(dpa) - Normally, runners in San Francisco are afraid of the famous city's tortuous hills and bone-chilling fog.
But as footage of violent protests from the global Olympic torch relay was beamed around the world in recent days, the relay runners in San Francisco had other fears on their mind.
"I am hopeful that my fellow human-rights activists will not condemn me for this," said Helen Zia, a noted American-Asian author and human-rights campaigner.
Zia, 55, is one of about 50 runners chosen to carry the torch during its only journey in the US.
What was meant to be a celebration of the Olympic spirit and a moment of celebration for San Francisco's prominent Chinese-American community has instead turned into a huge controversy.
The growing uproar is part of the biggest political threat to the Olympics in a generation - since the boycott of the 1980 Moscow Olympics by 62 countries in the aftermath of the Soviet invasion of Afghanistan, and the Soviet-led retaliatory boycott of the Los Angeles Games four years later.
Police in San Francisco said they are taking special actions to protect the torch, which had to be extinguished three times in Paris because of protests, before organizers in the French capital decided to cut short the route.
Precautions were powerless Monday to stop three intrepid climbers who scaled San Francisco's landmark Golden Gate Bridge to unfurl banners in support of independence for Tibet.
"We are part of the global independent movement for Tibet, and we are calling the world's attention to what's happening in Tibet right now," protestor Laurel Sutherlin told a local TV station as he dangled more than 50 meters above the bridge.
"China is trying to take this Olympic torch around the world and use it as an opportunity to become a global player. We are looking to unmask this propaganda and let the world know there's brutal oppression happening in Tibet."
The stunt on the bridge coincided with a call by US Senator Hillary Clinton, the Democratic presidential hopeful, for George W Bush to boycott the opening ceremonies in August in Beijing.
Clinton also cited China's failure to use its influence with the Sudanese regime to halt the Darfur conflict, which had human-rights activists railing against the Beijing Games even before the unrest four weeks ago in Tibet set the pot boiling.
Oscar-winning Hollywood director Steven Spielberg resigned two months ago from the organizing committee of the opening ceremony to voice his protest, while an organization called Team Darfur is rallying athletes from around the world to raise awareness about the crisis in the Sudanese region.
Given San Francisco's reputation as a radical bastion that enjoys nothing better than a good protest, the embarrassing scenes of mayhem that accompanied the torch in Paris and London are likely to be repeated on US soil.
City supervisors last week adopted a resolution calling for the torch to be greeted with "alarm and protest." That was seen as a slap in the face to the city's Chinese-American community, which makes up a third of the San Francisco population.
"On what moral ground does a country that's been involved in the slave trade in Africa and that drummed up false charges to invade Iraq shake its finger and lecture China?" asked Rose Pak, a prominent community activist.
"They're turning this whole thing into something ugly. Chinese people thought they had a moment to be proud. Now they'll stay away, bewildered."