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Re: As the wheel turns

To: "MG List" <mgs@autox.team.net>,
Subject: Re: As the wheel turns
From: "Larry Daniels" <ladaniels@sbcglobal.net>
Date: Fri, 3 Jun 2005 17:20:58 -0500
----- Original Message ----- 
From: "David Lieb" <dbl@chicagolandmgclub.com>
Subject: Re: As the wheel turns


> If anyone else is willing to duplicate this ...

All I know is that bicycle speedometers want you to mark where the wheel
touches the ground on both the wheel and the ground, roll it forward with
your weight on the bike until the mark touches the ground again, mark it and
measure between the marks. Talk about begging the question!

******************************

Something Paul Tegler said helped me figure out why the loaded circumference 
of the tire does not correspond to the distance the tire rolls in one 
revolution.

Say, for example, you have an unloaded tire with a circumference of 80 
inches and, when the tire is squashed by putting the weight of the car on 
it, the contact patch takes up a length of the unloaded tire's circumference 
of 8 inches -- or 1/10th of the total circumference.  Now, since the 8 inch 
arc of the tire is now in a flat, straight line where it contacts the 
ground, it takes up less distance -- the shortest distance between two 
points is a straight line not an arc.  If that flat contact patch is now 
only 7 inches long rather than the 8 inches of arc when unloaded, then the 
sum of the 10 contact patches going around the tire is 10 times 7 inches or 
70 inches.  So the 80 inch circumference tire in this example will travel 70 
inches in one revolution.

Larry Daniels
79 MGB LE
72 Midget
58 Bugeye

"You only need two tools: WD-40 and Duct Tape. If it
doesn't move and should, use the WD-40. If it
shouldn't move and does, use the duct tape."




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