Roadster wrote:Wider and hence heavier tyres will make the bike less wobbly because they add mass to the rotating rims of the wheels: this increases their gyroscopic effect which keeps the bike upright when moving forward.
However, the effect increases with speed and doesn't really help stability until bike and rider are reasonably underway. After that, even the narrowest and lightest tyres will have significant gyroscopic effect, so you might choose wider, heavier tyres for other reasons (like comfort) but not merely for the sake of improved stability.
Studies have shown that even in "bicycles" where the gyroscopic effect of the (front) wheel is cancelled out mechanically by a contra-rotating wheel (see http://science.sciencemag.org/content/332/6027/339?sid=c68a2457-3d07-4a97-9912-b8a73ab69376 amongst others) the bicycle is self-stable when pushed and released, so I wonder in what context the gyroscopic effect might be considered "significant"...?
I repeat, neither the gyroscopic effect of a wheel weighing a few pounds, or the self-stability of a bicycle weighing a few tens of pounds, will balance a rider weighing several stones.