Slopestyle123, If they made the same bike you ride out of aluminum, same dimensions and everything... you would be correct that Steel (Chromoly)would be stronger than an all aluminum frame. Depending on the grade of Chromoly it is about 4 times the strength of 6061-T6 aluminum per unit area. that being said there are a lot of factor that go into design. One for example is that aluminum becomes weaker around the welded areas unless you post process them, Where steel does not necessarily. Also as stated before steel has equal tension and compression strengths as a material... not necessarily true for the structural shape. Where aluminum has different values that depend on a whole range of factors that I'm not going to lay out. Simply put, it is absurd to say that one bike is stronger than another based solely on the material of the frame. Each one has to be engineered to meet the same demands, so they are equally as strong.