I recently had an argument with someone on why a bicycle with a broader steer gives you more control. We both had different answers to this question and neither could convince the other.
First a schematic drawing of the situation:
Both claims assume that the only force on Body is gravity, denoted $F_g(Body)$. This force is carried on through the bicycle to where the wheel touches the floor. The bicycle is assumed to have no mass.
Now the two claims:
Your body and both hands form a triangle. This means that the force $F_g(Body)$ is split up in horizontal component vectors and vertical component vectors. The claim is that this by this, not all of $F_g(Body)$ is directed downwards anymore. So the force acting on the floor through the wheel would be less than $F_g(Body)$. If the steer is broader, the horizontal components will increase in size and thus the vertical components will decrease in size. Meaning that you wouldn't press down on the floor as hard with a broader steer resulting in less friction=less control.
The steer would provide a counter force for the horizontal components.
When you're steering, the bicycle is leaning. So the point where the wheel is touching the floor could then be considered a fulcrum. A broader steer would mean a greater distance to the fulcrum, thus a bigger moment. This would be harder to compensate=less control.
My question now is: "Why do you have less control over you bicycle when the steer is broader. I would like to know the correct physical explanation and what is wrong with the claims (or perhaps somethings wrong with our assumptions)."
N.B. I am not a physicist myself (I'm a mathematician), so forgive if I made some obvious mistakes.