G'day,

There are no rules!.....however, to qualify as an 'audax' ride (international cycling organisation) any distance must be covered at an average speed of no less than 15kph. this means that you can have as many rests as you want, but your total elapsed time, (time from when you started the ride, to when you finished), must come in at an average 15kph, (9.38mph). therefore, to qualify as a 'century'....you have almost 11 hours, start to finish, to complete it....

cheers,

Hitchy