Bontrager's Rhythm Pro Stem is engineered for the rigors and punishment of aggressive, all-mountain riding. Thanks to its forged 7050-T6 aluminum construction, it's strong, light and stiff. The CNC-machined 4-bolt faceplate is ultra tough and evenly distributes the clamping force on carbon bars. And, the opposing 2-bolt steerer clamp is safe and secure, even for carbon steerers.
Stem length is measured along the side of the stem from the center of the steerer to the center of the handlebar clamp (see diagram). Keep in mind that as a stem provides more rise, its effective length decreases. In the example above, if the +17-degree stem measures 135 mm, it actually extends 108 mm parallel to the ground.