Braking Capabilities of Motorcyclists - A Literature Review

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Hey everybody. This is my first attempt at a summary of the literature on the braking capabilities of motorcyclists, one small section for the motorcycle accident reconstruction book I'm working on with Lou Peck and William Neale. I would love to hear your comments on this - what is it missing? what do you like and not like?

Friction Coefficients for Motorcycle Tires

Motorcycle tires are softer and stickier than passenger car tires [Bartlett, 2001]. Lambourn and Wesley [2010] used a two-wheeled trailer (designed as a highway friction measuring device) to test three motorcycle tires designed for sports motorcycles to determine their peak and locked-wheel friction coefficients on asphalt (Figure 2‑1). They tested two different asphalt surfaces (hot rolled asphalt and stone mastic asphalt) in both a dry and a wet condition (1 mm water depth). The tires were tested at speeds of 32, 64, and 100 kph (20, 40, and 60 mph).

On dry, hot rolled asphalt, the motorcycle tires produced average peak friction coefficients between 1.1 and 1.3. These values generally increased with increasing speed. The average locked-wheel coefficients for dry, hot rolled asphalt ranged between 0.7 and 0.9. There was slight speed dependence in these values, with the friction coefficient declining slightly with increasing speed. On the dry, stone mastic asphalt, the motorcycle tires produced average peak friction coefficients between 1.1 and 1.25. There was no speed dependence in these values. The locked-wheel coefficients on the dry, stone mastic asphalt fell between 0.9 and 0.65. These values exhibited significant speed dependence, with the range at 32 kph falling between 0.8 and 0.9 and the range at 100 kph falling between 0.65 and 0.76.

On wet, hot rolled asphalt, the motorcycle tires produced average peak friction coefficients between 0.99 and 1.36. There was no obvious speed dependence in these values. The average locked-wheel coefficients on the wet, hot rolled asphalt showed significant speed dependence, falling between 0.8 and 0.9 at 32kph and 0.52 to 0.67 at 100kph. On the wet, stone mastic asphalt, the motorcycle tires produced average peak friction coefficients between 1.0 and 1.15. The locked-wheel coefficients exhibited significant speed dependence, falling between 0.68 and 0.76 at 32 kph and between 0.37 and 0.4 at 100 kph.

Motorcyclist Braking and Deceleration Capabilities

Tolhurst and McKnight [1986] tested and compared five methods of braking in a straight line and three methods of braking in a curve. For all eight methods, the rider applied the front brake to the maximum extent possible without locking the wheel. The level of rear wheel braking was varied. For the straight line braking tests, which were run from a nominal initial speed of 40 mph, the level of rear wheel braking was varied as follows: no rear wheel braking, light rear wheel braking, locked rear wheel braking, pumping of the rear brake, and heavy rear wheel braking just below the level necessary to lock the wheel. For the braking in a curve tests, which were run from a nominal initial speed of 30 mph, the level of rear wheel braking was varied as follows: no rear wheel braking while keeping the motorcycle leaned, heavy rear wheel braking while keeping the motorcycle leaned, and heavy rear wheel braking while righting the motorcycle.

This study utilized three expert riders operating three different motorcycles – a Yamaha FJ1100 (a sport touring bike with an approximately 1,200 cc engine), a Yamaha 550 Vision (a sport touring bike with an approximately 500 cc engine), and a Suzuki GS 550 (see Figure 2‑2). For the straight line braking, the heavy rear wheel braking (below the level necessary to lock the wheel) produced the highest deceleration rate and the shortest stopping distance. The lowest deceleration rates and longest stopping distances resulted when the rear brake was not applied at all. For braking in a curve, the highest deceleration rates and shortest stopping distances were achieved by righting the motorcycle while applying heavy braking to both brakes (without locking the wheels). The lowest deceleration rates and longest stopping distances were generated by continuing to lean in the curve and not applying the rear brake at all.

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Prem [1987] conducted emergency, straight line braking tests with 59 volunteer riders. He used the Motorcycle Operator Skill Test (MOST) to provide a quantitative assessment of the riders’ skill level. The MOST takes the riders through a series of tasks designed to test their steering and braking performance. The braking maneuver analyzed by Prem was a part of the MOST and it was a task that required the riders to brake aggressively to a stop from a speed of 32 kph. A red signal light was activated to indicate to the riders when they should begin braking. The motorcycles used by the volunteers were instrumented to record the rider’s front and rear brake-lever force inputs and motorcycle speed.

