What stops faster "Car VS bike" - debate

[twinn]

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RE: after market brakes and stopping distance.

I think there would be a difference but it would be very marginal.

Aftermarket brakes are not designed for the average street driver. When someone adds more horsepower, top end speed, more weight (as in a heavier engine), bigger tires/rims (more weight again). They will need to upgrade their brakes to offset the various factors.

Where the difference in aftermarket brakes will be seen is in repeated hard use over a short period of time, ie like a track day (regardless of car or bike) or in applications that the machine was not designed for (ie. stunting a bike)

In tests run by people, even professionals, the smallest difference will effect the outcome. A split second delay in braking, braking with the smallest amount of difference in pressure etc.. all factors that are impossible to duplicate time over time.

 

[JohnnyP636]

In tests run by people, even professionals, the smallest difference will effect the outcome. A split second delay in braking, braking with the smallest amount of difference in pressure etc.. all factors that are impossible to duplicate time over time.

The more I think about it the more variables i think of

Has the rider/driver had enough seat time in the vehicle to get familiar with the brakes to be able to use them to their potential

If its a new vehicle have the brakes been used enough to have been broken in properly and attain the best performance

Are the runs both being run on cold brakes or hot

 

[V-Tom]

I voted car, but after re-reading the question I might change my answer.

The reason, I thought we were talking best car and best bike. I didn't realize we were talking average sport bike and average car.

There are a lot of variables here that can make the answer go either way depending on how you setup the question.

I think the best cars can outbrake the best bikes for the one reason mentioned earlier: weight shift. The high center of gravity on a bike relative to the wheelbase works against it and ultimately limits the ability of the brakes to be used to their full potential. I think that on a good sports car (say a Porsche 911) the rearward weight bias and very low center of gravity works in its favour.

But I think the average sport bike is far superior to the average car because of sticky tires and decent brakes vs. cheapy brakes and relatively hard, all season tires. The average car will lockup the tires (or force ABS to engage) long before a sport bike with the usual sticky tires

If we were doing average bike (in North America), I think the results could be skewed to lower performance as there are so many cruisers out there which simply don't have braking ability anything close to that of a sport bike. The type of tires plus (in general) underperforming brakes means that an average car might outperform it.

..Tom

 

[mike.from.canmore]

The more I think about it the more variables i think of

Has the rider/driver had enough seat time in the vehicle to get familiar with the brakes to be able to use them to their potential

If its a new vehicle have the brakes been used enough to have been broken in properly and attain the best performance

Are the runs both being run on cold brakes or hot

Eliminate those variables.

Seat time/ familiarity with the brakes = equal in both cases
have the brakes been broken in properly = equal in both cases
cold or hot brakes = equal in both cases.


All those variables should can be dealt with. just make them equal in both cases. We've already specified the brakes being cold, it's a one stop test.
Broken in properly, sure, both car and bike are working as they should & being driving/ridden by drivers/riders with nearly equal skill level.

 

[JohnnyP636]

Eliminate those variables.

Seat time/ familiarity with the brakes = equal in both cases
have the brakes been broken in properly = equal in both cases
cold or hot brakes = equal in both cases.


All those variables should can be dealt with. just make them equal in both cases. We've already specified the brakes being cold, it's a one stop test.
Broken in properly, sure, both car and bike are working as they should & being driving/ridden by drivers/riders with nearly equal skill level.

Maybe in a real study, but not those do it yourself youtube vids someone posted....I dont buy those

 

[SunnY S]

How can you say this? The link proves EVERYTHING.

Ok, so we have German sportsbike, along with the Japanese. Its still a modern sportsbike compared to a typical road car.

http://www.motorcyclenews.com/MCN/News/newsresults/First-rides--tests/2009/December/dec2309-bmw-k1300s-wins-abs-test/

Period.




Look at the original post.




"What do you people (not meant in a racist way), think stops faster?


car stops faster cause it has 4 wheels" is also a stupid post. try to add some facts & figures & supporting documentation if available. - and at a very minimum, include why you have the view that you do.

EDIT - lets compare modern day sportbikes (Japanese) to modern day common cars - Civic, Mazda 3, Accord, - that kind of thing.
EDIT #2 - For those of you who chose "with ABS".. this poll is for braking in a straight line, on good pavement, with no obstacles. - I thought that by omiting that fact, that the default assumption would be straight "

This test proves nothing.

Why they compare a run of the mill appliance type car to a virtually top of the heap bike is beyond me.

While it is always apples to oranges a better comparison to the Civic is to run it against something like a Versys or other similar "standard" appliance type bike or to run the K13 against something like a Z06.

 

[V-Tom]

How can you say this? The link proves EVERYTHING.
...

Without seeing the raw numbers, and taking note that the conditions were "wet and damp" it actually proves little, except to say that in those conditions one bike beat one car. I implies that the car (a rather average one) beat all the other bikes.

But the condtions were wet and damp, which really suggests this is more of a test of tires and ABS than anything else.

..Tom

 

[Streetfighter]

In all seriousness, this is something I want to submit to mythbusters.

 

[Declan Gunn]

somebody submit this to mythbusters!

 

[Griffin]

somebody submit this to mythbusters!

At the end of the day, who cares?

It's more important to me that I stop before I hit the truck. Regardless of whether I'm driving a car or a bike.

