never

it's all to do with speed divided by boredom multiplied by frequency of vehicular vibrations. basically when a certain pitch is reached two things tend to happen, firstly a stiffy ensues and secondly (when driving in the desert) a series of ruts occurs at right angles to the direction of travel causing the vibration. military boffins did a sum.

Posted By: Tombs, Sep 20, 17:09:56