Prem was interested in determining assessing the differences in braking technique between skilled and less-skilled riders. Prem found that skilled riders applied higher levels of front brake force than the less-skilled riders. Less-skilled riders preferred the use of the rear brake. The skilled riders also modulated the level of front and rear wheel braking to maintain optimum braking as weight shifted towards the front of the motorcycle during heavy braking. The less-skilled riders maintained a generally constant level of level and pedal pressure independent of the weight shift. More skilled riders also exhibited shorter braking reaction times.

Fries, Smith, and Cronrath [1989] performed testing with five different motorcycles to determine the deceleration rate of the motorcycles when the rider employed the rear brake only and when the rider employed a combination of front and rear wheel braking. They tested a 1968 Harley-Davidson FLH, a 1978 BMW R90, a 1982 Honda XR500R, a 1972 Honda SL350, and a 1972 Honda SL125S trail bike. Each motorcycle was tested at nominal speeds of 20, 30, and 40 mph on worn asphalt. Overall, the deceleration rates from rear wheel only braking were less than when heavy front wheel braking was also used. The range of deceleration rates for rear wheel only braking was 0.31 to 0.52g. The range of deceleration rates achieved by the riders when they also employed heavy front wheel braking was between 0.54 and 0.88g.

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Based on the results of his testing, Fries states that “when faced with an emergency stopping situation, or avoidance situation, a motorcycle [rider] has the decision of whether to stop using the rear brake only, front and rear brakes combined, or by laying the motorcycle down. There are several common misconceptions about motorcycles. One is that they will stop faster if they are laid down on their side…When a motorcycle is stopped by laying it on its side there is a delay in implementing the deceleration…The test results show that laying a motorcycle over and rear wheel braking have very similar deceleration factors. However, when laying a motorcycle over there is an impact and risk of injury when the motorcycle hits the pavement. Also, all control is lost. If the motorcycle is kept upright, it is possible to reduce braking and steer. Front and rear wheel braking provides the best deceleration factors. Our testing also demonstrates that even during hard braking with front and rear brakes, the experienced driver consistently maintained a straight path without causing the motorcycle to fall…When a motorcycle rider is presented with an accident situation, proper use of front and rear brakes will produce the most effective stopping…Laying the bike down results in impact with pavement, total loss of control, and a longer stopping distance.”

Hunter [1990] reported acceleration and braking tests conducted by the Washington State Patrol on a dry, level roadway with a 1983 and a 1985 Kawasaki 1000 police motorcycle (Figure 2‑4). For deceleration tests with rear braking only, Hunter reported deceleration rates between 0.35 and 0.36g. For deceleration tests with front braking only, Hunter reported deceleration rates between 0.64 and 0.74g. For deceleration tests with heavy front and rear braking, Hunter reported deceleration rates between 0.63 and 0.96g. For the rapid acceleration tests, Hunter reported acceleration rates between 0.48 and 0.73g.

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Hugemann and Lange conducted 74 instrumented braking experiments with 18 different riders, 15 of whom were on their own motorcycle. The riders had varying levels of experience (less than 12,500 miles up to 80,000 miles), and were instructed to brake from 50 kph (31 mph) to a standstill “within the shortest possible distance.” Riders characterized as “skilled” and “novice” exhibited braking rates of 0.77 and 0.49 g’s, respectively.

Bartlett [2000] reported testing with four motorcycles – a Harley-Davidson FXRT, a Yamaha FZ600, a Suzuki Katana 750, and a Kawasaki EX650 (Figure 2‑5). For tests that utilized only the rear brake, the maximum deceleration rates between these four motorcycles varied between 0.38 to 0.46g. For tests that utilized only the front brake, the maximum deceleration rates varied between 0.88 and 0.89g. Bartlett reported testing with combined front and rear braking only for the Harley-Davidson. This produced a maximum deceleration rate of 0.96g. In this testing, the Yamaha brake pads were deteriorated, resulting in metal-to-metal contact. The maximum deceleration rate produced with the Yamaha with these deteriorated brake pads was 0.75g.

