We present experimental data on the bandstructure and high mobility transport properties of 6H and 4H-SiC epitaxial films based on optically detected cyclotron resonance investigations. From the orientational dependence of the electron effective mass in 6H-SiC we obtain direct evidence for the camels back nature of the conduction band between the M- and L-points. The broadening of the resonance signal in 4H-SiC as a function of temperature is used to extract information on electron mobilities and to conclude on the role of the different scattering mechanisms.