Getting used to "racing position" on a road bike

[OakLeaf]

+1 on checking your fit. Aerodynamic fun aside, the main reason to be tucked on a descent is because your center of gravity is lower, you have better control of your weight distribution between the wheels, and you should be *more* stable (and have a better grip on the brakes if you need them). Practicing on the flats to get used to the position and build core strength is a good idea, but feeling stable vs feeling natural/comfortable are two different things, and my thought is that if you don't feel stable, something is probably off with your fit.

Point of terminology that got addressed in another thread ... when you're tucked for a descent, you want your hands in the hooks, the curved part of the handlebars with the closest reach to the levers. If your hands are on the lowest part of the bars that point back toward you, it's not surprising that you would feel unstable that way.