[ST] re: another RaceTech suspension question.

[Jim Huber <jhuber@xxxxxxxxxxx>]

>  From: John Hickman <jhickman@xxxxxxxxxxxxxx>, on 04/24/2001 09:14:
>  I am not very suspension savvy, so correct me if I'm wrong.  It it my
>  understanding that the emulator setting choice (and to a lesser extent the
>  oil wt) is affected only by personal riding style/preference and that the
>  spring strength choice (which has some adjustability through preload) is
>  affected by rider + cargo weight.  Is this right?
>  
>  More specifically, the oil weights and emulator turnout settings reported by
>  different posters should be independent of their respective weights, right?

	The oil weight controls damping force, assuming the size of the holes
doesn't change. Thicker oil means more damping force. Rebound damping is more
heavily affected than compression damping. The preload on the emulators
controls the point where the shim stack opens to reduce compression damping.
That's the real difference between cartridge forks and damping rod forks - two
different compression resistances, one for "small" bumps and one for "large"
bumps, with a "breakover point" between them. Damping rod forks get
exponentially firmer as bumps get "larger".
	So the practical answer is that oil weight and emulator settings are
fairly independent of bike load, mostly. Heavier springs require more damping,
and heavier loads mean you'll want heavier springs. I run 1.00 Kg/mm springs
myself, which I believe are the heaviest springs RaceTech sells. But the ST is
a heavy bike by sportbike standards, and I'm a heavy rider plus luggage. I
think the minimum spring I'd use in a Sprint ST/RS would be 0.90 Kg/mm, which
would use about the same damping. Stock springs are 0.70 Kg/mm as measured by
RaceTech, but are reported by Triumph to be dual-rate, so they should get
stiffer as they compress.

Hope this helps,

	"Jedi"  Jim

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