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Braking Distance of Car versus Motorcycle

54K views 55 replies 27 participants last post by  Unkle Krusty 
#1 ·
I recently heard that a car can stop faster and therefore shorter than a bike. I went, "No Way". Then I got to thinking about it and with the advancement of brakes and a light weight car, maybe it's true. I know that wasn't the case many moons ago but maybe it's true now. Cars have got lighter and brakes better with ABS. Anyone have any facts or links that can prove whether or not a car can indeed stop quicker than a motorcycle. I'm really having trouble thinking it's possible if you stay with apples and apples as far as weight. What do you think?
 
#3 ·
I think that, physically, a motorcycle will always have a shorter stopping distance (far less weight with 2-3 braking systems). However, I believe that there is a fear in some riders to use the safe potential of the brakes and that could cause a motorcycle to have a longer stopping distance.
 
#5 ·
I think you got that exactly right. The bike should stop faster, but that doesn't mean the rider can take advantage of that edge.

I recall learning in safety class that swerving usually beats braking, if you have the room, skill, and Zen to pull it off. I'm not sure if the bike beats the car in swerving, but I suspect it would if you have the skills.

It looks like you need about 50% more distance to stop the car. The difference is a bit greater at lower speeds:



http://auto-kult.com/motorcycle-vs-car-what-are-the-braking-distances.html
 
#6 ·
I saw that chart and the first thing I thought was the car was probably 75% heavier so that's not a fair comparison. I'd like to see something like a Goldwing and a Mini Cooper or similar. I think cars in general cannot stop faster but I'm wondering if there are some that can now given the advancement in brake technology.
 
#7 ·
The comparison is too general. Not every car can stop faster than every bike.

With a few exceptions above and below, sports cars typically stop around the same distances as sport bikes.

I will try to find the comparison chart I saw that listed actual makes and models later.
 
#8 ·
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As Murph has suggested, it can be a matter of weight. However, take extremes: say a locomotive vs. a bicycle in stopping quickly. No question. In this case though, you have two extremes where one has a million times more mass than the other. The amount of friction on the wheels of the train is tremendously more than the bike (ever put a penny on a track?), but in this case, the mass overrides that factor.

But typically it's the friction that matters as that's what primarily causes the reduction of speed. So if you were to compare a m.c. on ice to a cage on dry roadway, then the cage would stop quicker, but that's because you have modified the friction to an extreme disadvantage for the bike. Or if you were to compare overheated brakes on a car to a cool brake truck, the truck would stop shorter because of better efficiency of braking power even though it weighs more.

I guess my point is that you can manufacture situations where you can force any one vehicle to stop better than another. But if you put two vehicles side by side that are anywhere in the ballpark of equal weight and each is at its own peak of ability, then the lighter of the two will stop faster.

--
 
#9 ·
Cars can brake faster and safer than motorcycles in pretty much all situations - normal daily riding, Motogp versus F1, and average rider versus average driver however the numbers skew even further for the cars in wet, curves, or other poor traction situations like gravel or bumpy roads.

This is not even a debatable argument in my mind.





Can you brake faster than cars?
Good question. During our emergency braking exercises I always ask this question, and I get two answers, both wrong. One is "Certainly not; motorcycle tires have two small contact patches, car tires have four larger contact patches, so motorcycles have less traction." You can read my page on traction and contact patch area to see why contact patch area is irrelevant, so this answer is wrong. The other answer is "Certainly; you can accelerate faster than cars because you're lighter. You can decelerate faster than cars, because you're lighter." I subscribed to the second view until one of my students, Eli Baldwin, said that the physics in the two situations is entirely different. He's right. Motorcycles can accelerate faster than (most) cars because the ratio of power to weight is greater for motorcycles; there may be less horsepower but it's pushing a lot less weight. But for braking, the horsepower of the engine is irrelevant. To find out whether motorcycles brake better than cars we have to look deeper into the physics of braking.

The force on a vehicle during a stop is just the vehicle's mass times the (negative) acceleration, F = ma. That force has to be applied at the tires via their traction. The friction equation is F = μW (where W is the weight of the vehicle and μ is the Greek letter mu, the coefficient of friction — again see laws of friction for details). The weight of the vehicle is the mass m times the gravitational force g, so F = μmg. The maximum stopping force that can be applied is the maximum frictional force that the tires can sustain, so ma = μmg; and we can cancel the mass which appears on both sides to get the maximum deceleration possible:
a = μg

Now before we go further, let's note some assumptions. One is that the downwards force in the friction equation is actually the weight of the vehicle. Race cars use airfoils to develop a downward force to improve their traction, so their stopping distances would be better than an unassisted vehicle (at speeds allowing the airfoil to work). If street cars ever begin to use this technology then the conclusions would have to change to take that into account.

