Bicycle design is a good example of where this matters: steel has a significant fatigue limit, and can endure cyclic stresses below that limit indefinitely. Aluminum has no fatigue limit, so any flexing is inevitably eating away at fatigue life. Thus aluminum bike frames have to be made much stronger and stiffer than otherwise necessary, to avoid bikes breaking unexpectedly due to fatigue. And that in turn means that aluminum bike frames don't have as much of a weight advantage over steel as you'd expect.
One advantage that adds to the potential lightness of aluminum and carbon fiber bike frames is manufacturing method. Aluminum is cheap to machine and hydroform into efficient shapes, and carbon fiber can also be layed up into efficient shapes.
Surly makes (only) steel mountain bikes, and I think there are approx. a... there's a lot of them out there. One reason is that they are inexpensive (relatively) and take a lot of abuse.
Absolutely. What I meant was that while an aluminum bike frame can be lighter than steel, it's not as much lighter than steel than you'd expect. Steel bike frames tend to be only ~15% heavier than aluminum, not 50%.
Personally I bought a steel road because the difference in weight vs the aluminum alternative was small enough that I decided to go with the bike that looked nicer, and would last longer. Besides, I could use to lose a lot more weight than any bike ever could...
Get a child trailer and load it up with groceries or cement! i tried it, the results are.. Surprising
