Interesting to see the differences between countries.

In Australia, you cannot be booked for speeding on a bicycle because bicycles are not legally required to have devices capable of displaying speed. Doesn't stop the cops from waving you down and giving you a hard time, however. Also, down here, if a cop paces you in his car and claims you are speeding, you can usually successfully beat that one in court based on previous case law.

Speed cameras and radar guns are a little harder to argue with, you have to sell the judge some tale of tragedy and woe, like "I was bitten by a venomous snake and was racing to hospital for treatment".