Steel is a completely legitimate and appropriate frame material for all but except perhaps pro-level racing (and I seriously doubt even a pro would be quantifiably and repeatably slower in comparably state of the art steel vs CFRP or Ti in a truly blind experiment if that were possible).
Ti is probably the least "green" of the contenders- an environmental nightmare to produce and in the alloys used has virtually the same specific modulus (essentially the stiffness per unit of weight/mass) as steel or aluminum or any other engineering metal save unobtainium Be-Al alloys. Ti alloys can have a small specific strength advantage over steel, but in a primarily stiffness rather than strength constrained design like a bike frame that advantage is mostly left on paper unexploited. Probably Ti's biggest assets are its natural corrosion resistance and high resistance (like steel's) to cyclic fatigue.
Aluminum's primary advantage over steel is that it is less dense which means one can make it into oversize tubes without it becoming so thin walled it will be subject to buckling failure, which in turn means a frame of equal stiffness can theoretically be made slightly lighter. But aluminum alloys are also subject to cyclic fatigue when used near their engineering limits where you see a weight advantage so with aluminum you are getting a small weight benefit at the probable expense of the lifespan of the frame. If you buy new frames regularly anyway this probably doesn't matter, but otherwise certainly might.
CFRP frames can be lightest for a given stiffness and strength but are intrinsically far more expensive to build than steel and have other disadvantages as well; The anisotropy (directionally dependent mechanical properties) combined with the high relative specific modulus of the fiber of composites mean that they can be engineered to be very strong and stiff for their weight in the directions stresses are anticipated by their designers, but that same anisotropy means they won't ordinarily tolerate unanticipated stresses as well as metal. There are also a daunting number of failure modes possible with composite construction that are far less well understood than in metal construction- notch failures, delamination, matrix voids and breakdown due to UV exposure that are difficult to diagnose and make their service life more of an unknown/unknowable. Again if you are someone who doesn't keep and ride frames over long periods, this may not matter much to you.
Looking at all this, I'd state with some confidence that many if not most users will be at least as well served by a steel frame in terms of performance, weight, value and longevity as they would with a frame made of other common materials. Honestly any of these materials can make a good bike frame and for most the decision of which to build or buy will be down to fashion and marketing considerations rather than based on engineering realities. Barring some unlikely quantum leap in material science, this picture will probably continue relatively unchanged into the foreseeable future- steel should continue to be an attractive choice where value and lifespan are important priorities.
Kurt Sperry Bellingham, Washington USA
2009/5/14 Dwight Bowen <email@example.com>:
> I agree whole heartedly. I'm a custom builder who uses only steel and I feel the resurgence. Whenever I speak to someone riding a carbon or aluminum bike they just don't feel connected to their bike. I think they want steel but their afraid to be different from their friends. They think steel is old fashioned and heavy until I tell them what my bikes weigh. It gets them thinking. However I like having the one classy bike in a group. However many of my riding buddies are buying my bikes so when I ride with them I'm just one of the crowd.
> Dwight Bowen
> Bowen Bicycle Works
> (860) 836-9765
> --- On Thu, 5/14/09, Bianca Pratorius <firstname.lastname@example.org> wrote:
> From: Bianca Pratorius <email@example.com>
> Subject: [CR] Stories about the death of steel - highly exagerated
> To: firstname.lastname@example.org
> Date: Thursday, May 14, 2009, 5:20 PM
> The future of steel is not just for KOF builders who produce in low numbers, but
> for mass produced bikes too. I am no futurist, but I feel the handwriting is on
> the wall. Wind up watches and automatics were having a bad twenty years or so,
> but now there is an enormous desire for wind-ups in the up scale market. Cotton
> shirts have made a comeback as have all wool suits. In a few more years the
> green revolution and a focus on the finer things in life will surely bring back
> home baked bread, home made sauerkraut and shaving with a straight edge blade.
> Tubed stereos are going big time as are cotton diapers. Aluminum is a practical
> but soul-less substitute for steel and carbon fiber is like a computer generated
> girl-friend or boy-friend when you're really yearning for human flesh.
> People will return to steel because it's in our iron based hemoglobin blood.
> People ultimately come back to the things we co-evolved with. The invention of
> steel is part of our human history, and whether we are talking about kitchen
> knives, samurai swords, straight edge razors or double butted Columbus tubing
> ... we have a place in our hearts that can only be filled by this material so
> Garth Libre in Miami Fl. USA