Bicycle safety is the use of practices designed to reduce risk associated with cycling. Some of this subject matter is hotly debated: for example, the discussions as to whether bicycle helmets or cyclepaths really deliver improved safety. The merits of obeying the rules of the road including the use of bicycle lighting at night are less controversial.

The first recorded bicycle accident is probably a collision in 1842, reportedly between Kirkpatrick McMillan, an early rider of the velocipede, and a young girl in Glasgow. The report, however, is vague and the identification disputed.^{[citation needed]}

Causes of crashes vary according to local conditions. A study conducted in 2000 by the 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.^{[citation needed]} Many bicycle crashes are unreported and therefore not included in official statistics. Prospective studies estimate that less than 10% of bicycle accidents are officially reported.