Few, if any, formal studies have addressed safety differences between smaller mini or "pocket" bikes and four-wheeled quads. However, research suggests that two-wheeled bikes are generally safer than quads. Quad riders are up to 50 percent more likely to die in crashes than those riding two-wheeled motorcycles.
In addition to the higher overall death rate of quad riders as compared to riders of two-wheeled off-road motorcycles in accidents, a 2010 Johns Hopkins analysis found that quad riders were 55 percent more likely to be placed in intensive care after an accident and 42 percent more likely to be placed on a ventilator. It is not clear whether fatalities and serious injury trends among smaller gas-powered motorbikes are comparable to those observed from larger vehicles, partially due to a lack of formal data regarding injuries from smaller motorcycles. However, many of the mechanisms proposed by researchers to explain this discrepancy are likely to be applicable regardless of the size of the vehicle involved.
While no specific factor has definitively explained the additional dangers associated with quads, researchers have posited that an inflated perception of safety may lead quad riders to undertake riskier riding activities. In particular, quad riders tend to wear less protective gear than bike riders. Quad-related injuries still tend to be worse than bike-related injuries even if the riders wore protective gear, leading researchers to further speculate that the additional weight of quads may exacerbate injuries if the vehicle lands on the rider's head, body or limbs during an accident.