According to the largest risk consultation firm in the US[i] and a noted Australian statistician[ii], this is the rank of these activities, in fatalities per million hours:
#1 = Small planes:
15.6 fatalities per million hours;
#2 = On-road
#3 = Swimming, 1.07;
#4 = Walking near
#5 = Bicycling, 0.26
to 0.41 fatalities per million hours
In other words,
cycling is the safest of all of these activities, on a per-hour basis.
By the way, just "living" comes out to 1.53
fatalities per million hours. It
seems that cycling is, on average, much safer than many other things you might
do with your time!
[ii]. Robinson, D.L., Head Injuries and Bicycle Helmet Laws, Accident Analysis and Prevention, vol. 28, No. 4, pp. 463-475, 1996