Ecker and his colleagues conducted a study comprised of 600 tests performed by 300 riders of varying levels of experience (novice to 40+ years) operating an instrumented Honda CB500 [2001]. The motorcycle used in this testing is depicted in Figure 2‑6. As the riders were operating the Honda around a training facility, the test coordinator would trigger a red light mounted to the instrument cluster, signaling the rider to “make a full stop emergency braking maneuver.” The average braking rate for all 600 runs was 0.63g with a standard deviation of 0.12g. So, assuming a normal distribution, these figures suggest a 68% confidence interval of 0.51 to 0.75g. Another interesting conclusion of this study was that there was only a very minor correlation between braking ability and riding experience, especially for more than 1 year of experience. They also found that half of the participants exploited 56% or less of possible performance, and that locking occurred quite often.

 

Vavryn [2004] examined the efficacy of antilock braking systems (ABS). Vavryn reported the results of 800 tests performed with 181 subjects on two different motorcycles. The riders were asked to “come to a complete stop as soon as possible without falling off the vehicle.” Initial speeds were either 50 or 60 kph (31 or 37 mph), and the subjects performed two tests on their own motorcycle, and then two runs on a motorcycle equipped with ABS. One of the ABS bikes was a standard BMW, while the other was a scooter equipped with linked ABS. The average braking rate for motorcyclists on their own motorcycle was 0.67 g (SD = 0.14g). However, when riding the motorcycles equipped with ABS, that number jumped up to 0.80g (SD = 0.11g). Eighty five percent of the subjects exhibited improved braking with the ABS-equipped motorcycle and the novice riders achieved almost equal braking rates to the experienced riders when operating the ABS-equipped motorcycles.

 Bartlett, Baxter, and Robar [2007] reported hundreds of brake tests from reconstruction classes conducted at the Institute of Police Technology and Management (IPTM) from between 1987 and 2006. These tests were conducted at various locations around the country with 112 different motorcycles and riders. They were all conducted on dry asphalt or concrete. Initial speeds in the tests were nominally 20, 30, and 40 mph. The riders in these tests were typically motorcycle unit officers or instructors from a police agency. The data set in this study included 275 rear brake only tests, 239 front brake only tests, and 221 tests with combined front and rear braking. This data set yielded the conclusion that the deceleration rates were normally distributed with a mean and standard deviation for the rear only braking of 0.37g ± 0.06g, with front only braking of 0.60g ± 0.16g, and with combined front and rear wheel braking of 0.74g ± 0.15g.

Bartlett and Greear [2010] presented brake test data from students in a motorcycle training program (Skills Training Advantage for Riders from the State of Idaho) with three skill levels – Basic I, Basic II, and Experienced. The authors note that “the Basic I program is for rider who are new to motorcycling, with virtually no experience, and is conducted on STAR training motorcycles. These bikes are typically 250cc or smaller, with front disc and rear drum brakes. The Basic II program is for riders who are returning to motorcycling or those who have ridden on dirt, but not on the street, i.e., riders with some experience but not much on street cycles. These riders also use the program’s training motorcycles. The Experienced program is for riders who have been riding for more than one year, and is conducted using the riders’ own motorcycles.”

In this training program, the conclusion of each level included a riding skills test, which included a stopping test. Riders were instructed to approach the stopping area at a steady speed between 15 and 20 mph. Once in the stopping area, they were to stop the motorcycle as quickly as they could with maximum braking. Bartlett reported the results of 288 total tests. The results of these tests “were almost indistinguishable” for the three skill levels. The Basic I group produced deceleration rates with a mean and standard deviation of 0.60g ± 0.16g, the Basic II group produced deceleration rates of 0.64g ± 0.14g, and the Experienced group produced deceleration rates of 0.61g ± 0.14g. The authors note: “The application of this work to reconstruction should not be viewed as a means to interpret speed based on skidmarks. Skidding friction values, to be used when there are marks to measure, have been discussed at length in other articles and publications. Rather, this data should be applied to those circumstances when one is attempting to evaluate how a rider performed or could have performed, given situationally appropriate time and distance limitations based on the scene and circumstances of the event under consideration.”

Dunn [2012] reported and analyzed braking test data and tire marks for the three motorcycles depicted in Figure 2‑7 – a 1995 BMW R1100RS (sport-touring with anti-lock brakes), a 2003 Buell XB9R (sport), and a 2005 Harley-Davidson XL 1200 Sportster Custom (cruising/touring). They tested three different braking strategies – best effort front braking only, best effort rear braking only, and best effort front and rear combined braking. Initial speeds for the testing were nominally 25, 45, and 60 mph and most of the tests were conducted on a flat, dry asphalt surface. One set of tests on wet asphalt were run with the BMW, a motorcycle equipped with anti-lock brakes.

