The CIC Events-managed Gran Fondo World Championship is the first of two Perth events, with the final in September.
Subiaco-based promoter Scout said the one-day 143km challenge was a tough race and the competition had been months in the planning.
“This is the first time a world cycling championship has been held in Perth,” she said.
Gidgegannup farmer Suzanne Blumer said she was in disbelief on hearing Toodyay Road would close for two hours, for a cycle race.
She said the treacherous road was the only route for emergency services, including fire.
“Volunteer firefighters have to travel to the fire depot in Toodyay Road to collect fire trucks, and last weekend there were 15 fires in Toodyay,” she said.
“Toodyay Road is ranked as one of the most dangerous roads in WA; it is narrow and winding, there are very few passing lanes and even fewer turning lanes.”
The sheep breeder said the road closure would inconvenience delivery of cattle to Muchea Livestock Centre, visitors to Brigadoon Equestrian Centre and residents wanting to drop off waste to the eastern rubbish tip.
Ms Blumer said there were no alternative routes for local farmers to use and Sunday was a busy day.
“Who in their right mind would permit Toodyay Road to be used for a cycle race?” she said. “Why not use a national park or reserve?”
Champion professional cyclist Gary Wright, of Victoria Park, shared her concerns.
“He (Wright) told me the event was not for professional cyclists and only for those prepared to pay $500 to $600 to enter, with all proceeds to CIC Events,” Ms Blumer said.
The promoter said about 1400 ‘professional amateur’ cyclists will participate in the challenge.
“They are not Tour de France riders, but they have to cycle a certain distance within a given timeframe,” the Scout spokeswoman said. The top 25 per cent of competitors in today’s qualifier will compete on Sunday for a place in the September final.
Main Roads said emergency services would be escorted through closed roads immediately.
Road closure traffic information and maps are available at www.granfondoworldseriesperth. com.au/gran-fondo-road-closures.