So, here's the article I referred to in a previous post.
It has to do with the results of braking tests.
All, please do not misconstrue this new thread as an attempt to revive previous correspondence about the subject of 'brakes'.
My hat's off to 'busa's of every age and flavor.
==============================================
Reprinted from November 2007 Friction Zone is a monthly motorcycle magazine
CRASH SCIENCE
Motorcycle Handling Myth #1"â€A Motorcycle Stops on A Dime
by Dr. Voyko Banjac
Last month, I provided a brief outline of the four common motorcycle handling myths and why they are wrong. The first (and often the most dangerous) myth is the one associated with the perceived "Ëœextraordinary' stopping ability of a motorcycle. All of us have probably heard it at some point in time in our riding career: a motorcycle is so light, so responsive, so nimble, that all one has to do is pull (or stomp) on the brake lever, and the bike will instantaneously come to a dead stop. Not only that, but the motorcycle's braking ability leaves all other four-wheeled vehicles in the dust. Some will even venture so far as to state that a motorcycle is capable of such incredible braking speeds that it will have already come to a dead stop while the other vehicle (i.e., automobile, truck, SUV) is barely beginning to slow down.
Want the real truth? All those viewpoints are optimistic, unrealistic, and completely unfounded in science. Worst of all, they are wrong"â€and deadly. Their main fallacy is that they are based on a combination of expectation, "Ëœgut feeling,' and water-cooler talk"â€but not hard science. Similar to urban myths, these viewpoints are so pervasive and sufficiently believable that not many people stop and question their basis and accuracy. Since we are all familiar with how quickly motorcycles accelerate, we tend to naturally expect that they will decelerate just as quickly. Such expectations, unfortunately, can lead many riders to grossly underestimate the required stopping distance (and time) from a certain speed, leading to serious injury and death when the rider ends up colliding with an automobile or a roadside object.
The Science of Deceleration
As far as the world of science and physics is concerned, the bikes that we ride are nothing more than simple moving objects. The principles and equations that govern their deceleration are the same as those for other vehicles, humans, animals, falling objects, and basketballs. In other words, as much as some of us would like to think otherwise, motorcycles cannot violate the laws of physics. Not only that, but their deceleration can easily be measured with very accurate instruments, leaving no doubt as to the maximum amount of braking that a motorcycle can achieve.
The main equation that describes the deceleration of any object is
L braking = 0.033 x (v2/a)
where L braking denotes the braking distance in feet, v denotes the pre-braking speed in mph, and a denotes deceleration in Gs.
With the above equation, we can compare the required braking distance for virtually any kind of vehicle, from any speed if we know the deceleration that such a vehicle can achieve. The higher the G-force that a vehicle can achieve during deceleration, the more efficient its braking system and the shorter the total required braking distance. It's as simple as that"â€and there is no room left for "Ëœgut feeling' or urban myth.
Which Stops Quicker"â€Motorcycles or Automobiles?
Let's consider a motorcycle rider and an automobile driver, neck and neck, at the same position along a road and driving at a speed of 60 mph. At a certain point, they notice a dangerous condition ahead. Both drivers begin their perception/reaction (P/R) phase, wherein they scan the horizon, evaluate their options, and execute the chosen evasive maneuver. The P/R phase lasts for about a second or two, during which no action is carried out so the vehicles continue traveling forward at an unchanged speed of 60 mph. Upon completion of the P/R phase, both operators begin to slow their respective vehicles by engaging their braking systems, which in turn exert a frictional force between the tires and the pavement. Eventually both vehicles come to a full stop.
Which vehicle stops sooner?
Before we answer that question directly, we need to consider the two critical variables that can affect braking performance and braking distance. The first component, of course, is the vehicle's operator (the rider/driver). An alert, experienced, and highly trained operator can perceive a hazard quicker, initiate braking quicker, and actuate the brakes more efficiently. The second component is the vehicle. A modern vehicle with a quality braking system, especially with the benefit of ABS, stability and roll control, and similar safety features, can maximize the frictional force and reduce braking distance.
