Rear wheel lockup

 

Why does the rear wheel come around sideways when locked up?

Maybe I'm just dense, but I've read/heard several explanations and still
don't really understand why this occurs.

Thanks,

Bart

 



IF the rear wheel were to lock up when it was moving
in a direction precisely aligned with the bike's centerline
and direction of travel - meaning that there is precisely
zero net force to one side or the other at the contact
patch - it wouldn't.  But how often does that happen?

When a wheel locks up, the traction goes WAY down.
It's the difference between "static friction" and "kinetic
friction" - the latter being the force due to friction as
seen in two surfaces sliding over each other.  Kinetic
friction is almost always way less than the static case.
Loads to either side which were insufficient to move
the wheel out in the static case become more than
sufficient once the wheel starts sliding and overall
friction/traction goes down - and hence the thing moves
to whichever side the force dictates.  There being a
pivot between the rear and front wheel, the bike is
more than happy to let it if nothing else happens to
correct this condition.

Bob M.

 



By how much, actually? 30%? 60% 99%?


Yep. (In high school and college, we called it dynamic friction, not
kinetic, but that term will work, too.)

--
Timberwoof <me at timberwoof dot com>
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On a dry road, mu goes down from around 1.0 to around 0.6 - so about a
third, roughly.

cu
  .\arc

 

 marc.gerges@gmail.com (Marc Gerges) wrote:


Thanks. That's "significant", but is it "WAY"? :-)

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faq:  http://www.timberwoof.com/motorcycle/faq.shtml