For the BMW, the rear braking only strategy produced deceleration rates between 0.364 and 0.416. The front braking only strategy produced deceleration rates between 0.671 and 0.828. The combined front and rear braking strategy produced deceleration rates between 0.642 and 0.842. For all three strategies, the deceleration rates increased with increasing speed. On the wet asphalt surface, the BMW produced deceleration rates with both brakes between 0.637 and 0.827. For the Buell, the rear braking only strategy produced deceleration rates between 0.345 and 0.380. The front braking only strategy produced deceleration rates between 0.548 and 0.709. The combined front and rear braking strategy produced deceleration rates between 0.612 and 0.708. Again, for all three strategies, the deceleration rates increased with increasing speed. For the Harley-Davidson, the rear braking only strategy produced a deceleration rate of 0.386 (this strategy was only tested at 45 mph). The front braking only strategy produced a deceleration rate of 0.518 (this strategy was only tested at 45 mph). The combined front and rear braking strategy (tested at 45 and 60 mph) produced deceleration rates between 0.658 and 0.674.

Dunn found that “at the extreme, the rear tire of the Buell lifted off the ground in some tests” (Figure 2‑8). Frank [2008] noted that “pitch-over events are common in motorcycle accidents, and can be caused by impact to the front wheel and occasionally by hard brake application…Provided there is sufficient tire/road friction, at the limit of the braking capacity of the motorcycle the weight on the rear tire is zero. Though not inevitable, this is the point at which the motorcycle can pitch-over.” Frank conducted 18 sled tests to evaluate the trajectory and velocity of riders and passengers on motorcycles that pitched over due to braking. This testing used target deceleration rates of 1.0, 1.15, and 1.3g, significantly higher deceleration rates than what could be achieved by most riders. Target speeds for the testing were 20, 30, and 33.5 mph. The lowest braking deceleration rate that produced a pitch-over in Frank’s testing was 1.0g with a test speed of 30.2 mph.

 

In 2017, Peck and Deyerl examined the effect of tire pressure on the deceleration rate achieved with full application of the rear brake only. This testing utilized a 2003 Suzuki GSF1200 equipped with Michelin Pilot Road radial tires (Figure 2‑9). The tests were run from a nominal speed of 30 mph – three tests with the rear tire at 40 psi and three tests with the rear tire at 20 psi. The front tire was inflated to the manufacturer recommended tire pressure of 36 psi for all of the tests. Peck and Deyerl documented the size of the tire contact patch by using a rear swingarm stand to suspend the rear tire above a piece of brown paper, putting paint on the tire, and then lowering the tire onto the paper. The size of the rear tire contact patch was 46% larger at 20 psi than at 40 psi and the average deceleration rate was 5% greater at 20 psi than at 40 psi. For the tests at 40 psi, the three tests yielded the following deceleration rates (g): 0.324, 0.321, 0.327 (average = 0.324). For the tests at 20 psi, the three tests yielded the following deceleration rates (g): 0.341, 0.339, 0.338 (average = 0.339). These findings by Peck and Deyerl are consistent with results reported by others for passenger cars [Baumann, 2009; Rievaj, 2013].

Table 2‑1 summarizes the deceleration rates from the studies that this section has reviewed.

These deceleration rates are often applied for calculating a motorcycle’s speed loss due to braking by the operator. For many crashes, the braking precedes an impact and there may be zero, one, or two tire marks deposited by this braking.

Motorcycles with Integrated, Linked, and Antilock Braking Systems

For a standard motorcycle braking system, the lever on the right handlebar controls the front brake and the right side pedal controls the rear brake. For an integrated braking system, the lever on the right handlebar actuates the front brake only and the right side pedal actuates both the front and the rear brakes. For an independent, antilock braking system, the front and rear brakes are controlled independently, but the antilock system prevents the operator from locking either wheel. For an integrated antilock braking system, both brakes are applied regardless of which lever is used and the antilock system prevents either wheel from locking. For a linked braking system, found only on Honda motorcycles, application of the right hand lever or pedal will actuate both the front and rear brakes. The proportioning of the brakes varies with the lever that is used.

