Winds of up to 60km/h wreaked havoc at the Cape Argus Pick 'n Pay Cycle Tour on Sunday, collapsing tents and scaffolding.
A woman broke her arm when the breakfast tent at the start of the race collapsed with her inside, said joint operations manager for the event Brad Geyser.
She had since been taken to hospital to have the broken limb set.
"The wind did us a lot of damage. We didn't expect it to be this strong," said Geyser.
The start of the race itself was delayed 54 minutes because of the wind, with wind speeds of 40 km/h measured at Chapman's Peak and 60 km/h elsewhere on the route, he said.
Scaffolding erected at the Allan Gray building, near the finish line, collapsed, crushing three cars, but injuring no-one. A tent at the finish line came down too.
Most of the structures erected for the race at the start and finish lines had to be taken down because the wind was so severe, said Geyser.
The Greenpoint stadium construction site, where most of the hospitality tents were erected in sandy ground, became a "dust bowl" which the fire department had to water down, he said.
A number of smaller tents had been taken down. Bedouin tents had been used as an experiment this year because they looked nice "but they didn't like the wind", he said.
Geyser said heat was not a problem during 2009's race, because the wind had a "cooling effect".
In some areas there was such a wind chill factor that cyclists had to be warned not to stop.
Considering the circumstances, there were relatively few casualties during 2009s' race, Geyser said.
In one of the nastier incidents, a woman cyclist hit the tar face first in the Perdeberg area, breaking both collar bones and sustaining scratches on her face.
Another cyclist's ribs were crushed when he came off while going down Chapman's Peak.
A doctor on a motorcycle immediately attended to him and he was taken to hospital right away.
Geyser said 71 people had to be picked up by ambulance during the race.
Of these, 32 were admitted to hospital. Thirteen of them had since been discharged, while 19 would stay in overnight.
"This is a lower number than 2008, he said.
The injured had sustained mainly fractures (of ribs and arms), scalp lacerations, clavicle breaks, or were asthmatics or people with gout.
There were a handful of more serious cases where patients had to be resuscitated after experiencing shortness of breath or chest pains, he said.
No serious leg breaks or impact head injuries had been reported so far in 2009.
Geyser said the organisers hoped to restore traffic normality to Cape Town after 4.30pm.
Although 35 000 cyclists entered in 2009, only 25 600 started the race, said the organisers.
The wind had resulted in much slower times than usual, they said.
The cycle tour was won by Arran Brown, of the Medscheme team, in two hours 46 min 32 sec, with Robbie Hunter, of Barloworld, in second place and Nolan Hoffman, of Neotel, third.
Brown also took honours in the sprints and the award for the most consistent rider, while Briton Stephen Cummings, of Barloworld, was king of the mountains. - Sapa