We’ve just had word from absoluteBLACK that they’re moving into production of oval chainrings, and are claiming to have the powerzone nailed to make the most of your pedalling input.
Here’s what we know:
How do they work?
They do not produce more power. They just make you quicker by clever distribution of your energy. They are very similar to Rotor rings in terms of shape and clocking of the power zone. Trouble is that other companies claim that these produce more power instead of just explaining how they really work. This is simple mathematics of leverage.
So with an oval ring, you push a “larger” gear (greatest radius of the oval), only in the power part of your stroke (= cranks slightly below horizontal). Then your leg speed increases a bit through the rest of the stroke as if you were pushing a smaller gear. You do not require as much leverage to push the oval ring as you sweep through the bottom of your stroke. It’s simply amplifying the “pulsing” of a natural pedal stroke. No one pedals in perfect circles. But the thing which is most confusing to everyone, is that you will actually feel that your stroke is more “round” with an oval shape than with a round chainring. This is something you can’t imagine and I can’t show on a website – you have to try it to believe it.
In other words, it is easier to make the same power, as the pedal stroke is smoother and you feel stronger in the dead part of the stroke. It uses mechanical advantage (lever, really) to allow less exertion = reduced torque, but more constant speed (instead of pumping/mashing). Humans are not machines, so they do not generate constant power and speed across whole revolution. Oval amplifies the power zone as humans can push there more and minimises dead zone as legs can’t put torque down when the crank is vertical.
Oval 32T fits best someone who currently uses round 30 or 32T. They will feel exactly the same on the oval one, but will be riding faster by pushing for a moment 34T in the oval’s biggest radius.
They also do not affect clutch mechs like many claim. Here is a proof:
They can be used in singlespeed therefore as chain tension does not change.
The 32t chainring retails for £46.99