It may confuse people to discuss "longevity" and "warranty" in the same post. These are two very different issues. A "warranty" covers a defect in material or workmanship at the time the bike left the factory. A warranty does NOT cover accidents, wear and tear, fatigue, or longevity.

When a bike company says that its frame is guaranteed "for life", that only means against a defect that was present when the bike left the factory. These days, it would be rare for ANY defects to be found in a frame from a company such as Cannondale. So, a "lifetime" frame warranty almost has no meaning. It is a warranty against something that is NOT going to happen.

I suspect the Cannondale website included the language about "life span" of a frame to "educate" buyers that ALL frames could fail someday, if ridden long enough, and ridden hard enough. I have never seen a road bike frame that was made in the USA fail under normal use (of course, "normal use" does not include the stuff my nephew does with his bikes - who knew you could ride a bike at high speed off a two foot tall loading dock? Over and over, even...)