ProTaper JUNIT Youth Handlebar - 680mm 12.7mm 1/2" Rise 31.8mm Aluminum Stealth BLKProTaper JUNIT Youth Handlebar 1 2" Rise Stealth. Hayes Performance Systems product development team set out to design a system for kids using high quality and high performance components. The JUNIT ProTaper handlebar is one part of this two part system. Our Engineering team began by researching anthropometric data from a NASA database and determined the average hand size of a 6 10 year old which set the team into motion. Normally grip diameter is a