Possible to ride bike with steerer welded straight ?

[Yellow Saddle]

This looks like something I pull out of the plug hole after a bath...

Naah, I don't see any false teeth in there.

 

[winjim]

That diagram is quite pretty but I suspect the speeds involved were quite low. I baled out halfway down a long hill at about 25mph when the bike went into a violent shimmy. The bike instantly stopped shimmying and carried on quite happily to the bottom of the hill, about 200 yards, until it rubbed on the grass verge and stopped upright (that last bit was just a stroke of luck - if the left pedal had been down it would have dug in and flipped).

This was before I rode with clipless pedals. When I was at school, we would practise jumping off bikes at low speeds on grass - it's easier than you might think if you're not attached to the pedals. You can try to land on your feet or go for a parachutist's roll.

It's a simulation, by somebody trying to teach an AI how to ride a bike. Their results suggest that speed is not important although to get a pretty pattern like the one in the diagram, initial velocity (ie speed and direction) would need to be constant.

Interestingly, when they optimised the AI for speed, it rode in fast swooping motions. When they optimised for a straight line it fell off immediately as it didn't want to turn the bars. When they optimised for staying upright it started doing stunts. They also point out that for a human cyclist, riding a computer simulation is really difficult as direction is controlled by lean and countersteer so it's not intuitive at all.

Search 'It takes two neurons to ride a bicycle' to find the paper.