397 Motor-cycle casualties IN the first five months after petrol was de-rationed, motor-cycle casualties rose alarmingly. They increased out of all pro- portion to those of other road users. What's the reason? What can be done? Study of accidents shows that, in case after case, the cause was carelessness, excessive speed, lack of road sense, or loss of control. Here are two main dangers: OVERTAKING. Because their machines are fast and handy, riders are tempted to take risks in order to nip through traffic and get ahead.