[ExI] A Gedanken Bike Experiment

Kelly Anderson kellycoinguy at gmail.com
Tue Oct 29 17:17:50 UTC 2013

On Tue, Oct 29, 2013 at 8:11 AM, spike <spike66 at att.net> wrote:

> ** **
> ** **
> *From:* extropy-chat-bounces at lists.extropy.org [mailto:
> extropy-chat-bounces at lists.extropy.org] *On Behalf Of *Anders Sandberg
> *Subject:* Re: [ExI] A Gedanken Bike Experiment**
> ** **
> Ooops apologies, I didn’t explain that very well.  The Bismuth Tin Lead
> alloy melts at about 97C, which a vulcanized tire can tolerate.  So you
> melt the stuff in a water bath, drill a small vent hole in the top of the
> tire, pour in the liquid metal until it is up to the vent hole, let the
> tire cool to room temperature, freezing the metal.  Now it is a very hard
> very heavy tire.  What I want to know is how the bike would handle.  The
> gyro action of the front wheel would be increased way more than the factor
> of 30, for the radius of gyration would be increased.  So the moment of
> inertia of the front wheel would be increased by a factor of over a 100.
> That would introduce weird handling.

The primary thing you would notice first would be that steering would be
way more difficult. As you point out, gyroscopic forces would tend to make
the wheel want to stay straight, so much more force would be required to
turn the handle bars. Fairly intelligent power steering might be able to
fix that issue.

The other thing you would likely notice is less traction. The pliability of
a normal tire gets more of the tire on the surface of the road. Take away
that flexibility, and you have less tire contacting the road, and thus
would be more of a slippery issue. Since the bike is heavier, you would
need more traction, not less to safely negotiate corners.

The third think I can think of is that the ride would be far more bumpy.
This would also lead to stability issues, particularly in cornering.
Imagine hitting a pebble, and losing almost all contact with the road for a
brief time. That could lead to a kind of skipping that would likely be very

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