Another assumption is that the limiting factor in stopping is traction, rather than the ability of the brakes to dissipate the energy. This is true of cars and motorcycles at normal speeds, as their brakes can overwhelm the traction of the tires, causing a slide. But it isn't true of large trucks. Their additional mass provides additional traction, as shown in F = μmg, but the additional energy is more than the brakes can deal with, resulting in longer stopping distances. And a reader, Garrett Underwood, pointed out to me that as speeds increase, even cars and motorcycles may become limited by the ability of the brakes to deal with the energy (which increases as the square of the speed). If this point is reached then motorcycles may have an advantage in stopping distance, as motorcycles generally weigh a quarter or less of a car's weight, so the kinetic energy which must be converted to heat is also a quarter or less. I don't know where the tipping point is between tire traction and braking energy as the limiting factor, but as Garrett mentioned, the difference in stopping distances between smaller passenger cars and larger SUVs and pickup trucks widens dramatically from 60mph to 80mph, suggesting that energy becomes a factor even at those speeds.

Brake design plays a role. Drum brakes don't deal with energy as well as modern disk brakes. Two large brake disks on a sportbike will move more energy than a single small disk on a cruiser. More pad area pushed by more pistons will reduce lever effort on the part of the rider, making it easier to achieve the maximum braking force. The same factors in auto brakes will affect which auto can outbrake which motorcycle.

The limiting factor in a stop of a motorcycle may also not be the traction, but the stability of the vehicle. We've all seen sportbikes with the rear tire in the air in a stop. The front tire isn't sliding, so there may be still more traction available to slow, but any additional braking will just result in the motorcycle going over the front tire.

But with the assumption that stopping distance is limited by the traction of the tires, a = μg shows that the mass of the vehicle is not relevant; it does not enter into the equation. The only difference might be in the value of μ for car and bike tires. I had speculated that motorcycle tires have stickier rubber than auto tires, because of the difference in tire life. Softer rubber being stickier than harder rubber, and having a shorter life, it might follow that motorcycle tires are stickier than auto tires. But a reader, Blane Baysinger, pointed me to a Society of Automotive Engineers article comparing motorcycle and auto tires. This article indicates that the coefficient of friction of both auto and motorcycle tires is about 1.2 on dry surfaces (declining to .7 to .9 when skidding). The difference in longevity appears to be due to the greater amount of rubber on the auto tires; and it appears that if you can stop faster than a car, it's because you're better at using the brakes, not because of any inherent superiority in the braking capability of a motorcycle.

And there is one final complication: Can you use all the traction of your motorcycle tires? If you get too hard on the brakes in your car, you slide, you let off the pedal to resume rolling, you get back on the brakes. When the same thing happens on your motorcycle, the slide generally results in a fall. Thus motorcyclists are reluctant to approach the limit of their braking, where the same isn't true of auto drivers.

So where does this leave us? Here's my rule: I figure the guy in front of me is able to outbrake me, so I leave enough room between us, and look well ahead of him, so that I won't hit him. And I figure I can outbrake the guy behind me, especially if he's too close or not paying attention, so I leave even more room in front (to reduce the probability that I'll have to brake hard), and keep a close eye on my mirrors, and stay in the proper gear so that after braking hard I can escape if needed.
What do you think about antilock brakes?
Quite a few of my students are confused about what exactly antilock brakes do. A comment I've heard several times is "If I want the brakes pumped, I'll do it myself." That's a serious misunderstanding of what antilock brakes do. In fact, you don't want the brakes pumped. You want them applied as hard as possible, just short of the point where the tires begin to slide. That's where you get the greatest deceleration. The problem is that we humans have a hard time keeping the brakes at that point. The front tire, where nearly all of the braking power is, will slide if we brake too hard, requiring instant and dramatic action (namely, release of the brake) to prevent a fall. Many times we fail to react quickly enough, and crash. Or, fearing a fall, we don't apply the brakes hard enough and thus sacrifice some of our stopping distance.

Antilock brakes will not activate unless the rider makes the mistake of applying the brakes hard enough to lock a wheel. But if that happens, the machinery reacts more quickly than we can, releasing the pressure on the brakes to resume rolling and prevent a fall, followed more quickly than we can by reapplying the brakes to resume the stop.

The word from the experts at the motorcycle magazines, the people who do the 60-to-zero braking tests, is that under test conditions, they can outperform antilock brakes. That is, if their skills are already highly-developed, and if they have three or four tries to get tuned up, and if they know exactly when they're going to start braking, and if there are no traction surprises (like going over a sandy or painted patch of pavement), then they can outperform the machinery. But under real-world conditions, they say that antilock brakes win.

That's good enough endorsement for me. Furthermore, my guess is that over the next few years even test conditions won't be enough to outperform antilock brakes. Neither of my motorcycles has antilock brakes. My next motorcycle will have them.

