You might be surprised. In the aftermath of Hurricane Katrina I didn't have access to a car and instead rode my dad's ridiculous full-suspension Schwinn (from Walmart) to and from work. This was a 3 mile round trip on flat asphalt. After two weeks, the weld joining the downtube to the bottom bracket actually split open entirely, leaving the bike held together by the suspension and chain tension.

This bike was only a year old at that point; clearly it wasn't designed to be ridden beyond an initial burst of post-purchase enthusiasm. It's the only time I've ever seen the failure of a bike frame.