[Jeff in Kentucky]

from the third paragraph in the first post:

During the Great Escape movie filming in 1962, he had a TT Special 650 Triumph painted olive drab and made to look like an old wartime BMW- the old BMW rigid suspension and less powerful engine would not take the speeds they were running. McQueen played both the escaped prisoner and the Nazi chasing him on a sidecar motorcycle, with the scenes intercut. The big jump was done by his friend and expert rider Bud Ekins.