(A post on another forum :Younglion)
 
#53 ·
Antilock brakes will not activate unless the rider makes the mistake of applying the brakes hard enough to lock a wheel. But if that happens, the machinery reacts more quickly than we can, releasing the pressure on the brakes to resume rolling and prevent a fall, followed more quickly than we can by reapplying the brakes to resume the stop.
I have the anti-lock brakes on my Road King, the salesman I had at the time suggested I go out and practice them as they feel very funny to use, I listened to him and every year I practiced them a couple of times. Then one day I got cut off in Texas, and in a panic hit the brakes really hard, they kicked in like they where supposed to and I rode them to a stop. I was amazed how short of a distance I actually went from 60 to 0. There is no way my car stops before hitting that guy.
 
#10 ·
Id agree that it really depends upon what car is used and what bike is used. Obviously, a Harley doesnt stop like a sportbike will.
Id like to see this test dont on a sportbike with ABS or with a skilled rider on a bike without ABS.
I still believe that all things being equal, a bike will stop faster than a car because its lighter.
 
#11 ·
Just throwing it out there.

Mission Viejo-based Motorcycle Consumer News is the only US motorcycle magazine that regularly tests braking performance. Here are their 10 best 60-0 stops from 2009.

motorcycle 60mph-0 stopping distance (ft)
Harley-Davidson XR1200 109.5
Ducati Monster 1100S 112.4
BMW K1300S (ABS) 113.0
Yamaha FZ6R 113.1
Triumph Street Triple R 114.6
Suzuki SFV650 Gladius 115.7
Moto Guzzi Griso 1200 8V 116.3
Triumph Bonneville 117.2
Aprilia Mana 850 117.4
Triumph 1050 Speed Triple 120.0

The big difference with car braking is that any bonehead can equal the test performance by just stomping on the pedal and letting the ABS modulate at impending lockup. With a motorcycle, it is much harder to do but ABS is slowly becoming available. I would guess that very few street riders can achieve the braking performance reported by MCN, which are done at a test track by a professional rider who tests dozens of different bikes a year. I know that I can't consistently brake at the threshold, and I don't practice that close to the limit of grip.

Maybe not a fair comparison but this is what the best cars are capable of.

93 FEET
2011 Chevrolet Corvette Z06 Carbon Edition
60-0 MPH: 93 ft
Tires: Michelin Pilot Sport Cup
Tire Size, Front: 285/30ZR19 87Y
Tire Size, Rear: 335/25ZR20 94Y
Brakes, Front: 15.5-in vented, drilled, carbon-ceramic disc/6-piston, ABS
Brakes, Rear: 15.0-in vented, drilled carbon-ceramic disc/4-piston,

Motor Trend Magazine.

A number of other cars are quite capable of 110 ft or less, but I'm not going to post them all. From my perspective bikes are fairly even with cars, I don't buy that bikes will cut the distance in half, which I have read elsewhere. All things being equal, and I did say equal, a car with excellent brakes will post the same distance and maybe a little less than a bike. Pitting a Kia Soul against a Ducati with Brembo's is not a fair comparison.
 
#18 ·
Mission Viejo-based Motorcycle Consumer News is the only US motorcycle magazine that regularly tests braking performance. Here are their 10 best 60-0 stops from 2009.

motorcycle 60mph-0 stopping distance (ft)
Harley-Davidson XR1200 109.5
Ducati Monster 1100S 112.4
BMW K1300S (ABS) 113.0
Yamaha FZ6R 113.1
Triumph Street Triple R 114.6
Suzuki SFV650 Gladius 115.7
Moto Guzzi Griso 1200 8V 116.3
Triumph Bonneville 117.2
Aprilia Mana 850 117.4
Triumph 1050 Speed Triple 120.0

The big difference with car braking is that any bonehead can equal the test performance by just stomping on the pedal and letting the ABS modulate at impending lockup. With a motorcycle, it is much harder to do but ABS is slowly becoming available. I would guess that very few street riders can achieve the braking performance reported by MCN, which are done at a test track by a professional rider who tests dozens of different bikes a year. I know that I can't consistently brake at the threshold, and I don't practice that close to the limit of grip.

Maybe not a fair comparison but this is what the best cars are capable of.

93 FEET
2011 Chevrolet Corvette Z06 Carbon Edition
60-0 MPH: 93 ft
Tires: Michelin Pilot Sport Cup
Tire Size, Front: 285/30ZR19 87Y
Tire Size, Rear: 335/25ZR20 94Y
Brakes, Front: 15.5-in vented, drilled, carbon-ceramic disc/6-piston, ABS
Brakes, Rear: 15.0-in vented, drilled carbon-ceramic disc/4-piston,

Motor Trend Magazine.

