Oval Chainrings Could Reduce Knee Pain, if You’re a Masher
The cycling world is largely divided into mashers and spinners. When I was a kid watching the pros, this dichotomy just increased the rivalry and contrast of Lance Armstrong and Jan Ullrich. Ullrich was the diesel masher, an Indurain type. 80 rpm all day, flattening mountains. Armstrong was the spinner, floating away at 110 rpm and lifting himself into the clouds. Only one of those riders would have seen a benefit with oval chainrings.
Many of us, myself included, are drawn to oval rings by their marketing about reducing knee injuries and increasing power. I’m going to leave off the increasing power portion for now and dive into the knee pain section. Cyclists largely develop power from three joints, the hip, knee, and ankle. The amount of power developed from a joint has a direct effect on the amount of strain that joint experiences. Compression and shearing forces increase as joint power increases. This is one of the reasons that knee injuries are more common than ankle injuries while cycling, the ankle isn’t developing much power while the knee is. Oval chainrings change that balance.
Back in 2014, the journal Sports Biomechanics published an article digging into the kinematics of oval chainrings and came up with some quite interesting results. They tested 14 experienced cyclists at two powers (180 and 300), at three cadences (70, 90, and 110) and on three chainrings (Dura Ace circular, Rotor Q, and Osymetric). They used a myriad of sensors and a half-dozen cameras to analyze what the riders were doing, then scienced the crap out of the data they collected. The team pulled together some interesting results, especially at lower cadences.
The researchers used three different chainrings to understand the affects of increasing ovality, with the circle being the least oval, the osymetric the most, and the Q ring in the middle. Their results clearly show the ovality effects at the knee. Increasing ovality caused decreasing knee joint power, at lower cadences. This is potentially huge for people with osteoarthritic knees or knees that are prone to injury. At 70 and 90 rpm, both the Q ring and the Osymetric ring reduced the power at the knee and increased it at the hip, redistributing the joint forces in the system.
Moving the joint power up from the knee to the hip could decrease knee pain and injury over time. Because muscle contraction causes compression and shearing forces at joints, reduced muscle contraction strength reduces those forces. Since the knee is a more vulnerable joint in the pedaling system than the hip, shifting the burden of work to the hip could preserve knees for a few more years.
There is a caveat here though, with the Q rings. The study showed that knee joint power is decreased at low cadences with both Osymetric and Q rings, but actually goes up with Q rings at high cadences (the 110 state). That’s why Ullrich would probably have benefited from these more than Armstrong. Most non World Tour cyclists have a comfortable cadence in the 85–95 range, so both Q and Osymetric could provide knee preserving benefits for the vast majority of us. But if you normally pedal like Chris Froome attacking, Osymetric may be your best bet.
Is Less Better?
The question that remains then is simple: is less joint power at the knee better? And the answer is…. maybe. It’s certainly better for knee compression forces, but is it better for power output? This study doesn’t really delve into that beyond a bit of speculation. What it does show is if you’re having knee compression pain, oval chainrings may be a good intervention (after getting a bike fit). And if you’re having hip compression pain, oval probably isn’t for you. Keep spinning circles.
Luke is a cycling coach and physiologist from Richmond, VA who rides and races bikes all over the country. He’s an expert on the body in motion and its response to exercise and loves to share his knowledge with others. Find him @LukeHollomon everywhere.
