Chalktrail for Bikes
I think all kids should be given a Chalktrail and told to ride however they want around a big open driveway or parking lot. Then when they've finished a bunch of child psychologists can come in to examine and assess their drawings, the results of which will be used to determine which tykes are most likely to be professional athletes, which have a predisposition towards proving the unified field theory of physics or creating the next Facebook, and which should be kept away from sharp objects and living creatures and possibly exorcised.
I also think the chalk-wielding bike attachment shouldn't be marketed so heavily to kids only, as I would like one too, and I'm pretty sure--as evidenced here--that any whimsical whirlique I might draw will be exponentially better than the erratic crap they pedal out.
The Chalktrail fits on bikes with wheels 12" to 29" in diameter, and its included fresh piece of chalk has a drawing life of 15 miles. I'm certain 15 miles is farther than I've ever ridden a bike in my entire life. Cumulatively.