Steel bikes have been around for 120 years. As recently as 1990, steel bikes had about 95% of the market for bike frames. Most frames that fail ought to be at least ten or fifteen years old...and the majority of the bikes that old have steel frames...obviously then, most frame failures OUGHT to involve steel frames.

If a steel frame failed "just riding along", and it was less than ten or twenty years old, odds are the tubes were improperly joined (a problem in the 1970's, when US bike sales went from a million adult bike a year to over ten million adult bikes a year). And, if tubes are not joined properly, the joint is gonna fail regardless of which tube is involved. And, a steel tube that fails from rust? Well, if someone is silly enough to allow water to sit in their bottom bracket for a year or two...

The REAL data on aluminum frame failures will be coming in five years or so, when there will be a larger number of aluminum bikes around that have ten or fifteen years of riding history. Will a lot of 1995 aluminum frames be on the road in 2015? I have doubts.

But, there is also a difference between HOW steel frames fail, compared with aluminum, or carbon. If a steel frame is poorly made, it fails at a joint between two tubes or at the bottom bracket. If a steel frame is well-made, it can fail from rust (which is preventable) or from thousands and thousands of miles of riding, after decades and decades of hard use.

A well-made steel frame dies of old age. I have half a dozen steel bikes that are fifteen or twenty years old. All are in perfect riding condition today, and are likely to be on the road when they hit age thirty.

In comparison, failures of aluminum tubes and carbon tubes are often very sudden. Unlike steel, where a small crack might develop into a large crack over a period of months and years, aluminum and carbon frames can fail with zero warning, even when relatively new. When stressed beyond its limits, a steel tube bends. An aluminum or carbon tube snaps.

Aluminum frames came along at JUST the right time. Aluminum frames became popular in the 1990's, when America was becoming a "throw away" culture. I often hear someone with an aluminum frame say "This bike is three years old...I'm gonna get rid of it". An aluminum frame that has gotten ten years of daily use is a rare beast today, and is likely to always be a rare beast...most folks buying aluminum bikes don't intend to keep that bike ten years...old age will not be an aluminum issue.