[MENTION=392672]Tiglath[/MENTION], the numbers you provided are not really meaningful with respect to risk without knowing the amount of participation in each sport. For example, estimated one million boys play football in high school, while about 14.5 million kids 7-17 ride bikes. (Census Bureau and National Sporting Goods Association Sports Participation Study,2010 & 2000).

So the fact that there are more head injuries in cycling than in football does not mean that cycling is more risky. It's the other way around, by a great margin. Further, that is only approximate since you really need to compare the time spent in each activity instead of just persons, and you may find an even greater discrepancy (in favor of cycling being safer).