LOL - you are still falsely drawing a link between the risk of brain injury in a variety of sedentary activities such as showering and sleeping and that of riding an unstable two wheeled device at likely speeds of 15 - 18 mph. Theses situations bear no comparison whatsoever.

Since force is increased exponentially with increases in speed, slipping in the shower will result in a much lower risk of cerebral injury than crashing a bicycle at 18 miles an hour. In the one case, your head might strike something at 5 feet per second and in the second at 26 fps. Lets round it down and say 25 fps. Five times faster.

Using the formula F=mv2, assuming a person weight of 170 pounds, falling in the shower onto your head might result in an impact of 5fps which translates to

170x25 or 4250 (v2 being 5fps x 5 fps)

Whereas in the second case of a 17mph fall onto the head from a bike it works out rather differently:

170x625 or 106250. (v2 being 25 fps x 25 fps)

The force is 25 times as great.


Therefore, I conclude that it is entirely specious to enter sedentary activities like slipping in the shower or falling out of bed into a discussion of the advisability of wearing a cycling helmet.



Right - I am off to the pub on my bike to meet a nice lady. I will endeavour to keep my speed down to 5 fps since I am not in spite of the above going to walk into a pub looking like Mushroom Man.