The inventive device for measuring forces, in particular radial forces produced on an axis or another piece, for example on the axis of the rear wheel of a motorcycle. Said device comprises a measuring sleeve (1) arranged around an axis (3) in such a way that a force to be measured is produced thereon by means of said sleeve. Said device also comprises a strain gauge (40) which makes it possible to determine the deformation amplitude of the part of the measuring sleeve in order to deduct the amplitude of the produced force. The invention can be used for measuring the tensile stress of a motorcycle chain.