DC, not many know those names. I appreciate that you do. They have my respect.
Although Steve McQueen was very capable of doing the riding himself, Bud Akins, an off-road and desert racer and close friend of McQueen's did the bike riding in "The Great Escape". The bike was actually a Triumph 650.

He and Steve McQueen, Dick Mann, Bad Brad, Joel Robert and Evel Knievel are all members of the AMA motorcycle Hall of Fame.

I raced aginst Dick Mann in the 70's in the Granite City summer AMA pro short track series, he was in his 40s, me in my teens.
For sure the best all round motorcycle racer ever. He's still riding and building bikes.

Evel Knievel did a jump there one night, great showman, appreciated what we were doing. Drew a much larger crowd for the races which up't the purse considerably. And since he didn't splatter, he was able to us in our routine after races beer and whisky binge.