Causes of crashes vary according to local conditions. A study conducted in 2000 by SWOV (Institute for Road Safety Research) in the Netherlands found that single bicycle accidents accounted for 47% of all bicycle accidents, collisions with obstacles and animals accounted for 12%, and collisions with other road users accounted for 40% (with the remaining 1% having unknown or unclassified cause).
... it is clear that motorists hold negative views about cyclists and tend to view cycle users as an ‘out group’ with significantly different characteristics from most road users ... the ‘out group’ status of cyclists brings with it a tendency among drivers to impute the poor or incompetent behaviour of some cyclists to all cyclists.
...the effect of infrastructure that clearly defines ownership of space, in the case of these experiments the provision of cycle lanes in the virtual reality worlds, appears to increase driver confidence and, hence, potentially risky behaviour, such as higher vehicle speeds and less speed reduction when encountering cyclists..
This is what one would expect; a cyclist only accident only provides a small amount of kinetic energy due to relatively small mass and low speeds, whereas a motor vehicle can provide more. Falling off and hitting obstructions tend to be relatively minor, seldom requring medical attention, hence sparsely represented in statistics.
As long ago as the early 1930s there were efforts to clear cyclists off the roads to make way for private cars, then largely a preserve of the elite. These were successful in Germany, then an authoritarian regime, and spread during the war to German-occupied countries such as the Netherlands where civilian motor transport was also crippled by fuel rationing, but was resisted in other countries.
During the mid-part of the twentieth century, the traffic engineering response to the increased use of motor vehicles in the United Kingdom, as in the rest of the industrialised world, was to look for solutions which not only eased the passage of traffic through the streets, but which also protected vulnerable road users from the dangers of the motor car. In the 1940s, an influential proponent of this ideology was Herbert Alker Tripp, an assistant commissioner of London's Metropolitan Police. Tripp argued in his book Town Planning and Road Traffic that: "If we could segregate pedestrians completely from the wheeled traffic, we could of course abolish pedestrian casualties". This philosophy was also pursued by Colin Buchanan, his 1963 report for the UK Government Traffic in Towns, defined future government policy until the end of the century. Buchanan himself knew that segregation had not been proven to work in the case of cyclists, he famously wrote in his 1958 book Mixed Blessing "The meagre efforts made to separate cyclists from motor traffic have failed, tracks are inadequate, the problem of treating them at junctions and intersections is completely unsolved, and the attitude of the cyclists themselves to these admittedly unsatisfactory tracks has not been as helpful as it might have been".
Most important among these is the understanding of road position.