Abstract: A spring member comprises an annular polymeric structure 1 interrupted by gap 3 to define annular structure ends 4 provided with attachment adaptions, external at 8 and internal at 6. Thus wheel 12 journalled at 7 in extension 6 is resiliently mounted by virtue of the elasticity of the annular structure material. Proportions, dimensions and materials can be varied over a wide range of applications. A particularly valuable application of such a C-shape spring is in the provision of a resiliently mounted castor wheel with a resiliently mounted pilot wheel giving easy passage up over a door sill or the like.