An apparatus for attaching to a bicycle, the apparatus comprising a support frame including a rearward portion and a pair of spaced members extending forwardly for receiving the rear wheel and for attachment to the rear wheel axle of the bicycle. Volatile memory communicates with the DVDHDD control module and stores volatile data relating to the operation of the DVD assembly and the HDD assembly. This processing is repeated to enable a reduction in the total energy of the entire plane. A code length of the second error correcting codes is shorter than a code length of the first error correcting codes. By refracting the beams refracted from the disc at a proper refractive index, the \xb11st-order beams can be projected onto the same position, irrespective of the wavelengths.