I don't argue that a neutral steer criterion exists, but I doubt it's safe to assume that all frames are built following that functional relationship. At any given head angle, one may choose to design for a faster or slower steering response. It seems safer to measure head angle at the straight-ahead position, rather than to depend on a framebuilder having slavishly followed this criterion.
On Wed, Oct 7, 2009 at 4:03 AM, MMullett(BTInternet) <
mikemullett@btinternet.com> wrote:
> Ken Freeman wrote - >>Turning the bar 90 degrees causes the head tube to
> drop, steepening the head
> tube measurement.<<
>
>
>
> Every head angle has a correct fork rake. The top tube will drop only if
> the fork rake is too short for the head angle. It will also rise if the
> fork rake is too great for the head angle.
>
> The relationship for no movement is: Fork Rake = Wheel Rad (1- sin a) / cos
> a,
>
> Where a is the head angle.
>
> Seat angles for team bikes at Ilkeston were not quoted, but the dimension
> used was afterbracket or set back as Norris Lockley outlined in his post.
>
>
>
> Mike Mullett
>
> Reading UK
>
--
Ken Freeman
Ann Arbor, MI USA