July 31, 2010 by Chris Atkins
There is absolutely nothing more exhilarating than an open road on a bright summer morning, right hand settled on the throttle and no timelines to meet. What’s the destination? It doesn’t really matter when you’re on a motorcycle. The ride is the destination. Exciting and relaxing at the same time, there is a temptation to simply lay back and take in the scenery. However, when you’re on two wheels things can go very wrong, very quickly.
There are a significant number of hazards unique to motorcyclists. These are ever-present dangers discussed in rider courses, but ultimately it is experience (and inevitable close-calls) that creates rider preparedness. Challenges while riding are presented in changing road conditions, driver behaviours and vehicle interactions. Further, the suitability of a motorcyclist’s reaction to these situations is controlled by the individual’s overall handling of the bike itself.
Unexpected changes in road conditions can put a rider down. Inadequate traction and unexpected handling or response of the motorcycle can create a hazardous situation. For example, an unexpected impact from riding over a pothole can jar a rider’s hands from the handlebars. Depending on the depth and severity of the pothole, combined with the speed of the motorcycle, a pothole impact could have an effect on the weight distribution of the rider.
Roadway cracking and tar strip repairs, particularly those that run parallel to the direction of travel, tend to lead the front wheel of a motorcycle away from the intended path. Similarly, initial surface preparation for asphalt on highways involves grooving the roadway. This can continue for several kilometers and presents a challenge for riders at highway speeds. The front wheel tends to wander the roadway and constant correction is required.
Road surface sand and gravel make cornering quite hazardous. Sand and gravel acts as an intermediate layer between the motorcycle’s tires and the roadway. This can induce slippage and loss of traction. Gravel tends to roll while cornering on it and even a few unseen pieces can cause either the rear or front tire to slide out.
Ideally, every motorcycle trip is 25 degrees with not a cloud in the sky. However, drivers ride in all sorts of weather and motorcycle tires are very sensitive to temperature. Taking a simple right hand corner at typical operating speeds just after the motorcycle has been warmed up in 10 degree weather can put a bike down. The coefficient of friction needs to be at a critical rate to support the traction required to complete a given maneuver. This coefficient changes (increases) with higher temperatures. At lower temperatures tires may not possess the necessary coefficient of friction to brake and turn as the rider requires. As the bike is ridden, frictional forces induced by the roadway-to-tire interaction increase the tire temperature and coefficient of friction.
Similar to low temperature, wet weather can drastically reduce available traction. This is most common during the first few minutes of a downpour when the moisture washes any present oil, coolant, etc. onto the roadway creating a particularly slippery condition. Painted lane markers, sewer grates and train tracks are also areas that can provide virtually no traction when wet.
No matter how competent the rider or how much experience he or she possesses there is always the presence of uncontrollable variables in other drivers. Drivers making a left hand turn in front of a motorcyclist present a particular challenge. A driver’s perception of how far the motorcycle is and at what rate it is travelling can be difficult. A driver’s perception of another vehicle’s speed is based on the typical width of a vehicle and how that vehicle width is changing — increasing in size as it approaches. However, this leaves room for error, as a motorcycle’s width is much smaller than that of a typical vehicle, which can affect the left-hand turning driver’s perception. This is further exacerbated by the fact that motorcycles represent only a small fraction of vehicles on the roadway and tend to be present seasonally. Therefore drivers have not acquired the same skills for judging closing speeds with motorcycles as they have with other types of vehicles.
Motorcycle conspicuity is also an issue to consider. Factors such as road-related hardware (stop signs, utility poles, etc.) other vehicles in the traffic stream, weather conditions, time of day and blind spots can have a significant effect on how well a motorcyclist is seen by drivers on the roadway.
In the city, taxicabs are also very hazardous because a taxi parked at the curb can suddenly merge into the lane or make a u-turn in front of the motorcyclist.
Due to the small size of a motorcycle it is difficult, at times, to protect space. Drivers tend to follow too closely and often times intrude into the motorcyclist’s lane. To protect their lane, riders need to position themselves in the tire track adjacent to the traffic beside them. In addition to protecting his or her lane and space, a rider in this position can avoid motor oil and surface undulations, which are more likely in the middle of each lane.
With all the hazards present on the road, limited experience with a motorcycle can be the most hazardous. According to the Hurt Report1 “motorcycle rider error, such as slide outs and falls due to over braking or running wide on a curve due to excess speed or under-cornering account for two-thirds of the single vehicle accident cases.”
A driver stomping on the pedal of a vehicle with ABS braking requires much less skill than a motorcyclist who has to coordinate both a front caliper (right hand lever) and rear caliper (right foot lever) while applying the suitable ratio of force to each.
In a panic situation, the average car driver would likely respond by pressing the brake pedal suddenly and as hard as they could. Depending on the speed and traction available locking the front brakes of a motorcycle can ‘lowside’ the motorcycle almost instantly, or propel the rider forward off of the bike. Motorcycle ABS systems are relatively new, and only a select few models are becoming available.
Counter steering and leaning into a turn are other skills unique to motorcycle riders. Counter steering involves turning the motorcycle’s handlebars in the opposite direction of the actual turn. This maneuver is confusing especially for newer riders because the amount of counter steering required to get the bike to lean is quite minimal.
Experience provides a database in a rider’s mind for situations that may be present around each corner. Even for the most experienced riders, new unexpected challenges still exist.
Understanding the various elements involved in motorcycling is a critical factor in understanding motorcycle claims. See you on the road, and keep the shiny side up and the rubber on the ground.
Chris Atkins of Walters Forensic Engineering Inc. can be seen cruising on his Ducati Sport Classic GT1000 north of Toronto’s busy streets and commuting within the city.
1. Dr. Hugh H. Hurt, PhD. (January 1981 (Final Report), Motorcycle Accident Cause Factors and Identification of Countermeasures, Volume 1: Technical report, Hurt, H.H., Ouellet, J.V. and Thom, D.R., Traffic Safety Center, University of Southern California, Los Angeles, California 90007, contract No. DOT HS-5-01160, U.S. Department of Transportation, NHTSA, http://www.ct.gov/dot/LIB/dot/Documents/dhighwaysafety/CTDOT_Hurt.pdf