Merckx set the hour record in 25 October 1972. He covered 49.431 km at high altitude in Mexico City. The record was unbeaten until 1984, when Francesco Moser broke it using a specially designed bicycle. During the next 15 years, various racers improved the record to more than 56 km. However, because of the more and more strange designs of the bikes and position of the rider, in 2000 the UCI said a "traditional" bike must be used. When Chris Boardman had another go at Merckx's reinstated record in 2000, he beat it by slightly more than 10 metres at sea level. But, Merckx had raced a full road season winning the Tour, Giro and four Classics, while Boardman was a time trial specialist who had retired from road racing and had prepared specially for the 2000 Hour Record.