On March 3, 1972, at the Cow Palace in Daly City, California, after making a successful jump, he tried to come to a quick stop because of a short landing area. Knievel reportedly suffered a broken back and a concussion after getting thrown off and run over by his motorcycle, a Harley-Davidson. Knievel returned to jumping in November 1973, when he successfully jumped over 50 stacked cars at the Los Angeles Memorial Coliseum. For 35 years, Knievel held the record for jumping the most stacked cars on a Harley-Davidson XR-750 (the record was broken in October 2008). His historic XR-750 is now part of the collection of the Smithsonian's National Museum of American History. Made of steel, aluminum and fiberglass, the customized motorcycle weighs about .