Sorry, don't mean to be patronizing. You may know that risk can qualitatively be thought of as a product of two factors: the severity of the outcome and the pr

Sorry, don't mean to be patronizing. You may know that risk can qualitatively be thought of as a product of two factors: the severity of the outcome and the probability of occurrence. In the case of cycling a high-speed rear collision with a car is very unlikely but very severe in its outcome. How common is this accident? Not very common-- it ends up on the news when it does occur. Many many cyclists enjoy riding, on the street, for their whole lives and never have a serious accident or injury.