A paradoxical thought experiment

 

Imagine an extremely lightweight (but very strong) sidecar
mounted on the right-hand side of the bike (meaning
no offence to Brits, Kiwis, Ozzies, Sri Lankans and others).

Make a hard left turn; the chair lifts because it lacks
enough weight to keep the bike from leaning into the turn.

Then make a sharp right turn. Once again it lifts because
the rig's center of mass is offset above the wheels'
contact patches (where the turning forces are applied),
creating longitudinal torque.

So the chair flies no matter which way the bike turns!
Surely I'm not the first to discover the Massless Sidecar Paradox.
Perhaps I should qualify this by saying, "Above a certain speed
the chair flies no matter what the turn."

However, it gets more even more paradoxical. The turn
(and the lean) to the left would be by counter-steering --
ie, turning right -- towards the chair! But then,
why wouldn't it just turn that way?

So -- turn the bars left. Without the chair, that would be
counter steering for a right turn. But the chair prevents
a lean to the right, so I suppose the whole rig turns left.

Then turn the bars right. That's countersteering to the left,
and with a weightless chair there's nothing to stop a lean
(and a turn) to the left.

So (above a certain speed) the machine will only turn left!!??

SQ [being intentionally dense just for the fun of it]

 


Isn't the function of a sidecar to carry a female pasenger?

I'm trying to imagine a female passenger which wouldn't negate your
entire thought experiment by weighing 110~140 pounds or so...

 


Dates Fat Chicks ladies may require additional study i.e. overall
effect.

 

sean_q_ wrote:

Well, sure.  You've described a situation which can be equally
well described by saying you have a motorcycle (all by itself, since
the mass/weight of the sidecar has been eliminated from consideration)
which is simply somehow prevented from leaning to one side, so
countersteering  cannot be employed symmetrically.  It'll lean (and steer)
normally in one direction, but not the other - so any attempt at a sharp
turn
in that "other" direction (where "sharp" is dependent on speed)
becomes an instant highside/roll/whatever-you-wanna-call-it.

So above a certain speed, it will only SUCCESSFULLY make a
quick turn one way and not the other.


Bob M.

 

Bob Myers wrote:

Which, just to reply to myself, is true of a sidecar rig anyway, to
a different extent, right?  The thing is by its very nature always
going to be asymmetrical in its handling.

Bob M.