A telescopic steering column assembly includes at least one support bearing assembly that comprises an inner bearing race which is located on the steering shaft, an outer bearing race that is located on an inner face of a shroud, and a set of ball bearings that are located between the inner bearing race and the outer bearing race and are free to roll along bearing surfaces defined by the bearing races. Each of the bearing races comprises a pair of annular bearing race parts, defining a circumferentially extending bearing surface arranged coaxially and spaced apart from each other axially such that varying the spacing between the two parts varies the effective radius of the bearing race. The support bearing assembly further comprising an inner annular support sleeve that is located between the inner bearing race and the inner shaft, an outer annular support sleeve that is located between the outer bearing race and the shroud, and a biasing means that in use applies an axially directed thrust between a first one of the annular support sleeves and one of the respective bearing race parts, and the bearing assembly is arranged such that the axial thrust applied by the biasing means is converted into a radial thrust that is applied to the inner bearing race and outer bearing race to force them into engagement with the inner and outer sleeves respectively.