Oval chainrings are becoming increasingly commonplace on pro peloton bikes. From Chris Froome, to Bradley Wiggins (for a time); the asymmetric profile of their chainrings is apparent. But, what are the advantages of oval chainrings? We test the Q-rings from Rotor, to see if we can find out…
The problem with any testing of marginal-gain variables, is that they are just that; marginal. There are numerous other factors that could affect the outcome of a training session or race; so just fitting a set of Rotor Q-Rings to you bike, and seeing if you ride faster, isn't going to be very accurate.
To make the comparison of Rotor Q-Rings to my normal chainset, I fitted them to my winter training bike; with the same large chainring size (52T) on both. Before doing this though, I rode the same out-and-back route along a rolling (big ring only) road, at the same wattage, for four Saturdays in a row. Then, having fitted the Array, I repeated the test route another four times, and used a Garmin Edge to gauge the effect that the oval chainrings had on my average perceived effort, cadence, heart rate and speed (at the same wattage).
So, what were the results?
The moment you start using oval chainrings, you notice the difference. The Array I fitted wasn't even that severe in its asymmetry; yet it had a noticeable effect…
The feeling when you shift up into the asymmetric large ring (I kept a normal inner chainring for comparison), is somewhat similar to the feeling of having a slow puncture; a sort of micro-surging of the bike underneath you. Within a few minutes though, you become accustom to it, and your pedal stroke adapts; creating what then actually feels like a smoother overall motion.
Did it make me faster?
For me, not noticeably faster as such, no. BUT, it did have two positive effects…
The first notable effect using the oval Rotor Q Chainring, was that my average cadence increased. I have a tendency to drop my cadence when I tire, and I attribute the higher cadence on all four of the Q-ring rides, to being related to this trait. I reckon that by effectively reducing the resistance during the weakest part of your pedal stroke, you allow yourself to pedal faster; because that weaker part is slower to rotate-through on normal rings, just like your overall pedal stroke is slower when you are more tired/weakened by prolonged effort.
The second effect was less obvious, but still apparent: my average heart rate (for the same wattage) was slightly lower. I attribute this to a similar explanation as the higher cadence; in terms of making your pedal stroke effort more constant. Ultimately though, the change in heart rate for the same wattage signals greater overall efficiency.
The overall effect was therefore positive. The Rotor Q-rings seemed to lead to a more efficient, less tiring pedal stroke.
Cause and effect?
As mentioned, it is hard to attribute these two positive effects decisively to the Rotor Q-rings; there are too many other variables. However, they are two of the results seen by most riders who make the change; and notably by riders who are likely to see the marginal improvements, such as time-triallists.
Worth the change?
Oval chainrings appear to have potential positive advantages; and no notable negative effects, other than perhaps an increased tendency for dropping the chain on the front derailleur down-shift (normally when you are cross-chaining on the cassette to a significant extent).
Rotor's Q chainrings could make you more efficient therefore, and reduce fatigue. Certainly the positive effects they have had on my cadence and heart rate, mean that they have stayed on my bike for further testing in training and racing.