On Oct 8, 10:23*am, Jay Beattie wrote:

Sort of OT, but I was descending a familiar hill and slid out and
crashed and broke a few ribs but no major bones. *A week or so later I
felt good enough to go riding, and while descending yet another hill,
I developed a huge shimmy -- so bad, I had trouble steering he bike to
a stop. *This was on a bike that had never had a shimmy and on a hill
I had ridden hundreds of times. *It was all due to nerves.

That's really interesting. It seems very likely that a person's
shaking or trembling from nervousness would be within range of a
bike's resonant frequency for lateral vibration. Talk about a
feedback loop! Nervousness inducing shimmy, shimmy inducing more
nervousness...

Apart from
your physical rehab, it takes a little while to get over the
psychological effect of crashing. *I'm doing a lot of riding with a
guy who was hit by a car in an intersection in spring, and apart from
recovering from having his clavicle resected, he is nervous around
cars now -- particularly at intersections. *He has a tendency to jam
on his brakes at odd moments, making drafting a little challenging.

Fear can be terrible. One of my good friends experienced a near crash
on a long, fast downhill. As he told it (I wasn't there), his front
tire blew out but stayed on the rim. He panicked and locked up his
rear, which also blew out. He skidded across the oncoming lane and
stopped upright on the shoulder. No crash, but he never recovered
psychologically. Afterwards he was unable to descend at more than
about 10 mph; he was literally slower downhill than uphill. He gave
up riding soon after.

But that brings up another feedback loop. I recall from my mountain
biking days that there were obstacles I'd try to "clean" (in the
observed trials sense) that were impossible unless I committed to
taking the risk of a fall. I think a more cautious person couldn't
pull it off at all, and the failure to pull it off would lead to more
nervousness.

I can envision that phenomenon working in lots of different
situations, everything from giving a speech to controlling a narrow
lane.

- Frank Krygowski