The Yamaha DT250 motorbike Robert Redford rode in The Way We Were (1973) will auction through website CharityBuzz.
It's expected to sell for around $20,000-30,000.
Bidding stands at $15,000 ahead of a close date of October 28.
The proceeds will be donated to the Redford Center, which uses film to foster discussion about social and environmental issues.
Redford was gifted the bike by the producers of Little Fauss and Big Halsey in 1971, a film in which he stars as a professional racer.
During his younger years he was a keen motorcycle fanatic and remains passionate about the hobby today.
The organiser of the sale, Redford's son James, comments: "He wasn't that interested in things like license plates and registrations and would often talk his way out of tickets.
"One time we were riding in the foothills of the Utah Valley and we went off the road to avoid a stalled car.
"Dad flipped right over the handlebars and landed on his feet in a crouch. Dad in a nutshell!"
The winning bidder will get the opportunity to meet both James and Robert Redford in San Francisco.
Few pieces of memorabilia from Redford's career have been offered on the market before, making this a prime opportunity for collectors.
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