Baxter and Robar [2007] observed that “the integrated brake system is not very popular with experienced riders. Many operators like to have the option of independent braking on their machines, particularly on surfaces such as gravel and other loose material. Owners unhappy with the integrated systems often replace the integrated parts with parts from sister models that use the standard brake components.” Baxter and Robar noted that, in 1988, BMW became the first manufacturer to offer a motorcycle with an antilock brake system. Yamaha followed in 1991 and Honda in 1996. Baxter and Robar noted that, starting in 2003, Ducati offered an antilock brake system with an on-off switch, giving the operator control over whether the ABS system is active or not. BMW also offered an on-off switch on some of their models. In 2008, Harley-Davidson began offering an optional ABS system with independently controlled front and back brakes.

Studies of the Effectiveness of Integrated, Linked, and ABS Brakes

Mortimer [1986] examined the effectiveness of integrated brakes (without ABS). His testing utilized a 1979 Yamaha XS-400 with standard brakes as the original equipment and a 1982 Yamaha XS-1100 with integrated brakes as the original equipment. Mortimer modified both motorcycles so that they could be operated in either a standard braking mode or an integrated braking mode. The integrated mode on the XS-400 could only be operated with the right side rear brake foot pedal. On the XS-1100, the integrated braking would be activated with either the right side foot pedal or hand lever. Five experienced, but not expert, riders were used in Mortimer’s testing. Tests were run from a nominal speed of 25 mph (40.3 kph) and the riders attempted to stop the motorcycle in as short a distance as possible. Each rider performed testing on each motorcycle and they made five stops in each test condition. The tests were run with the hand brake only, the foot brake only, and then both.

Mortimer noted that “the stopping distances were directly measured at the point where the motorcycle came to a stop in terms of the distance from the cones marking the entrance to the braking course. The stopping distance was translated into the mean deceleration during the stop, assuming an initial speed of 40.3 km/h.” This manner of measuring the stopping distance and deceleration rate is prone to error since there is no way to know, in any given instance, if the riders actually began braking at the cone or to know that the rider started braking from a speed of precisely 40.3 kph (25 mph). Mortimer found the greatest benefit from integrated brakes for the condition of braking with the foot pedal only. He noted that “use of the foot brake alone of the XS-400 motorcycle produced a 72% greater mean deceleration in the integrated than the separated mode. Similarly, use of the foot brake of the XS-1100 motorcycle in the integrated mode produced a 50% increase in mean deceleration compared with the separated mode…In addition, when both brakes were used on the larger motorcycle there were significant and consistent increases in deceleration obtained on both the dry and wet pavements in the integrated mode compared with the separated mode, but the increments were not as large as those found for the operation of the foot brake alone.”

Vavryn [2004] examined the efficacy of antilock braking systems (ABS). Vavryn reported the results of 800 tests performed with 181 subjects on two different motorcycles. The riders were asked to “come to a complete stop as soon as possible without falling off the vehicle.” Initial speeds were either 50 or 60 kph (31 or 37 mph), and the subjects performed two tests on their own motorcycle, and then two runs on a motorcycle equipped with ABS. One of the ABS bikes was a standard BMW, while the other was a scooter equipped with linked ABS. The average braking rate for motorcyclists on their own motorcycle was 0.67 g (SD = 0.14g). However, when riding the motorcycles equipped with ABS, that number jumped up to 0.80g (SD = 0.11g). Eighty five percent of the subjects exhibited improved braking with the ABS-equipped motorcycle and the novice riders achieved almost equal braking rates to the experienced riders when operating the ABS-equipped motorcycles.

Green reported a test program conducted by NHTSA, in cooperation with Transport Canada (TC), “to assess the effectiveness of anti-lock braking systems (ABS) and combined braking systems (CBS) on motorcycles” [2006]. Six motorcycles were tested on both dry and wet asphalt – a 2002 Honda VFR 800 with ABS and CBS, a 2002 BMW F650 with ABS, a 2002 BMW R 1150R with ABS and CBS, a 2002 BMW R 1150R without ABS or CBS, a 2004 Yamaha FJR1300 with ABS, and a 2004 Yamaha FJR1300 without ABS. Green observed that, with ABS, “the stopping distances were very consistent from one run to another.” Without ABS, “the stopping distances were less consistent because the rider while modulating the brake force, had to deal with many additional variables at the same time…Test results from non-ABS were noticeably more sensitive to rider performance variability.” On average, ABS reduced the stopping distances by approximately 5%.

