Once upon a time, ENVE only offered one stem. It pulled double duty for both road and mountain duty and thanks to its lightness and toughness afforded by its unidirectional carbon fiber construction, it handled both quite well. But as mountain bike geometries evolved, the need for mountain-specific lengths and construction were needed. Around that same time, ENVE began sponsoring World Tour Team Dimension Data and because at the highest level of road racing, aero is everything, the team asked ENVE if it could create a stem with more drop to facilitate a long and low position on the bike the riders were after, and one with a slippery profile that when paired with its bars, especially the SES Aero or Aero TT bars, would be a little more hidden from the wind. ENVE obliged and the result is the SES Aero Road Stem and if you're a road racer or triathlete and are looking to optimize your position and improve your bike's aerodynamics without sacrificing stiffness, weight, or ride quality, this is the one for you.
ENVE attacks the aero quandary on two fronts, it's adjustable, both in length and angle, which places the rider in an aggressive, faster position, and the stem's profile is designed and shaped to better slice through the wind. It's important to note that this stem is intended for a negative drop only and cannot be flipped or reversed to a positive rise. Since the rider makes up the majority of aero drag, a lower position is often much more meaningful reduction of drag than an aero helmet, frameset, or wheelset and because the stem's angle adjustability allows you to dial in your handlebar height without having to resort to additional headset spacers, it allows for cleaner airflow at the front of the bike, saving valuable watts. The rounded versus blunt faceplate combines with the hidden titanium bolts to further reduce the frontal area.
The Aero Road Stem comes with 2 shims, a fixed -12-degree angled shim that depending on its orientation offers a 2.5mm length increase or decrease, and another shim allowing for a less aggressive -7-degree rise or you can flip it around for the Euro pro's favourite, -17-degree.