Comment by mmooss
6 hours ago
> The bike may have a lot less mass but it also has a lot less traction
I've long wondered about that tradeoff: I've heard some (non-physics-aware) people say that heavier cars/trucks stop faster because they have more traction, but obviously there's a big tradeoff in that equation. As a guess, on a moving wheeled vehicle, 1 kg adds forward energy proportional to velocity, and downward energy constant and independent of velocity? And maximizing that tradeoff would seem to be an engineering goal in order to minimize muscle/gas expenditure. (I'm sure it's well-known but I'm too lazy to look up the details.)
That ignores road/tire and air resistance which are proportional to velocity. And I suppose a key question is the degree to which traction depends on vehicle weight: maybe it depends more on tire and road characteristics, for example. Certainly ice or some kind of low-grip tire would be a big factor.
And that ignores locking up the wheel, as you pointed out.
You could just get on a bike and test for yourself your theory. People who ride bikes tell you they are not good at stopping quickly, perhaps you should ask yourself how you became so knowledgeable without riding?