Assuming that both vehicles have top-notch operators (e.g., experienced performance riders/drivers), and that both vehicles are modern, high-capability machines, who will stop sooner?
The answer is not what we might expect. In general, the braking effectiveness of motorcycles and automobiles is very similar. But how is this possible? Doesn't this fly in the face of conventional "Ëœwisdom?' How can a big, bulky, heavy, four-wheeled automobile, let alone a lumbering SUV, match the braking of a small, light, nimble motorcycle?
The best sources for unbiased, accurate instrumented data for braking performance are road tests carried out by various international publications. The bar graphs show a sample selection of 60"“0 mph braking data and G force data for a wide variety of motorcycles, automobiles, and even SUVs. Let's compare two parameters: the braking distance from 60"“0 mph in feet, and the braking deceleration in Gs. As we can see, most automobiles and SUVs require about 110"“130 feet to stop, and achieve between "“0.90 and "“1.00 Gs"â€coincidentally, the same range of values achieved by motorcycles. High-performance sportbikes, such as the Ducati 999, Suzuki GSX1300R, and Honda CBR1000RR, can exceed "“1.00 Gs braking, but so can sports cars like the Porsche and Corvette, and even large sedans such as the BMW 7-series.
What about Real-Life Scenarios?
The above comparison involved highly trained, expert riders and drivers in optimum braking conditions. These braking tests were done in a straight line and under controlled circumstances: the rider/driver knew he would be applying the brakes. Regardless of what we may think of our capabilities, unless we diligently practice emergency braking techniques, most of us are quite far removed from such abilities. So, how do motorcycles and automobiles compare when it comes to everyday, real-life scenarios when emergency braking is required?
The worst-case scenario is an uncontrolled stop with a locked brake(s) and skidding wheel. Although both the motorcycle and the automobile are virtually uncontrollable in such cases, the automobile has one key benefit"â€it remains upright the entire time of the skid, and the driver usually doesn't have to worry about tipping the automobile over. An automobile skid can result in a deceleration of -0.5 to -0.7 Gs, while motorcycle skids often result in decelerations of -0.5 Gs"â€or lower if the bike tips over and slides on its side (e.g., engine or fairing) where there is much less friction and therefore a much longer braking distance.
A more optimistic "˜average' scenario involves emergency braking that is carried out skillfully enough so as not to compromise the control or the balance of either vehicle. Unfortunately, the modern automobile or SUV driver has a distinct advantage, as all he really has to do is mash the brake pedal as hard as he can. With ABS, stability control, traction control, and similar features present as standard equipment on virtually all cars sold in the U.S. today, even a mediocre driver can easily achieve decelerations of -0.90 or even -1.00 Gs. A motorcycle rider, on the other hand, is in charge of a vehicle devoid of virtually any kind of advanced safety feature (except for those bikes equipped with ABS). Not only that, but he is responsible for effective actuation of both the front and rear brake (unless his bike has linked braking) as well as working the clutch, controlling the handlebars, and ensuring the bike follows a straight line so as to minimize the chances of tipping. Therefore, an "˜average' emergency braking scenario for the average motorcyclist can range anywhere from about "“0.7 Gs to no more than about "“0.9 Gs.
Be Aware of Your Motorcycle's Limitations!
The most important lesson that we as riders need to remember is that our bikes are not capable of performing miracles. They are very complex machines that fall prey to the cruel laws of physics. When faced with an emergency situation, a motorcycle will not behave in the same way as an automobile. Unlike automobile drivers who can simply mash the brake pedal and let the car take care of everything, we have to perform multiple critical and coordinated tasks just to maintain control of our bike. In terms of braking, a motorcycle definitely doesn't stop on a dime"â€especially if the braking is not done while riding in a straight line. FZ
Reprinted from Friction Zone "¢ November 2007
CRASH SCIENCE
Reprinted with permission from Friction Zone, 60166 Hop Patch Spring Road, Mountain Center, CA 92561.
Automobile stopping distances courtesy of Road & Track. Motorcycle stopping distances courtesy of Motorcycle Consumer News.
