Spring constant (k) represents how stiff the spring is.		Shock leverage ratio.
	k.total - use to compute race sag		TR - (wheel travel / shaft travel) . . fixed or static measurement
	k.increm - the change in spr rate for small changes in stroke position		Used to compute race sag
	- use to look for closing coil effect on spring rate increases		LR - the change in rate for small changes in stroke position . . incremental or instantaneous