Passengers with fold up bicycles with small wheels that are belt driven are permitted to travel on Transperth buses at any time as long as the bicycles are contained within a carry bag exceeding no more than 86cm long x 68cm high x 36cm wide. Fold up bicycles must be kept out of the aisle.
Seems they don't want folders at all as I think the above criteria is nigh on impossible to meet. The only folder I can find for sale in Australia that has belt drive is the Strida, but it doesn't fold down into the dimensions they want. There are a few chain driven ones that do though. Why Transperth wants them to be belt driven when the policy states they have to be in a carry bag confounds me.