It has to do with the results of braking tests.
All, please do not misconstrue this new thread as an attempt to revive previous correspondence about the subject of 'brakes'.
My hat's off to 'busa's of every age and flavor.
==============================================
Reprinted from November 2007 Friction Zone is a monthly motorcycle magazine
CRASH SCIENCE
Motorcycle Handling Myth #1"â€A Motorcycle Stops on A Dime
by Dr. Voyko Banjac
Last month, I provided a brief outline of the four common motorcycle handling myths and why they are wrong. The first (and often the most dangerous) myth is the one associated with the perceived "Ëœextraordinary' stopping ability of a motorcycle. All of us have probably heard it at some point in time in our riding career: a motorcycle is so light, so responsive, so nimble, that all one has to do is pull (or stomp) on the brake lever, and the bike will instantaneously come to a dead stop. Not only that, but the motorcycle's braking ability leaves all other four-wheeled vehicles in the dust. Some will even venture so far as to state that a motorcycle is capable of such incredible braking speeds that it will have already come to a dead stop while the other vehicle (i.e., automobile, truck, SUV) is barely beginning to slow down.
Want the real truth? All those viewpoints are optimistic, unrealistic, and completely unfounded in science. Worst of all, they are wrong"â€and deadly. Their main fallacy is that they are based on a combination of expectation, "Ëœgut feeling,' and water-cooler talk"â€but not hard science. Similar to urban myths, these viewpoints are so pervasive and sufficiently believable that not many people stop and question their basis and accuracy. Since we are all familiar with how quickly motorcycles accelerate, we tend to naturally expect that they will decelerate just as quickly. Such expectations, unfortunately, can lead many riders to grossly underestimate the required stopping distance (and time) from a certain speed, leading to serious injury and death when the rider ends up colliding with an automobile or a roadside object.
The Science of Deceleration
As far as the world of science and physics is concerned, the bikes that we ride are nothing more than simple moving objects. The principles and equations that govern their deceleration are the same as those for other vehicles, humans, animals, falling objects, and basketballs. In other words, as much as some of us would like to think otherwise, motorcycles cannot violate the laws of physics. Not only that, but their deceleration can easily be measured with very accurate instruments, leaving no doubt as to the maximum amount of braking that a motorcycle can achieve.
The main equation that describes the deceleration of any object is
L braking = 0.033 x (v2/a)
where L braking denotes the braking distance in feet, v denotes the pre-braking speed in mph, and a denotes deceleration in Gs.
With the above equation, we can compare the required braking distance for virtually any kind of vehicle, from any speed if we know the deceleration that such a vehicle can achieve. The higher the G-force that a vehicle can achieve during deceleration, the more efficient its braking system and the shorter the total required braking distance. It's as simple as that"â€and there is no room left for "Ëœgut feeling' or urban myth.
Which Stops Quicker"â€Motorcycles or Automobiles?
Let's consider a motorcycle rider and an automobile driver, neck and neck, at the same position along a road and driving at a speed of 60 mph. At a certain point, they notice a dangerous condition ahead. Both drivers begin their perception/reaction (P/R) phase, wherein they scan the horizon, evaluate their options, and execute the chosen evasive maneuver. The P/R phase lasts for about a second or two, during which no action is carried out so the vehicles continue traveling forward at an unchanged speed of 60 mph. Upon completion of the P/R phase, both operators begin to slow their respective vehicles by engaging their braking systems, which in turn exert a frictional force between the tires and the pavement. Eventually both vehicles come to a full stop.
Which vehicle stops sooner?
Before we answer that question directly, we need to consider the two critical variables that can affect braking performance and braking distance. The first component, of course, is the vehicle's operator (the rider/driver). An alert, experienced, and highly trained operator can perceive a hazard quicker, initiate braking quicker, and actuate the brakes more efficiently. The second component is the vehicle. A modern vehicle with a quality braking system, especially with the benefit of ABS, stability and roll control, and similar safety features, can maximize the frictional force and reduce braking distance.
