This could get to be a heated discussion. I prefer steel. My steel frames weighs 4.2lbs and was reasonably priced at $450. Alluminum is very stiff so it has no give, none. So rather than it flexing, it will break. Now thats not to say that an alluminum frame is going to break just that it will break before it flexes. Alluminum also, because it is so stiff, tends to vibrate. It can and does actually develop a hum. Some people such as myself are sensitive to this. I can feel it in my teeth. There is also the off chance you could be biking across outer mongolia and run into an ox and break your frame. There is someone everywhere that can repair steel not so with alluminum. The biggest difference is ride quality. Go ride a salsa casseroll you will believe in the feel of steel. Plus you get to use all the ryhmes.