Mark This type of question has been asked on many occasions in the past. It does depend on the actual activities and how hazardous they are. That said, if people are taking part freely as a social/sports activity, then there is no need to go overboard with safety controls. Sensible precaution should be adopted as opposed to a formal risk assessment process. For example, is there a first aider to hand and first aid box? Is equipment suitable and sufficient? Do those involved know who to report to in case there was serious incident? Are intended traffic routes suitable for cycle riding at that time of day? The aforementioned controls are obviously not exhaustive, just typical examples of what you need to consider. The most important aspect is that people are allowed to enjoy themselves. Yes, duty holders (employers) have responsibilities in the workplace and outside if company sponsored events. However, it should still be proportionate to the risks with sensible precautions adopted.