With the growing popularity of Fat Bike Racing, the ABA has set out a few regulations that need to be adhered to during Fat Bike Races.
The regulations fall under the Mountain Bike Regulations found here.
4.8 Fat Bike
4.8.1 The course may not be held on or across a frozen body of water.
4.8.2 Without prejudice to the relevant legal and administrative provisions and the general duty of care, the organiser shall ensure that the race course or the competition grounds include no places or situations that could constitute a particular safety risk to anyone (riders, attendants, officials, spectators, etc.). (UCI regulation 1.2.061)
4.8.3 Wheels of the bicycle may not incorporate any form of spike or stud.
4.8.4 Events may not take place in instances where the temperature drops below -20C.