A number of other cars are quite capable of 110 ft or less, but I'm not going to post them all. From my perspective bikes are fairly even with cars, I don't buy that bikes will cut the distance in half, which I have read elsewhere. All things being equal, and I did say equal, a car with excellent brakes will post the same distance and maybe a little less than a bike. Pitting a Kia Soul against a Ducati with Brembo's is not a fair comparison.
Just as pitting a Harley against a Corvette isnt a fair comparison. Show me the braking distance of an R6, 600RR, GSXR, ZX, etc...
 
#12 ·
An there is an example Tobacco that I was talking about and just fined extremely hard to believe but I guess it has come to that point. A Corvette can stop shorter than a Harley. 93 ft. versus 112 ft. The weight difference would seem to say no way. But this example indicates that brakes have improved to the point it is possible. I just don't see the weight difference even coming close to twice the Harley of the Corvette to make this possible or even three times to allow for more contact patch on the road. Maybe I'm just over estimating the Corvette weight. It is these examples I've heard but don't have a source to see what the details are. I just can't get my head around it. Seems impossible to me but I can be thick headed.:D
 
#17 · (Edited)
For the members that have not read this article, you might enjoy it. Motor Trend and Cycle World took what are aurguably the highest performing production vehicles and pit them against one another. The Ducati out performed the Ferrari in most categories, including braking. And at a small fraction of the MSRP, we bikers get the best bang for the buck. http://www.motortrend.com/roadtests/exotic/1101_ferrari_458_italia_vs_ducati_1198_s/viewall.html

edit: It's fun reading the comments below the article. It's clear you are on a car website and not a motorcycle website when you read them.
 
#20 ·
I think whenever the opinion being given is by one side or the other of the parties involved in the test, it's always going to be a subjective opinion. I understand that and I take it with a grain of salt. In this test both are fine vehicles but it is comparing apples to oranges.
 
#25 ·
I did some reading in one of the many hotels I was in this past week and found some interesting data on Edmonds. It does in fact seem that most of the modern cars have stopping distances of around 100 feet 60 - 0. I found it hard to believe but the data was there. You have to search each vehicle independently to find the information in their testing. I looked up the mustang, charger, corvette and camaro. All stock, not the high end of the vehicle.
 
#30 ·
Wow! My XR1200 did that good? Motorcycle Consumer News (which I subscribe to) usually has the disclaimer in their test/review articles that those distances are by a PROFESSIONAL rider, not an average guy like most of us and most of those numbers are with ABS turned off if possible. ABS usually adds distance on average as most people will grab a handful that would cause an uncontrolled skid/slide otherwise not a controlled stop. My impression is that bike vs. car is pretty even depending on weight, meaning lighter bikes will perform like lighter cars given good brakes. A heavy bike like a Harley tourer would be like an SUV or large car, a lot longer distance. For my car brake distance tests I watch Motorweek on Public TV for examples. Cars also have four tires and brakes against two tires on a bike that are a lot skinnier giving less contact area.
 
#31 ·
I have no test results and no links. Let's start there. On the other hand my car has all of its brakes linked together so if a tire starts slipping the ABS will let off braking pressure on all wheels. On my bike the front and back brakes are separated. The ABS acts independently on each wheel so if the back starts to slip the front is not affected and vice versa. My guess is that in an emergency situation the independence of the ABS may become a significant factor in how far I go before I get stopped. That would mean the bike may well stop faster.
 
#32 · (Edited)
There are bikes with ABS last I heard....

I think it's a wash, small bike vs big car -- bike wins... Small car vs big bike, car wins.... But IMO it takes more skill to do it with most bikes...

I had to stop not long ago very hard (car) and there happened to be a 400 size bike not far behind me.. I did the stop and looked in the mirror to see how the bike did and he was totally in control and very much kept his distance....
 
#33 · (Edited)
I noticed on my new Fatboy, (having not had any previous HD experience) that the downshifting option for braking (belt drive) was a bit more dramatic, and I needed to float into the reductions a bit more than I had to on my chain-driven Shadow.

The brakes themselves do in fact work of course, and will stop that bike on a DIME if I'm not careful!! (They are not "ABS" however).

But to the original query, I'd assume the heavier weight of a car would require a longer stopping distance, than a motorcycle. Then again, from dead stop to start up, a bike is going to beat a car off the line, any day of the week!!

-Soupy
 
#55 ·
Then again, from dead stop to start up, a bike is going to beat a car off the line, any day of the week!!

-Soupy
Ah...but that is the crux. It depends.....

There are many cars these days faster than many motorcycles.

There are several motorcycles faster than the fastest cars.

Some bikes have poor brakes, some bikes have good brakes and some bikes have amazing brakes.

There are some cars that have amazing brakes. Ceramic rotors, huge rotors fantastic brake pads.

The mass market cars have decent brakes but they don't come close to state of the art. Same with many bikes.
 
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