Originally Posted by 2door
If you rely on a tubular seat post then bending it will always be a possibility. Like was said above, the longer it extends to the rear, the easier it will bend (more leverage)
If you have access to a lathe and a source of heat you can fabricate your own post from solid bar stock. Most seat tubes will require a 1" seat post that tapers to 7/8" where the saddle mounts. I've made several with a lay back of six and seven inches. Never bent one yet. A friend in the metal working business would be a plus here if you don't have the necessary tools.
This is an example of Tom's work. This thing is awesome and what ever motorized bicycle I am ridding, this post gets moved to. A 600 LB rider could not bend this if (s)he rode off a cliff, cought fire and insulted alkida. Well worth making or having one made.
A bent or lay back seat post is the best bang for the buck upgrade I know of.