"The Medway Handyman" wrote
On 04/05/2015 20:37, Rob Morley wrote:

You do realise
they're only rated to withstand the impact of toppling off a stationary
bike, and have been implicated in neck and rotational brain injuries?

A stationary bike traveling at 14 mph?

If you're standing up, hammering something at head height and you drop the
hammer, what is the hammer's vertical speed when it hits your foot? Answer
13mph.

It is assumed that the head of someone falling off a bike can hit the ground
with similar vertical speed because it travels a similar vertical distance.
Horizontal speed (bicycle speed) does not alter the vertical impact speed.