Karts occasionally use a shaft adaptation spider instead of a solid sprocket, this allows inexpensive and rapid tooth-count changes by having a chainring instead of a sprocket. Chainrings can be found in steel, aluminum, and composite materials...also using a chain pitch of #25, #219, #35, and others...The decision to have 6-holes in the mount was made in order to allow the option of having two "half moon" chainring sections, which allows the chainring set to be changed to a different tooth-count without needing to remove a wheel from the Kart
The standard Kart spider interface is 6-holes/6mm diameter each, in a Bolt-Center-Diameter (BCD) of 5.250-inches