Current New Zealand law requires that motorcyclists with a learner or restricted licence ride a motorcycle with an engine capacity of 250cc or less. Previous research has reported inconsistent findings for the relationship between cubic capacity and risk of a crash. The authors sought to determine: 1) compliance with the law, 2) if the risk of an injury crash is increased for learner/restricted licence holders who do not comply with the cubic capacity regulations, 3) whether the risk of an injury crash increases with increasing capacity of the motorcycle. A population-based case-control study was conducted in the Auckland region over a three year period from Feb 1993. Among the controls, 66 percent were riding motorcycles with a capacity greater than 250 cc. Usage rates for those with fun licence, learner/restricted licence, and no licence were 82 percent, 29 percent, and 60 percent respectively. There was no evidence that learner and restricted licence holders who did not comply with the cubic capacity requirement were at increased risk. Relative to motorcycles of less than 250cc the adjusted risk of an injury crash was elevated for all cc categories. There was, however, no consistent pattern of increasing risk as cubic capacity increased. An analysis of risk in terms of power to weight ratio and style of motorcycle may provide a more useful insight into the benefits of motorcycle design restrictions for novice riders. (A)
Abstract