When efficiency AND aerodynamics are critical, our new EVO AERO System is the top choice for many! The original Hyper AERO System has been proven at KONA with a 7th place finish (Braden Currie) in it's world debut and countless other top finishes around the world throughout the past 12-months...and it just got better! Utilizing a 14-Tooth / 18-Tooth pulley wheel combination, the new EVO AERO System is unmatched by any competitor on the market when it comes to strength, durability, performance, and aerodynamics! Reducing drivetrain friction and aerodynamics does not have to come with a trade-off of decreased durability, decreased shifting performance, or even taking an aesthetic step backwards (current offerings on the market). Improve your current stock drivetrain or even your current competing Oversize System with the installation of an EVO AERO System. Every EVO AERO System is designed, tested, and hand built in Pawnee, Illinois USA.