Zirconium Rear Sprocket. The Dirt Tricks Zirconium Rear Sprocket is part of the next revolutionary change in weight and color! The Dirt Tricks Rear Sprocket was designed and patented by Dirt Tricks president and engineer Greg Burns in 2002, using his knowledge of aerospace steels, heat treatments, as well as FEA stress analysis. Being an expert desert racer, Greg became tired of changing aluminum sprockets every two months. His goal was to create a sprocket that would last an entire season of hard riding, yet be comparable in weight to aluminum. Thus, the Dirt Tricks sprocket was born. It required two years of development and testing, but the end result has proven to be the toughest, most durable off-road sprocket available. The new Zirconium sprocket design comes in two colors and is two ounces lighter than the Dirt Tricks chrome-plated sprocket.