Possible Clues:

• First name in macho stunts
• Big name in stunt riding
• Stunt-doer Knievel
• Stuntmeister Knievel
• Motorbike daredevil
• '___ Knievel To Attempt Huge Leap In Logic' ('The Onion' headline)
• Motorcyclist Robbie's dad
• First name in awe-inspiring jumps
• First name in jumps
• Knievel who called himself 'the last gladiator in the new Rome'