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by uoaei 3086 days ago
Kinetic energy = 1/2 m v^2

In a typical city scenario, a car has KE of 1/2 (2000 kg) (50 kph)^2 ~= 2e5 Joules. A bicyclist has 1/2 (100 kg) (30 kph)^2 ~= 3.5e3 Joules. Almost 100x less capable of inflicting damage on a typical pedestrian. Add onto this that bikes are way more maneuverable, less collision surface area, are totally exposed to the same forces exerted on the pedestrian with which they may collide... your comparison with cars is intellectually dishonest because you are comparing a human on top of a 10-20kg machine with a human inside a 2000kg metal box with an incredible array of safety features for the driver and hardly any for pedestrians outside.

1 comments

Also, 30 kph is practically the top speed for a majority of cyclists - there's a level, narrow, short (200 m), 30-max-speed, all-traffic (except pedestrians) tunnel on my usual route. Do I temporarily reach 30 kph there, in order to be polite and get out of there as fast as possible? Yes, with some difficulty. (Do drivers honk at me for being unbearably slow while going the max legal speed? Yes.)

So, I'd say a typical city scenario is <20 kph, more than halving the estimate.