This was so stupid I just had to post it…
well, a man DID win this time, tho… 
They seem rather serious with this race.
The first race took place in June 1980. In 1982 the course was changed to provide a more even match between man and horse, and in 1999 the fastest horse beat the runner by only 80 seconds.In 1985 mountain bikes were introduced to the race and Jacqui Phelan, US Ladies’ Champion, was just minutes behind the first horse. In 1989 Tim Gould, Cycles Peugeot UK, beat the horse by nearly 3 minutes. This was the first time the winning horse had been beaten by a mountain cyclist and Tim won £5,000 from William Hill for his fine achievement. The bookies also had to pay out a bonus in 1995 and 1996 when a relay team came home ahead of the first horse. Unfortunatly, mountain bikes have not been allowed to participate in the races held since 1994 because of an anomaly in the law, which forbids bicycles to race on bridalways. The Department of Transport has recognised this and proposals to change the law are being sought.