Mountain bikers are tying themselves in knots over wheel sizes at the moment. For decades they were 26 inches across and everyone was happy. Then came 29 inch rims, which were supposed to roll over ...

These Dartmouth College engineering students are battling scraped knees, one two-wheeler at a time. To help kids learn to ride a bike, the team placed a flywheel inside the front wheel of a 16-incher.

Being the fine physical specimens that we are, even from an early age, we of course had little trouble learning how to ride a bike without external help, but we're sure **some hapless child out there ...