The F1 champion is determined over the course of a season. It is also fair to say that the driver is heavily dependent on the car they are driving. The dependence of the man on the machine is less in cycling. Therefore, I wondered if the age of cycling champions is declining. I looked at the UCI World Championship Road Race for the same 1950-2015 period. It is a far from perfect comparison as it is a one-day race. However, it does have the "advantage" of being more a race of individuals than any of the grand tours (although one could argue that there are national teams and tactics). Here is the age of cycling world champions. The same colour coding applies to the circles.
Below is a direct comparison of the F1 and Cycling World Champions ages for the period. I'd be slow to say there is any firm conclusions.