Originally Posted by
gregf83
You wear them out by riding them. My Colnago, which I had for about 10 years, cracked near the bottom bracket. Wasn't worth it to fix it. Metal fatigues over time. Carbon bikes are built much heavier near the bottom bracket so there's less flexing going on.
What kind of Colnago?
My Colnago Super is nearly 50 years old, and has lots of miles, probably 30 to 50K, give or take a few. Of course there are many more bikes with more miles, or more years, but a steel frame commuter can do well for quite a while. If you're doing 200K or more... then it is time for a new bike.
I did buy a Colnago BiTitan with a cracked frame, but perhaps that was as much of a design flaw as a problem with the titanium.