Neat video on the physics behind bicycle stability.

29er atmo

That girl’s bike don’t fit.

only when drunk?


really wish one of the old dudes had thrown down a natty fab in the credits

I liked that, and would like to see a deeper (but still not too technical) explanation of the paper.

Not enough detail:

Too much detail:

The gist is that there has to be some sort of interaction that couples tilting the bike to steering the bike in that direction. Positive trail does this; it isn’t the only thing that does, and it isn’t necessary. Having a mass in front of the fork’s axis, with a center of gravity lower than the frame’s, will do the same thing (make the bike steer in the direction of the lean, stabilizing it).

Here’s the relevant bit from the paper:
With no gyroscopic torque and no trail, why does our experimental TMS bicycle turn in the direction of a fall? A general bicycle is complicated, with various terms that can cause the needed coupling of leaning to steering. Only some of these terms depend on positive trail or on positive spin angular momentum in the front wheel. In the theoretical and experimental TMS designs, the front assembly mass is forward of the steering axis and lower than the rear-frame mass. When the TMS bicycle falls, the lower steering-mass would, on its own, fall faster than the higher frame-mass for the same reason that a short pencil balanced on end (an inverted pendulum) falls faster than a tall broomstick (a slower inverted pendulum). Because the frames are hinged together, the tendency for the front steering-assembly mass to fall faster causes steering in the fall direction. The importance of front assembly mass for Jones-like static torques has been noted before.

This ties in somehow with low trail/front loads, but I’m not sure exactly how. Maybe too much self correction, like you’d get with high trail and a CG in front of the steering axis, results in overcorrection and won’t allow the asymptotic decay/stabilization that you normally see.

thanks for that euclid!