The microstrip silicon tracker of the CMS experiment will operate in a 4 T magnetic field in the harsh radiation environment of the Large Hadron Collider. The drift motion of the charge carriers will be therefore affected by the Lorentz force due to the high magnetic field. Furthermore, radiation damage will change in time the properties of this drift. In this note a method to measure the Lorentz angle from reconstructed tracks is presented and results obtained on Magnet Test and Cosmic Challenge data are compared to the values expected from a model, developed by the authors, which takes into account all the relevant parameters during the tracker lifetime (e.g. temperature and depletion voltage of the detectors)