Rizzi, et al., evaluated the effectiveness of motorcycle antilock brakes at reducing crashes in Spain, Italy, and Sweden [2009]. Rizzi noted that the European Parliament has made ABS mandatory for all new motorcycles over 125cc, effective in 2016. Using police-reported crashes from 2006-2009 in Spain, 2009 in Italy, and 2003-2012 in Sweden, Rizzi concluded that “the effectiveness of motorcycle ABS in reducing injury crashes ranged from 24% in Italy to 29% in Spain and 34% in Sweden…The reduction of severe and fatal crashes was even greater, at 34% and 42% in Spain and Sweden, respectively.”

 Anderson, Baxter, and Robar [2010] reported deceleration rate testing of motorcycles with the following different braking systems: standard brakes (1990 Harley Davidson Road King FLHTPI), integrated brakes without ABS (1986 Yamaha Venture Royale XVZ13), independent ABS brakes (1999 BMW R1100RPT), integrated ABS brakes, and linked brakes (2003 Honda VFR800 Interceptor). The authors tested each of these systems on an asphalt surface with application of the rear pedal only, the front lever only, and with both levers applied. The initial speed for the tests was approximately 56 kph. All of the tests utilized the same operator with many years of riding experience. The authors noted that “there was no wheel lockup or skidding during any of the tests runs.” The table below summarizes the results of the testing for each braking system.

Anderson, Baxter, and Robar concluded that “motorcycle braking systems that actuate both front and rear brakes with the application of only one control lever produce more effective braking than independent front and rear brakes on a standard system. When combined with anti-lock control the benefits of the combined system are increased. Perhaps more importantly, however, is that the motorcycle is also more stable during the braking maneuver. The increased stability along with the simplified brake application combine to reduce the load on the operator during the stressful moment of hard braking to avoid a crash. The operator does not have to concentrate on modulating pressure between two separate controls and simultaneously keep the motorcycle stable and prevent the wheels from locking, as the system performs these functions and permits the operator to focus on avoiding the crash.”

Basch, Moore, and Hellinga examined the effectiveness of motorcycle antilock braking systems in terms of crash rates [2015]. They noted that while prior studies had reported lower crash rates for motorcycles equipped with ABS, these studies had not considered the possibility that safer riders are more likely to purchase motorcycles equipped with ABS, and thus, riders with ABS-equipped motorcycles were already less likely to crash. In this study, insurance auto claim frequency was used as a proxy for the crash risk of individual riders. The authors concluded, first, that “there was no evidence that safer riders, as measured by auto claim frequency, were more likely to purchase motorcycles with optional ABS. Rather, riders with higher auto claim frequencies were more likely to ride motorcycles with ABS.” Further, they concluded that “after controlling for auto claim frequency, motorcycles equipped with optional ABS were associated with a 21 percent reduction in claim frequency compared with similar motorcycles without ABS.”

References

1.     Anderson, B., Baxter, A., Robar, N., “Comparison of Motorcycle Braking System Effectiveness,” SAE Technical Paper 2010-01-0072, 2010, doi:10.4271/2010-01-0072.

2.     Bartlett, Wade, “Motorcycle Braking and Skidmarks,” Mechanical Forensics Engineering Services, LLC., 2000.

3.     Bartlett, Wade, “Interpretation of Motorcycle Rear-Wheel Skidmarks for Accident Reconstruction,” Proceedings, Fourth International Conference on Accident Investigation, Reconstruction, Interpretation and the Law, Vancouver BC, Canada, August 2001.

4.     Bartlett, Wade, Baxter, Al, Robar, Neil, “Motorcycle Braking Tests: IPTM Data Through 2006,” Accident Reconstruction Journal, July/August 2007.

5.     Bartlett, Wade, Greear, Charlie, “Braking Rates for Students in a Motorcycle Training Program,” Accident Reconstruction Journal, Volume 20, No. 6, November/December 2010.

6.     Basch, Nicholas, Moore, Matthew, Hellinga, Laurie, “Evaluation of Motorcycle Antilock Braking Systems,” The 24th Enhanced Safety of Vehicles Conference, Paper Number 15-0256, 2015.

7.     Baumann, Frank W., Schreier, H., Simmermacher, D., “Tire Mark Analysis of a Modern Passenger Vehicle with Respect to Tire Variation, Tire Pressure and Chassis Control Systems,” SAE Technical Paper 2009-01-0100, doi:10.4271/2009-01-0100.

