The Right Motorcycle Helmet End Motor GpRule number one when buying a motorcycle helmet is never buy a second hand helmet. There a few very good reasons for this. Most importantly you can never be one hundred percent certain of it's history. It may look clean shiny and new but serious structural damage is often not visible to the eye. As you wear your properly fitting helmet it gradually moulds to the shape of your head to ensure a perfect fit for you. A second hand helmet will have moulded to somebody else's head.