I came from hardtail mountain biking where you tend to hover over the rear seat when descending to help absorb impact. I orient my cranks parallel to the ground, hover about an inch off the saddle and grip the saddle with the insides of my thighs. Keeps me aero, gives my butt a break, and keeps me stable. This is only when I spin out my cassette though. Until that point, I am seated and pedaling.