Despite the odd flirtation by the likes of Shimano over the past 30 years, one area of bike technology that has remained largely unchanged is chainring design, which traditionally uses circular chainrings to drive the chain and turn the rear wheel.
Yet some researchers have recently claimed that elliptical chainrings are better suited to the biomechanical requirements of pedalling, delivering more force to the crank for less perceived effort.
Some earlier research into ovalised chainring design did show benefits. In one study, 10 cyclists cycled with ovalised then circular chainrings at 180 watts, at both 65 and 90rpm, while having their crank torque profiles measured. Although the profiles were similar, blood lactate concentration (a measure of fatigue) was lower with the ovalised rings.
Chris Froome may be a convert to ovalised rings, but many remain unconvinced. A new study (J Sports Sci Med, May 2014) also suggests caution. In it 12 elite male cyclists performed two incremental cycling tests separated by 48hrs, one with round and one with ovalised chainrings. The workload increased by 25 watts every 3mins until the point of exhaustion. After the incremental test, four 20sec maximal sprints with 60sec recovery periods were performed. Heart rates, power outputs, oxygen consumption and blood lactate levels were monitored throughout.
During the sprints, average power output increased with the ovalised rings, but the gains were not large enough to be considered statistically significant. There were also no significant differences in blood lactate power output, oxygen consumption or HR between the oval Q-rings and conventional chainrings.
Do you find oval chainrings beneficial? Let us know in the comments below!