Colin Unsworth and Sadie Tann, who have already visited the Capital in their quest to raise money for charity were deliberately knocked off their tandem.
Police are appealing for information after a driver reportedly swerved at the pair twice, knocking them off their bikes the second time. Police are trying to trace the car and its driver.
Speaking to the Daily Mail, 52-year-old Colin said: “It’s really shaken us up. On the live video you can see the driver pass us in the opposite direction and then they’ve turned round and come steaming back down to catch us up.
"I’m quite a skilful cyclist, I’ve been glued to a push bike saddle all my life, and I managed to avoid the first swerve. But as I slammed the brakes on to come to a stop he swerved again and hit us that second time.
"He knocked us to the floor. We weren’t injured as such, just a few bruises and scrapes.
"At the time I just got back on my feet and thought it’s fine, we’re not injured, but that night I didn’t half have a sleepless night thinking about it.
"We are very, very vulnerable, being naked on a bike."
A Police Scotland spokesman said: "Police inquiries are ongoing after a 52-year-old man and a 31-year-old woman who were riding a tandem bike were deliberately driven at and struck by a car on the A912 near to Bridge of Earn at about 2pm on Monday."