Originally Posted by Oznerol
Get out of the saddle and learn to position your weight in such a way that you're balanced between the need to keep the front end down and the rear hooking up. I know that bending my arms and getting my chest close to the handlebars helps a lot with this.
You have to 'row' your bike when it gets really steep. Pull the bars back and down to drive the rear wheel into the ground.
The steeper the climb, the farther forward you need to sit on the saddle. If its really steep, you're all the way up on the tip of the nose of the saddle.