Bicycle Crunch - one of the best there is

This is one of the best exercises for your abs and obliques... especially lower abdominals and external obliques. Because of bicycle like movement there's still a tension, which works your abs in a ways that ordinary crunch can't. Great for both females and males. To make it harder:

• do it more slowly
• extend your legs
• or focus on precise turning of your upper body

Try it for your self and let me now, how it works ;-)