I'd hate to be accused of defending Jobst, but that was my reaction as well, until I went back and reread the Jobst quote. He didn't say that the 73 degree head angle was chosen after a statistical analysis, that would be absurd. I doubt most of those who had a part in this design could even spell statistical analysis. Like most aspects of bicycle geometry, the 73 degree head angle was a result of mechanical evolution. I think what Jobst is saying is that, if you do a statistical analysis (which a framebuilder does informally, without knowing that's what he is doing, when he makes design decisions based on the experience gained through feedback from those who are riding his frames), you realize that there is good reason for the choice of that particular front-end geometry--it works under real-world conditions. Since the manuverability of the bike is controlled by the trail, not the rake, this can be designed after the head angle is determined.
Steve Barner, Bolton, Vermont
> Date: Thu, 25 Dec 2003 13:47:11 -0500
> From: Joe Bender-Zanoni <joebz@optonline.net>
> To: classicrendezvous@bikelist.org
> Subject: Re: [CR]The shape of fork bends in the old days
>
> Jobst Brandt's head angle based on road shock angle analysis seems dubious
> to me. Anyone know of further support for this theory?
>
> I have never seen an analysis of bicycle head angles, or heard of a
bicycle
> designer, starting with a statistical distribution of bumps or in fact use
> the criterion of optimizing axial bump loading to determine head angle.
>
> Everything I have seen says the head angle derives from physical layout
and
> handling/stability considerations. An example would be "Bicycling
Science"
> by Whitt and Wilson.
>
> Joe Bender-Zanoni
> Great Notch, NJ