Assuming that both vehicles have top-notch operators (e.g., experienced performance riders/drivers), and that both vehicles are modern, high-capability machines, who will stop sooner?
The answer is not what we might expect. In general, the braking effectiveness of motorcycles and automobiles is very similar. But how is this possible? Doesn't this fly in the face of conventional "Ëœwisdom?' How can a big, bulky, heavy, four-wheeled automobile, let alone a lumbering SUV, match the braking of a small, light, nimble motorcycle?
The best sources for unbiased, accurate instrumented data for braking performance are road tests carried out by various international publications. The bar graphs show a sample selection of 60"“0 mph braking data and G force data for a wide variety of motorcycles, automobiles, and even SUVs. Let's compare two parameters: the braking distance from 60"“0 mph in feet, and the braking deceleration in Gs. As we can see, most automobiles and SUVs require about 110"“130 feet to stop, and achieve between "“0.90 and "“1.00 Gs"â€coincidentally, the same range of values achieved by motorcycles. High-performance sportbikes, such as the Ducati 999, Suzuki GSX1300R, and Honda CBR1000RR, can exceed "“1.00 Gs braking, but so can sports cars like the Porsche and Corvette, and even large sedans such as the BMW 7-series.
What about Real-Life Scenarios?
The above comparison involved highly trained, expert riders and drivers in optimum braking conditions. These braking tests were done in a straight line and under controlled circumstances: the rider/driver knew he would be applying the brakes. Regardless of what we may think of our capabilities, unless we diligently practice emergency braking techniques, most of us are quite far removed from such abilities. So, how do motorcycles and automobiles compare when it comes to everyday, real-life scenarios when emergency braking is required?
The worst-case scenario is an uncontrolled stop with a locked brake(s) and skidding wheel. Although both the motorcycle and the automobile are virtually uncontrollable in such cases, the automobile has one key benefit"â€it remains upright the entire time of the skid, and the driver usually doesn't have to worry about tipping the automobile over. An automobile skid can result in a deceleration of -0.5 to -0.7 Gs, while motorcycle skids often result in decelerations of -0.5 Gs"â€or lower if the bike tips over and slides on its side (e.g., engine or fairing) where there is much less friction and therefore a much longer braking distance.
A more optimistic "˜average' scenario involves emergency braking that is carried out skillfully enough so as not to compromise the control or the balance of either vehicle. Unfortunately, the modern automobile or SUV driver has a distinct advantage, as all he really has to do is mash the brake pedal as hard as he can. With ABS, stability control, traction control, and similar features present as standard equipment on virtually all cars sold in the U.S. today, even a mediocre driver can easily achieve decelerations of -0.90 or even -1.00 Gs. A motorcycle rider, on the other hand, is in charge of a vehicle devoid of virtually any kind of advanced safety feature (except for those bikes equipped with ABS). Not only that, but he is responsible for effective actuation of both the front and rear brake (unless his bike has linked braking) as well as working the clutch, controlling the handlebars, and ensuring the bike follows a straight line so as to minimize the chances of tipping. Therefore, an "˜average' emergency braking scenario for the average motorcyclist can range anywhere from about "“0.7 Gs to no more than about "“0.9 Gs.
Be Aware of Your Motorcycle's Limitations!
The most important lesson that we as riders need to remember is that our bikes are not capable of performing miracles. They are very complex machines that fall prey to the cruel laws of physics. When faced with an emergency situation, a motorcycle will not behave in the same way as an automobile. Unlike automobile drivers who can simply mash the brake pedal and let the car take care of everything, we have to perform multiple critical and coordinated tasks just to maintain control of our bike. In terms of braking, a motorcycle definitely doesn't stop on a dime"â€especially if the braking is not done while riding in a straight line. FZ
Reprinted from Friction Zone "¢ November 2007
CRASH SCIENCE
Reprinted with permission from Friction Zone, 60166 Hop Patch Spring Road, Mountain Center, CA 92561.
Automobile stopping distances courtesy of Road & Track. Motorcycle stopping distances courtesy of Motorcycle Consumer News.
