Want to sit on the same seat that Pippa Middleton’s famous backside once graced? Here’s your chance! The Duchess of Cambridge’s younger sister recently rode her bike across the United States as a participant in Race Across America to raise funds for two important charities, and now she is auctioning off the bike she used during the race to benefit the same causes. Middleton added her signature to the custom Dassi bike, which was specifically designed to optimize her performance during the race that took her eight-person cycling team from Oceanside, Calif., to Annapolis, Md., in nine days.

All proceeds from the auction will go to the British Heart Foundation, which helps power research into heart disease (Middleton is a BHF Ambassador), and the Michael Matthews Foundation, a nonprofit that works to provide an education to children around the world who are unlikely otherwise to receive one.

“The challenge of riding across the Rockies, coping with the heat of the Arizona desert and climbing over 170,000 vertical feet in the six days was incredibly tough, but every inch of the 3,000 mile race was worth it, to help the BHF fight heart disease,” Middleton says in a statement. “I wanted to complete this challenge to help raise awareness of the importance of heart health after learning that coronary heart disease kills nearly three times more women than breast cancer. So whether you’re inspired to get fit or you’re a cycling fanatic wanting to add to your bike collection, take a look at my bike and put in a bid. I’m keen to raise as much money as possible to help the BHF fund life-saving heart research.”

Bid on Pippa’s bicycle now through Aug. 13 on ebay.com.

Want more? Check out Pippa Middleton’s best style moments in our gallery.