This is like one of those stupid television shows about what is a more better fighter, a ninja or a gladiator. Who the hell cares and how could you actually assess it anyway?

 

[wild2crazy]

I think you might be somewhat surprised just how fast a transport truck can stop. The air brakes are not nearly as responsive as hydraulic brakes, making threshold braking nearly impossible. I'm not aware of any Air brake ABS technology!

You have NO data regarding this - neither do I... so why are we talking about transports?

then you never seen air brake truck then because 90% of all new heavy duty trucks must have abs and sensor systems.

i test air brake systems all day long

air brake responds 0.25- 0.30 of a second. goverment won't let a truck out of the factory with air brakes below 0.45 of a second


This is regarding apply/release times which is what i believe your asking for which is faster hydraulic or air brake.
Trucks moving with weight on them stopping distances is a totaly different story. A heavy duty trucks have enough pressure to lock the wheels that why you see most of the long skid marks all over the 401 and major highways.

i seen most apply time as short as 0.19 of a second now finding brake times for the hydraulics will be a little tougher, problem with this is that hydrualic systems only go up to medium-duty trucks. You would also need air brakes to operate the trailer

 

[Streetfighter]

At the end of the day, who cares?

It's more important to me that I stop before I hit the truck. Regardless of whether I'm driving a car or a bike.

This is like one of those stupid television shows about what is a more better fighter, a ninja or a gladiator. Who the hell cares and how could you actually assess it anyway?

Your parents were probably the kind who sat you in front of a television to stifle any form of creative thought eh? **** man, curiosity is not a bad thing, hell it encourages technological advancement for goodness sake.

 

[wild2crazy]

Then hopefully the truck not going through you first lol

 

[mike.from.canmore]

then you never seen air brake truck then because 90% of all new heavy duty trucks must have abs and sensor systems.

i test air brake systems all day long

air brake responds 0.25- 0.30 of a second. goverment won't let a truck out of the factory with air brakes below 0.45 of a second


This is regarding apply/release times which is what i believe your asking for which is faster hydraulic or air brake.
Trucks moving with weight on them stopping distances is a totaly different story. A heavy duty trucks have enough pressure to lock the wheels that why you see most of the long skid marks all over the 401 and major highways.

i seen most apply time as short as 0.19 of a second now finding brake times for the hydraulics will be a little tougher, problem with this is that hydrualic systems only go up to medium-duty trucks. You would also need air brakes to operate the trailer

I'm not sure what you are saying? I was unaware of any Air brake ABS applications. If they exist. great. But this is so far out of scope of this debate.


0.19 seconds of delay between touching brake pedal and brakes applying is HUGE compared to any hydraulic system. - totally our of scope.

 

[mike.from.canmore]

Without seeing the raw numbers, and taking note that the conditions were "wet and damp" it actually proves little, except to say that in those conditions one bike beat one car. I implies that the car (a rather average one) beat all the other bikes.

But the condtions were wet and damp, which really suggests this is more of a test of tires and ABS than anything else.

..Tom

Exaclty... I fail to see where SunnY S is coming from.

it would seem, according to that article, that
all modern day sport bikes took longer to stop than that modern day common car - under those wet/damp conditions, and the exception was one single super advanced german $17,000 machine

 

[mike.from.canmore]

**** man, curiosity is not a bad thing, hell it encourages technological advancement for goodness sake.

yup
+1

 

[JohnnyP636]

What do you guys think about this? Since it seems the biggest factor in stopping distance is tire traction and threshold braking without locking up the wheels, do you guys think if we put wider front tries on our bike with more contact patch..Could the bike stop in a shorter distance? Or even deflate your regular front tire, so it sits flatter and has more contact patch....

 

[mma01]

do you guys think if we put wider front tries on our bike with more contact patch..Could the bike stop in a shorter distance?

On a car, wider/sticker tires will help shorten braking distances, but I dont think that its going to help much on a bike b/c the limiting factor is still going to be weight transfer.

 

[mike.from.canmore]

What do you guys think about this? Since it seems the biggest factor in stopping distance is tire traction and threshold braking without locking up the wheels, do you guys think if we put wider front tries on our bike with more contact patch..Could the bike stop in a shorter distance? Or even deflate your regular front tire, so it sits flatter and has more contact patch....

nope...


say your bike is 100 lbs (ease of use number).
and your current contact patch is 1 sq inch (ease of use number)

you would have a contact pressure of 100 PSI, and a contact force of 100 lbs


If you double the contact patch to 2 sq in... the contact force doesn't change, but the contact pressure drops to 50 psi.

Simply distributing the load doesn't help traction/friction.

What I'm trying to say is... the coefficient of friction is independent of contact patch.

http://en.wikipedia.org/wiki/Friction



Debating the tire width VS traction issue has already been done here - http://www.physicsforums.com/archive/index.php/t-330790.html

xxChrisxx knows what he's talking about on that forum.

from the above link talking about tire widths

As example I can think of is formula student cars, they used to use 8inch tires but couldnt get them up to temperature. They switched to 6.5inch and got more grip because they can get them up to temp.

 

[mike.from.canmore]

On a car, wider/sticker tires will help shorten braking distances, but I dont think that its going to help much on a bike b/c the limiting factor is still going to be weight transfer.

Stickier - yes. weight transfer/flip over is still the problem
But wider isn't necessarily better. there is of course an optimum width.

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