A shock absorber assembly comprises two springs 11, 12 arranged in series so as, in use, to extend between a pair of spaced apart spring seats. A coupling member 13 is arranged between the adjacent ends 11b, 12a of the springs 11, 12. The coupling member 13 is adjustable and is formed by a shaft having a pair of flanges 14, 15 provided on the outer surface thereof. The shaft extends axially beyond each flange 14, 15 so as to extend inside the windings of the abutting spring ends 11b, 12a to locate the spring ends 11b, 12a on the coupler 13. Each flange 14, 15 engages an associated adjacent ends 11b, 12a of one of the springs 11, 12. At least one of said flanges 14, 15 is moveable longitudinally along the shaft so as to vary the longitudinal separation between the two flanges 14, 15 and thereby vary the preload on the springs 11, 12.