The Paddock car show features a motorcycle that broke the land speed record in the late 1960s.

One of the biggest draws at the precursor event to Concorso Italiano at Bayonet & Black Horse in Seaside, The Paddock, on Aug. 14 was a British motorcycle that literally looks like a missile.

“It is two wheels—that’s it,” confirms owner Steve Tremulis. “If it’s got two wheels it can fall over and it is classified as a motorcycle.”

The wheels of the Gyronaut X-1 by Triumph Motorcycle are hidden because it was designed to break the land speed record at the Bonneville Salt Flats in Utah, which it accomplished in 1966.

“At 245.667 miles per hour it held the record for four years until 1970,” Tremulis says.

The motorcycle returned to be displayed at a Car Week event in Monterey County after 12 years—the last time it was displayed locally was at The Quail Motorcycle Gathering in 2014. That event marked a century of racing at the Bonneville Salt Flats—the only place the Gyronaut X-1 has ever been raced.

Underneath the streamlined body are two 650cc Triumph Bonneville engines from around 1959, which Tremulis says are pre-units, meaning the transmission isn’t built into the engine itself. Rather a separate transmission runs outside the engines themselves. 

To pilot the speed machine, Tremulis explains that there are four controls inside the tiny cockpit, which 5-foot-9, 150-pound rider Bob Leppan used to bring it up to the top speed at the time. Similar to a typical motorcycle, Leppan’s left hand was used to operate the clutch on the bike while the right hand operated the throttle.

But two foot pedals served different functions for the transmission: the right was used for shifting gears and the left was a rudimentary brake that isn’t designed to stop the bike from over 260 miles per hour—that is used for the pits and going slow. “To slow down while racing, you have a parachute,” Tremulis says.

Other motorcycles have been designed and raced at Bonneville, making this part of the streamliner motorcycle class. Tremulis says this makes it the ultimate speed class because of the machine’s aerodynamics.

Tremulis is the nephew of the motorcycle’s stylist Alex Tremulis, and was 6 years old when the Gyronaut X-1 broke the land speed record, but has never actually seen the machine operate. When he was 10, a Yamaha streamliner ridden by Don Vesco broke the record at 252 miles per hour, then weeks later, Denis Manning broke the record again on a Harley-Davidson streamliner hitting 255 miles per hour.

Ironically, the Gyronaut X-1 team were attempting to take back the land speed record from Vesco when Manning broke it, but Leppan did break it again using a blend of Nitrous Oxide as fuel, which caused him to get it up to 264 miles per hour in 1970. But at the end of the next run, the front suspension broke, almost costing Leppan his left arm in a crash, and the bike never ran again.

“The crash really preserved the bike,” Tremulis says. “What Leppan and the team wanted to do was put the Trident engines in it.”

Tridents are three-cylinder engines, which would effectively make a six-cylinder engine for the motorcycle as opposed to the two Bonneville 650 twin engines.

After Leppan’s crash, the only way to make the motorcycle run again would have been to cut it up and rebuild it, meaning nothing would be preserved as original like it is now. Tremulis bought the motorcycle after Leppan offered it after it spent years in storage.

“It was missing the canopy and the engine cover. Leppan didn’t know how to do fiberglass,” Tremulis says.

A call was put out on the internet and a hot rodder and custom fabricator named Rob Ida answered. It turns out that the main restorers of the motorcycle were the grandkids of Preston Tucker, developer of the Tucker 48 sedan.

“It was a full cycle of life,” Tremulis says.

The Gyronaut X-1 now stays with Tremulis in Redwood City when it’s not loaned out to museums.