REAL DEFINITION:
A moustache that is long, and sticks out from the sides of your face, like the handle bars on a bike. The ends may curl, or they may just stick out like dangerous facial hair- daggers. The other moustache listed (curving down beside your lips) is a variation on the Fu Manchu Moustache (think crazy Asian guy moustache)
Motherly advice from Tyra Banks on cycle 16 of America's Next Top Model. The handlebars of fierceness alludes to when one achieves the pinnacle of amazingness usually when being photographed, or in any other stressful situation.
Tyra (to inconsistently performing model): You need to grab the handlebars of fierceness and not let go.