A man on a bike was stopped at the border by police

A man on a bike was stopped at the border by police assigned to investigate goods transported across both states. He carried a bag of sand. On perusing through however, the cop found nothing else in the bag and therefore let him go. The next day this man was stopped with his bike and a bag of sand and the same process carried out. Again, he was let off when the cop found nothing illegal. This sequence carried on for three years. One day both men, the cop and the bike guy, met at a pub. “Tell me, man,” said the cop, “I promise I will not tell anyone; but what were you smuggling all those years?” Surprised, the man looked at this professional, laughed and shrugged. “Bicycles,” he said.