Offsets will be offered in 25 and 15 millimeters for starters, because Pacenti says that exceeding those numbers creates unstable steering as the grips of the handlebar move behind the steering axis. Fabien Barel concurs, relating that he tried zero-rise stems, but had to move the bar forward ten millimeters to stabilize the Mondraker's "Forward Geometry" steering.



Concerns about weakening the handlebar at the center where, theoretically, the bending forces are highest are unfounded, says Pacenti, who showed a computer-generated stress model that indicated the stem's two clamps arrest all the major bending moments, leaving the center of the bar almost unaffected by those forces.



Another concern is that customers are being asked to purchase a matching bar and stem for each of the two offset options. Pacenti says that he will offer bars with a ten and 15 millimeter dimple that will nest with his 25 and 15-millimeter offset stems. Logically, the deeper, 15-millimeter dimple would fit both stems, but Pacenti insists that doing so would eliminate the self-centering effect of the closely fitting bar. He also claims that the limited angular adjustment of the correctly matched Pdent stem and bar will prevent the bar from over-rotating should the stem clamps be under torqued.



Surely, those features are optimal, but in the same breath, neither are critical to the system's purpose of providing a shorter stem to the many riders and bike makers who believe that the option will turn in a better performance. If I were a customer, I'd probably buy the bar with the deepest dimple, knowing that I could upgrade to either stem option should I have guessed wrong.



Sub 30mm stems have been around for a while, but they are typically 30 to 50 millimeters taller than conventional stems, because the handlebar must be positioned above the steerer-tube clamp.