Re: rear disk brakes - Motorcycles

[Tom Mandera <tsm1@domain.elided>]

"John A. Landry" wrote:
> 
> received through the Motorcycle Safety Foundation's Experienced Rider
> Course with controlled rear wheel lock-up stops from 30+ mph was quite
> simple and executed without diffculty.  I suppose there must be some huge
> difference between a motorcycle rear wheel lock-up and an automobile rear
> wheel lock-up that I can't quite fathom at the moment.

I recall those same 30mph skids in the Safety Courses.  I was the only
one that actually hit 30mph in our class.. and I skidded right out of
the parking lot and into the next. :-)

I recall that the rear end wants to come around when you're in a rear
wheel skid on a bike just like in a car.  But on a motorcyle you're
better able to compensate by throwing your personal body weight about a
bit and "manhandling" things.. 

The issue with a front wheel lockup on a bike is you lose your lateral
stability.. the front goes this way and that, and yeah, you go down.  I
don't think the rear wheel is able to compensate for the left/right
motion like the front can be used to turn into the skid and compensate
for the rear.

A car doesn't have to worry about staying upright, so even if the front
wheels lock up, you have two skidding tires holding you up, vs.
balancing on one skiddin' tire.

Because of the weight transfer to the front tire in a brake, the rear
can flop around all it wants.. the "control" tire has lateral traction.

Of course, if you're in a turn and you panic trying to stop and/or lean,
and you over do it and dump the bike at 45mph like my mom liked to do,
down you go.. and off to the hospital with a knee skinned to the bone.. 
Coefficient of friction is no where near helping you there.. and I guess
knee caps don't have a high coefficient of friction either..

She still wouldn't let me have the Harley after that...

-Tom

Oh, and as for Dr. Landry... he even WD40'd the lug nut studs before
he'd let me put the lug nuts on the Traveler!  But.. take heed, John,
I've been WD40ing old bolts since then... wow, it *does* work better..