Seems to me that a major problem is that quad bikes have become on the average too big, heavy, complicated and expensive -including for fuel used. . My father was one of the early purchasers of a 3 wheeler for farm use in late 1972, not long after they first appeared. Motor was basically that of Honda 90 cc postie bike. Unfortunately 3 wheelers were discontinued, apparently because they were banned or restricted from use in snow in USA because too many idiots were killing or injuring themselves from tipping three wheelers over. 4 wheelers are inherently more stable but due to the large amount of power many current ones have, riders are more inclined to get themselves into trouble. Then effects of accidents, especially rollovers are often more severe than for smaller bikes, etc because these 4 wheelers are so heavy. Note a neighbour of mine recently updated to a new large 4 wheeler. It has uses that nothing else can do on an irrigation farm. However, he doesn't mind reminding everyone that it uses more fuel for distance covered than a Nissan Patrol he has. Seems to me that the independent suspension, which is good when near new may be a "can of worms" as components wear and/or bend.
