Can a motorbike out brake a car?

[*caution*]

Henry is correct - when you do the sums to calculate decelerative force mass cancels out. You are left with gravity and friction. Since gravity is the same for both the defining factor is friction. If you assume no wheel lock up then it all comes down to braking efficiency.

Mikkel is also correct because mass comes back into play when you consider energy. Ie ability of the brakes to convert kinetic energy into heat.

Bikes have fewer brakes but less energy to dissipate. Cars have more brakes but more energy. The winner all depends on what you consider average. I wouldn't like to pick it.

And Friction between the tires and the road is dependant on mass, (along with a few other things), in theory for the same mass, and rubber and road total friction is the same no matter the contact patch, (seems odd but if you try the calculations its true, because as contact area reduces for the same mass average pressure on that patch increases, friction is a function of pressure) but then the coefficient of friction for the rubber is not constant, it changes with temperature, so the calculations start to become very complex, the straight answer is yes a motorbike can outbrake a car, but a car can also outbrake a motorbike, a better questions is can X motorbike outbreak Y car.....

Experiments are always fun though!!

[moT]

Y^= Bo + By X which means that the total variation / total variation - unexplained variation/ total variation = explained variation /total variaation

which gives you the R2 regression

[sAsLEX]

Y^= Bo + By X which means that the total variation / total variation - unexplained variation/ total variation = explained variation /total variaation

which gives you the R2 regression

Which explains why Rossi et al take their left foot off when braking....... duh!

[Ixion]

But it doesn't work with a shaft drive, eh.

[jrandom]

I only brake with the bottom half of my wheels.

[Ixion]

And only accelerate with the top half ?

(Actually, that is sort of true. But it doesn't work with a shaft drive, either)

[Deano]

A vehicles weight, or inertia, doesn't significantly alter is braking performance. The dominating factor is the friction between the road and the tyres. Cars have a bigger contact patch so can apply a greater stopping force to the road.
.

And trucks have a huge contact patch, but how far does it take them to stop ?

[avgas]

6 of 1 half a dozen of the other.
Both can out brake each other.
It all complete depends on the situation.
I have had a bike stop instantly and a car slide for 40m. And vice versa. Generally you should not drive and ride where you can not see your average stopping distance. Always look for an exit rather than expecting your vehicle to stop immediately.

[koba]

And trucks have a huge contact patch, but how far does it take them to stop ?

Good point,
Farken ages when fully laden. Thats why I don't understand the idea that weight, or inertia doesn't significantly effect overall braking performance - ever tried braking with a trailer-load of gravel?

[avgas]

Good point,
Farken ages when fully laden. Thats why I don't understand the idea that weight, or inertia doesn't significantly effect overall braking performance - ever tried braking with a trailer-load of gravel?

Its actually simpler than you think - take a big rock and move it (ARGGHHHHHHHHGHGHGHHHGHGHGH!!!!) so its moving at constant speed. now take a small rock and move it as the same speed (weeeeeeeeee!) now get them rolling at that speed and let them go. While the small rock travels a good distance the big rock rolls into and through the neighbors fence.

[koba]

Its actually simpler than you think - take a big rock and move it (ARGGHHHHHHHHGHGHGHHHGHGHGH!!!!) so its moving at constant speed. now take a small rock and move it as the same speed (weeeeeeeeee!) now get them rolling at that speed and let them go. While the small rock travels a good distance the big rock rolls into and through the neighbors fence.

Yeah I got that, that is the way my brain thinks but above are comments that somehow that aint the case.
Leafves me a bit confused, as usual.

I think I may try a few tests, I have always wanteed to know how the braking of my two cars compares, maybe I should chuck the bikes into the test too....

[Mike748]

Nah .......
(wait for the totally ill informed opinion) ....
it's the stability and lower COG in a car that makes the difference, as long as you load the cars front brakes up you can get better stopping cause it won't stoppie!!!

[Mikkel]

Nah .......
(wait for the totally ill informed opinion) ....
it's the stability and lower COG in a car that makes the difference, as long as you load the cars front brakes up you can get better stopping cause it won't stoppie!!!

Yes!

...given that your tyres have enough grip, your brakes are good enough and you have skills.

[koba]

right but mass of the vehicle MUST surely make a difference...

[Mike748]

Mass does make a difference, just like tyres and brakes.
The problem with trucks is, tyres are designed for high k's, suspension is designed to support heavy loads and vehicle chasis is designed for weight distribution, so getting the transfer of energy to the road is way harder than a car or bike.
With trucks primarily designed to haul at low cost you cannot expect progressive performace braking.

(I know this is a generalisation and I'm not including the big modern long haul rigs in this)

Have driven some HT vehicles where the harder you push the brake the faster you go.