8.     Baxter, A., Robar, N., “An Examination of the Performance of Motorcycle Brake Systems,” Accident Investigation Quarterly, (47):28-31, 2007.

9.  Cossalter, Vittore, Lot, R., Maggio, F., “On the Braking Behavior of Motorcycles,” SAE Technical Paper Number 2004-32-0018, 2004, doi:10.4271/2004-32-0018.

10.  Cossalter, Vittore, Motorcycle Dynamics, Second Edition, 2006.

11.  Dunn, A.L., et al, “Analysis of Motorcycle Braking Performance and Associated Braking Marks,” SAE Technical Paper 2012-01-0610, 2012, doi:10.4271/2012-01-0610.

12.  Ecker, H., Wasserman, J., Hauer, G., et al., “Braking Deceleration of Motorcycle Riders,” International Motorcycle Safety Conference, Orlando, 2001.

13.  Frank, T., Smith, J., Hansen, D., and Werner, S., "Motorcycle Rider Trajectory in Pitch-Over Brake Applications and Impacts," SAE Int. J. Passeng. Cars - Mech. Syst. 1(1):31-42, 2009, doi:10.4271/2008-01-0164.

14.  Fricke, Lynn B., Traffic Crash Reconstruction, Second Edition, Northwestern University Center for Public Safety, 2010.

15.  Fries, T.R., Smith, J.R., Cronrath, K.M., “Stopping Characteristics for Motorcycles in Accident Situations,” SAE Technical Paper 890734, 1989, doi:10.4271/890734.

16.  Green, Donovan, “A Comparison of Stopping Distance Performance for Motorcycles Equipped with ABS, CBS and Conventional Hydraulic Brake Systems,” USDOT, NHTSA, International Motorcycle Safety Conference, March 2006.

17.  Hugemann, W., Lange, F., “Braking Performance of Motorcyclists,” 1993.

18.  Hunter, John E., “The Application of the G-Analyst to Motorcycle Acceleration and Deceleration,” SAE Technical Paper 901525, 1990, doi:10.4271/901525.

19.  Hurt, H.H., “Motorcycle Accident Cause Factors and Identification of Countermeasures, Volume I: Technical Report,” Prepared for the U.S. Department of Transportation, January 1981.

20.  Hurt, H.H., “Human Factors in Motorcycle Accidents,” Paper Number 770103, Society of Automotive Engineers, 1977.

21.  Lambourn, Richard F., Anna Wesley, “Motorcycle Tire/Roadway Friction,” Paper Number 2010-01-0054, Society of Automotive Engineers, 2010.

22.  Mortimer, R., “Braking Performance of Motorcyclists with Integrated Brake Systems,” SAE Technical Paper 861384, 1986, doi:10.4271/861384.

23.  Peck, Louis, Deyerl, Eric, Rose, Nathan, “The Effect of Tire Pressure on the Deceleration Rate of a Motorcycle Under Application of the Rear Brake Only,” 2017, forthcoming.

24.  Prem, Hans, “The Emergency Straight-Path Braking Behaviour of Skilled versus Less-skilled Motorcycle Riders,” SAE Technical Paper 871228, 1987, doi:10.4271/871228.

25.  Rievaj, Vladimir, Vrabel, Jan, Hudak, Anton, “Tire Inflation Pressure Influence on a Vehicle Stopping Distances,” International Journal of Traffic and Transportation Engineering 2013, 2(2):9-13, doi:10.5923/j.ijtte.20130202.01.

26.  Rizzi, M., Strandroth, J., Tingball, C., “The Effectiveness of Antilock Brake Systems on Motorcycles in Reducing Real-Life Crashes and Injuries,” Traffic Injury Prevention, 10:479-87, 2009.

27.  Tolhurst, N. and McKnight, A., "Motorcycle Braking Methods," SAE Technical Paper 860020, 1986, doi:10.4271/860020.

28. Vavryn, K., Winkelbauer, M., “Braking Performance of Experienced and Novice Motorcycle Riders – Results of a Field Study,” International Conference on Traffic & Transport Psychology, 2004.

About Nathan

Nathan is an accident reconstruction expert at Kineticorp. He is dedicated to mastering his craft, and for the past 20 years, he has dedicated himself to research and writing as a means of developing authentic expertise that provides real value to juries. Nathan developed this article as part of the research that will ultimately make it into his book on motorcycle accident reconstruction.