Motorcycle Brake Testing in U.S.A.
Conducted by DOT (Department of Transport) and NHTSA (National Highway Traffic Safety Administration.)
George J. Soodoo © 2002
Introduction
The purpose of the research was to assess state of motorcycle braking performance. We tested motorcycles in each of 5 categories: Sport, Cruiser, Touring, Dual Purpose, Scooter. Performance was evaluated with application of front brake, rear brake, and both brakes together. We also evaluated antilock brake system (ABS) on Touring bike and linked braking system (LBS) on Sport bike.
Motorcycle Crashes 1990-1999
Over-40 age group accounted for 39% of fatalities in single vehicle crashes in 1999, up from 14% in 1990. 42% of all age group fatalities involved intoxicated riders. Bikes with engine displacement above 1000 cc were involved in 33% of fatalities in 1999, up from 22% in 1990
Single vehicle crashes account for about 45% of all motorcycle fatalities
Crash Avoidance Maneuvers (Steps rider took to avoid crash)
22% of motorcycle fatalities were related to braking or steering maneuvers. Fatalities related to braking has fluctuated slightly between 1990 and 1999 but remains at 13%.
30% of fatalities were attributed to no maneuver taken to avoid crash. One-half of the motorcycle fatalities occurred when the vehicle was negotiating a curve
NHTSA Plans
To understand causes of increased motorcycle fatalities by additional crash data analysis and to understand role crash avoidance systems play in potential crash reduction.
To continue research in order to evaluate brake system performance seeking ways to improve brake performance through harmonization and/or upgrade of FMVSS 122
Test Vehicles
Sport: Honda VRF800F with linked braking system (LBS)
Cruiser: Harley-Davidson Superglide Sport
Touring: BMW R1100 RT with antilock braking system (ABS)
Dual Purpose: Kawasaki KLR 650
Scooter: Yamaha Riva 125
Braking Test Maneuvers
30 mph – 48 kmh on Dry Asphalt SN 85
60 mph – 97 kmh on Dry Asphalt SN 85
80 mph – 130 kmh on Dry Asphalt SN 85
30 mph – 48 kmh on Wet Asphalt SN 55
30 mph – 48 kmh on Polished Concrete
30 mph – 48 kmh in a corner on Dry Asphalt
30 mph – 48 kmh on Dry Belgian Block
30 mph – 48 kmh on Wet Belgian Block
30 mph– 48 kmh on Dry Asphalt with wetted brakes
Brake Fade and Recovery Evaluation
Evaluation Criteria
Brake temperatures
Brake lever/pedal application load
Average Stopping distance
Dry Asphalt – 30 mph– 48 kmh
RESULTS
Braking Dry Asphalt – 30 mph– 48 kmh
ABS bike had shortest stop with front brake applied
LBS bike had shortest stop with rear brake applied
ABS bike had shortest stop with both brakes applied
With LBS off, rear only braking produced longest stop
Scooter had longest stops in all three segments, when compared with other bikes with systems operational
Braking Dry Asphalt – 60 mph– 97 kmh
LBS bike had shortest stops with front, rear, and combined brake application
LBS uses both front and rear brakes even when one lever/pedal is applied
Performance tires on Sport bike with LBS also helped stopping distance performance
Braking Dry Asphalt – 80 mph– 130 kmh
Only ABS and LBS bikes tested from this speed
ABS bike had shorter stop with front brake application and also with both brakes applied
When rear pedal alone was used, LBS bike performed better than the ABS bike
LBS bike exhibited consistently short stops regardless of whether front, rear or both brakes were applied
Braking Wet Asphalt – 30 mph– 48 kmh
ABS bike had shortest stop when either front brake or both brakes were applied
ABS bike had highest brake application load due to increased rider confidence in ABS
Braking Dry Polished Concrete – 30 mph– 48 kmh
Surface has lower coefficient of friction than dry asphalt
ABS equipped bike outperformed other bikes, with front or both brakes applied
Driver is able to make a hard brake application without concern for wheel lockup since ABS optimizes brake force for given road surface
Braking in a Corner – 30 mph– 48 kmh
Curve: 200-ft radius on dry asphalt
Sport bike with LBS had shortest stop for rear brake application only
Touring bike with ABS had shortest stops when front or both brakes applied
ABS increased rider confidence. However, during ABS activation, it was difficult for rider to maintain lane position due to different ABS modulation on front and rear wheels.
Conclusions – ABS Considerations
Touring bike with ABS did not show a clear advantage when braking in straight line stops.
ABS improved rider confidence when braking on wet or curved surface because system prevents wheel lockup In panic stops, riders typically apply front brake with a high application force.
ABS bike experienced different ABS cycling on the front and rear wheels, which caused difficulty in maintaining lateral stability in the lane
Conclusions – LBS Considerations
No unsettling characteristics found with LBS bike. LBS used only with hydraulic brake system at both front and rear. Many bikes have hybrid brake system with hydraulic actuation on front wheel and cable actuation on rear wheel
Recommendations
Consider ABS requirements for front wheel only. Evaluate additional ABS-equipped bikes for braking in a curve performance. Evaluate ABS on rough road surface. Perform additional testing to evaluate effectiveness of burnish procedure. Develop test specifically for LBS
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