Motorcycles are highly sensitive to changes in roadway conditions. Potholes can destabilize a motorcycle, causing the rider to lose control. The following is a case in which a rider claimed he was traveling at only 15 miles per hour, when he came upon a large pothole in the roadway and lost control. The motorcycle fell to the right, with the right foot peg penetrating the rider’s leg, leading to a near amputation of his right foot. Dr. Lloyd was retained to investigate the cause of the motorcycle pothole crash.

Test Instrumentation

An exemplar Honda CBR 929RR motorcycle was acquired and instrumented with accelerometers installed on the front axle, rear axle and handlebars:

Data acquisition was controlled using a National Instruments cDAQ 9178 and acquired at 10 kHz per channel on a Windows tablet running LabVIEW software:

Pothole Crash Testing

Using the instrumented motorcycle, Dr. Lloyd constructed an exemplar pothole in an open parking lot using ramps to investigate how the length and depth of the pothole affected stability of the motorcycle. In addition to sensors, testing was recorded using high speed and standard video, as well as GoPro cameras mounted on the motorcycle

Results

Based on analyses and physical evidence, that the speed of the motorcycle while crossing the roadway defect was likely 14 -18 miles per hour. At such speeds, the front and rear suspensions have a tendency to approach maximum compression. along with substantial deformation of the tires.

Conclusions

Dr. Lloyd determined that the motorcycle crash was caused due to the motorcycle accelerating as it crossed the pothole. When the rear wheel crossed the fore edge of the defect it lost contact with the roadway and the rear wheel speed increased without resistance. Upon contact with the aft edge of the roadway defect the rear wheel was at a higher rate of speed than the rest of the motorcycle, causing the motorcycle to unexpectedly wheelie.

Please call Dr. Lloyd at 813-624-8986 or email DrJohnLloyd@Tampabay.RR.com to discuss how he can be of help to you with your case.