realskiers

I'm not sure of your relative numbers. In any given year, I think there are a lot more kids in various football programs around here (from Pop Warner spring and fall leagues all the way through high school) than there are adult active bike riders.
And that is in an area of the country where I think there is a high percentage of bike riders.
So if the measure is just ER visits per year, then I think the numbers of participants are at least equal, if not skewed in favor of more football players.
Offsetting this is the fact that most kids also ride a bike some, I don't know how that affects the statistics.


A different approach would be to ask 1000 people that played high school football if they had an ER visit, and 1000 active road bike riders the same question. I think the road bikers would have more, but they participate over a much longer period.
FWIW, my only ER visits have been while biking (and from getting hit in the head with a baseball bat back in 7th grade).