In this YouTube video of Cancellara you get to watch him descend down a hill like a pro.
There are two hand positions. The first is the in the drops. The second in on the tops either side of the handle bar stem. The second position is much more unstable and… as your hands are further way from the brakes so it’s a lot more dangerous if you need to slow down for any reason.
Generally you’ll use the drops position for roads with a lot of hard corners where you need to use the brakes to slow down to go around them. Make sure that when you start practicing these techniques you are on a safe road away from other riders and cars in calm non-windy conditions.
Another tip is to ensure that your arms are relaxed. That way you can absorb the shock coming through the bike from the road. If you tense up you are guaranteed to get your bike into a speed wobble or worse still, totally lose control and crash.
While the aero tuck is an advanced descending technique if you are struggling to just let go of your brakes at any time on a decent I have a simple tip for you that I teach descending novices.
The main reason why people hold on to the brakes all the time on a decent is because they just feel out of control at higher speeds. What I get the cyclist to do is when they get to a long straight that has no bends while descending down a hill I ask them to just release the brakes a little so that the bike builds up a little more speed. Once they feel uncomfortable with the speed they are asked to apply the brakes a little to bleed off the speed.
This is done gradually so that the cyclist slowly gets used to travelling faster on the bike downhills. Over time this simple technique helps build confidence in the cyclist so that they can start descending faster.
Remember: Always take care when descending and always ride so that you’re in control of your bike and within your comfort zone. Never take risks while descending as you can kill yourself.