Use Avenir's Fit Stem w/Handlebar Shims to find the perfect position on any bike. It's made from stiff 3-D-forged aluminum with a 4-bolt faceplate. And, the included shims let you run 26.0mm bars in the 31.8mm clamp.
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.