Re: Wandering, Negative Steering Roll Radius?

[Phil Rose <pjrose@servtech.com>]

>Date: Thu, 4 Feb 1999 09:56:04 -0500 (EST)
>From: "Graydon D. Stuckey" <graydon@apollo.kettering.edu>
>Subject: Re: Wandering, Negative Steering Roll Radius?
>
>On Wed, 3 Feb 1999, Scott Mo. wrote:
>
>> for thought and ask does a change in wheel offset/width alter this Negative
>> Steering Roll radius enough to make the car more susceptible to wandering?
>
>Yes.  Possibly, or if you change the offset in the right direction, it
>could even get better.
>
>> NSRR places each front wheels pivot point outside the center of the tires
>> axis. This has the effect of making the front wheels want to return to
>> center-to turn in the direction opposite that of the pivoting force-even
>
>Most modern automobiles have this "feature."


Bicycles, too, have it--assuming I understand the NSRR concept in
automobile steering. With bikes it's determined by the rake angle of the
front fork plus the "offset" of the hub ("offset" there being determined by
the curved length at the end of the fork rather than any side-to-side
offset as in the automobile's wheel). The rake and offset combine to place
the bike tire's contact patch ahead (or behind) the point at which the
steering axis meets the ground); and the variations make for more (or less)
straight-ahead stability.

If I recall correctly, track bikes have little or no hub offset, so
steering response is very quick, but straight-ahead (especially "no hands")
riding is pretty difficult to maintain.


Phil Rose				Rochester, NY
'91 200q				mailto:pjrose@servtech.com
'89 100