Osymetric O-14 4 Arm Chainring 110mm BCD $164.50
Every watt out of every stroke.
With the introduction of testing power and measuring exact watts created in various phases of the pedal stroke, cyclists have been looking for ways to reap every watt possible out of every degree. Osymetric has the latest theory in how to transfer the most power from your legs to the drivetrain with its dual-cam-designed chainrings.
Essentially, even though cyclists are taught to "round out" their pedal strokes, very few actually are able to fully execute it well. And while an ovalized ring maximizes power for part of the stroke, the dual-cam more effectively minimizes the dead spot in the pedal stroke. The Osymetric chainring is the brainchild of French engineer Jean-Louis Talo. The radically-shaped chainrings use a dual-cam design, with each cam lobe corresponding to the most powerful part of the pedal stroke: the downstroke. The design increases the gear inches of the chainring at the point where you’re able to apply the most force, but as you transition to your least powerful part of the stroke, or dead spot, the chainring reduces in size to speed you back into the power part of the stroke. For instance, an Osymetric 52-tooth chainring would be similar to a 55-tooth in the largest portion of the cam, then gradually reducing to a 49-tooth over the dead spot. This translates to a claimed 3% increase in speed.
As a note, to install the chainrings, you'll need to make adjustments to the derailleur height and width with the included screw. And you'll also need to spend time fine tuning the rear derailleur. The first ride may seem a bit awkward, but after a few times out you'll feel more power in your stroke and be less aware of any inconsistencies in chainring shape.
The O-14 is for the new four-arm Shimano Dura-Ace and Ultegra cranksets. They are available as small and large chainrings in 38t, 42t, 50t, 52t, and 54t.