stop in a shorter distance. As for breaking pressure ie. the pressure per unit area, I don't know how large the pads on a bike are?

[the_lone_wolf]

Colin 1985 said:

I don't know how large the pads on a bike are?

They're usually the rough shape of a curved rectangle, I'd hazard a guess at the typical size being around 20x80mm, two per calliper so four in total on the front of a sportsbike

[Colin 1985]

the_lone_wolf said:

Colin 1985 said:

I don't know how large the pads on a bike are?

They're usually the rough shape of a curved rectangle, I'd hazard a guess at the typical size being around 20x80mm, two per calliper so four in total on the front of a sportsbike

So lets say 1600mm^2 per pad time 4 = 6400mm^2 at the front for a bike.

Focus ST170 pad:-

lets say size of friction area = 100x65mm=6500mm^2 x 4 = 26000mm^2

bike & rider 250kg 90% weight on front brake ~ 23mm^2 area/ kg of bike
car and driver 1300kg, 90% weight on front brake ~ 18mm^2 area/ kg of car
So in this case the car has more weight for the same braking area (which needs more pressure), but on a supercar with much larger brakes the pressure is reduced.
So not too far different in terms of pressure per unit area on the actual breaks pads (remembering the pads on a car are larger and hence exert more force, but may have a similar force per unit or area (pressure).

So using very rough figures (since I couldn't find real ones on the internet), and assuming similar friction properties, I would expect;
-Clamping force (ie. newtons) to be much greater for a car.
-Contact pressure (ie. newtons/mm^2) of the pads to be slightly higher for a car (in the above case).
-Fluid pressure (ie. newtons/mm^2) to be higher in a car for the reasons stated in other posts above.