The committee says performers have been rehearsing to make sure the ceremony directed by Danny Boyle doesn't drag on. The International Olympic Committee has pressed to keep the ceremony tight so athletes can get enough sleep.
The bikers will still be paid and credited.
Some 10,000 performers will be involved in the 2012 opening ceremony, which will be held in front of 60,000 spectators inside the Olympic Stadium in east London. A television audience estimated at 1 billion is expected to watch.
Boyle acknowledged the challenges of staging a large-scale show for live TV - not least capturing the British sense of humor.