From: tomes@iastate.edu ()
Subject: Re: a few questions from a wanna-be owner.
Organization: Iowa State University, Ames, IA
Distribution: na
Date: Fri, 18 Dec 1992 22:18:12 GMT

In article <JET.92Dec18130804@boxer.nas.nasa.gov> jet@boxer.nas.nasa.gov (J. Eric Townsend) writes:
>Do you mean old-style earles forks, or the newer RADD-type suspensions
>that only exist on about 3 different bikes (Bimoto Tesi, the new
>Yamaha bike, Britten's V-twin racer)?
I think that the Britten used a setup that had a wheel carrier that was 
fastened to two a-arms that were both above the top of the wheel.  The carrier
looked like normal forks except that it was a carbon fiber and was flat on the
sides, not round like fork tubes.  The whole works was not detailed in the
two magazine articles about it that I have read, because he (Britten) was still
tight-lipped about it.  The geometry was reminiscent of a drawing I saw not too
long ago of a BMW swingarm front end for their new boxer sportbike.

like this:

 
__________
pivot---> |______\<-----pivot - these two are ball joints that allow steering
	  |	  \              movement
pivot---> |________\<---pivot __ /
	  |	    \
	  |          \----
	  |	    / \   \      the rest of the "fork" assembly is rigid, with
----------	   /   \   \     some kind of scissors joint/sliding coupler to
		   \	   /     connect with the "top triple clamp" for
		    \     /      steering input at the top
		     -----

The RADD design trademark is center-hub steering, something the Tesi and the 
new GTS1000A have, but no other production bike has had, to my knowledge.  This
means that the lower swingarm is joined to the hub carrier at the axle level
of the hub carrier, and the upper swingarm is above the wheel and connected 
to the hub carrier by a strange looking peice of metal that locates the wheel
in the roll axis and allows steering input.  The RADD design uses a sliding
coupler, I think, but the Tesi uses a bellcrank-looking setup.  Could be wrong
on the Tesi.  (any BiMota type out there?)

The probable reasons for not having more bikes with differing front end designs
are engineering conservatism (if it ain't broke don't fix it: teleforks worked
well until chassis stiffness and cornering/braking forces overwhelmed them in 
the early 80's, after 30 years of development on them) and product liability.
Corporate lawyers suck, and I'll bet they had more than a little to do with the
lack of radical design changes than anyone realizes.  Turbos?  Movable
controls for setting the proper ergonomics for the rider?  Fully automatic
damping adjustment?  Rotary engines?  In other areas, better helmets and
riding gear are most often mentioned when talking about apparent lack of
progress in technology.  

I keep having dreams about a riding suit that has an
integrated head/neck system, with sound suppression built in, two way radio,
a display projected on the faceshield for FLIR/low light and pertinent data,
and material that is similar to thick lycra until a high load/acceleration 
occurs, then it acts like a viscous damping material.  Things like a climate
control system and high abrasion resistance go without saying.

Strange rantings from a finals-fried out of practice student.

CP Tomes
"Was that a truck?"
"No, it was your test....."
crunch, screech, pieces of CP everywhere