As a child, learning to ride a bike vexed me to no end. While my friends zipped around the neighborhood on two wheels, I plodded along on four, thanks to an embarrassing set of “training wheels.” Good ...

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.