I am having a difficult time understanding that myself. I have come across some aluminum frames, one was a Giant Cypress DX I saw at a local salvage yard, which had no corrosion at all. It could still be built up into a decent winter bike with the right parts. Recently, I test rode a Specialized Allez, their most basic model road bike. It handled better, felt smoother, and seemed far more efficient than the Raleigh Marathon (which I sold to a commuter) I had recently. The only real difference I've found between steel and aluminum is that steel stands up better to bending, welding, and shaping. Although steel is easier to work with when frame building, aluminum is going to offer better corrosion resistance. As long as an aluminum bike has not been involved in any accidents, it will last for many decades, just like a bike with a steel frame. The feel of a bike, when riding, is going to depend on its build and geometry more than the materials it was made of.

Carbon frames are the thing now days. The only concern I have for them, is that the material likely to be less forgiving than steel or aluminum. For example: With a steel frame, the stays can be cold-set to accommodate a wider rear wheel set if one wishes to convert from a 5-speed hub to a 9-speed. This cannot be done with aluminum or carbon. However, it is getting increasingly difficult to find new components for old steel frames that were designed specifically for 27" wheels and tires, and the selection is extremely limited. For those reasons, I will recommend a recent-model 700c aluminum bike over an old steel bike for general riding. Short hops or long miles, it will be far easier to tune and maintain the modern aluminum or carbon frame bike than the older one made of steel because the parts are readily available, and the local shops know how to service them.

Will the aluminum bikes be collectable in the years to come? Well, I think much of that will depend on people's experience with them. I personally like bikes with bright and interesting colors and patterns, but don't care for gray or black; at least not on a collector's standpoint.