The first impression from riding the oval chain-rings is that pedaling feels much smoother, which is exactly the opposite of what I expected. It is true there needs to be some adjusting, but my perception is that the ovality of the rings almost forces the pedaling circle to be ‘rounder’ and therefore more efficient – thumbs up. I felt stronger, which is a second perceived benefit from using the rings.
The idea behind non-circular rings is that it maximizes the part of the pedaling circle where most power is produced (larger part of the ring = using a large ring) and minimizes effort on the dead-spot part of the pedaling circle (smaller part of the ring = similar to using a smaller ring). In the example below a picture of a 52T non-circular chain-ring ranging in size between that of a 48T to that of a 56T (correspondence will depend on the degree of ovality). Knowing that and having experimenting it, it makes me wonder why isn’t everyone around using them. There could be some drawbacks, I have seen cases where adaption to the front derailleur was necessary, therefore the installation and shift tuning does not seem completely agreeable with every single set-up out there. Also, a major drawback is the price, a set of new rings could easily cost in excess of USD 280, although with the increased popularity there are newer brands at more affordable prices.
BENEFITS: more efficient pedaling (lower oxygen consumption, lower lactic acid build-up, lower heart heart); angle customization (in some models)
DRAWBACK: disbursement on new rings; seamless shift tuning might be difficult or even require adaption of the front derailleur in some cases
THE MOST WELL-KNOWN TOUR BRANDS
Osymetric USA (http://www.osymetricusa.com/) – claims power gains of 7 to 10% in watts and 10% reduction in lactic acid build-up. The site brings a few studies comparing round to non-round rings in terms of: aerobic metabolism, hill climbing, power and others. Retail suggested price on Osymmetric´s site is USD 149.99 for an Outer 52 teeth ring and USD 139.99 for an inner ring (38 teeth).
ROTOR Bike Components (http://rotorbike.com/) – The Spanish company launched its oval Q-rings in 2005. According to the company they seek ultralight weight products with balanced rigidity. Rotor affirms QXL model tests show 1.6sec gain in a 1km TT by elite rider, compared to a gain of 1.6 to 1.8sec of 60mm aero wheels. Besides the ovality of the ring customization is possible via OCP (optimum chainring position) to 4 different settings, to better suit each riders style and riding situations. Prices on R&A Cycles range between USD 149 to USD 188 for an outer ring and around USD 90 for an inner ring.
A LITTLE HISTORY
Ogival, Le Plateau de Bernard Hinault, was made especially famous after rider Mass van Beek beat the world hour record using a 70 teeth ring, according to ovalchainrings.com (http://www.ovalchainrings.com/index.html). The radical ‘eye’ shape is noticeable from a far and will certainly make a conversation topic in the group rides. The site of the brand (http://www.ogivalring.com/) has some interesting videos in French, I was impressed with the ‘Les Plateaux Ovalises à la Loupe’ where the smoothness of the circular motion is demonstrated for the Ogival against other non-circular rings (Biopace Shimano, Polchlopeck, harmonic, and Stern). A single road ring on their site goes from around EUR 70 to EUR 117.
Doval – this is a Korean brand (www.doval.me) which offers a series of models for MTB and speed, road and aero, and include a MicroOCP with 5 tuning stages, being 1 with the lowest riding inertia (similar increasing the angle of the saddle), and 5 with the highest riding inertia (similar to reducing saddle angle – similar to triathlon and TT positions – recruiting posterior leg muscles). At Amazon UK website a pair will sell for GBP 99 and on eBay I have found a single ring for about EUR 30. This is the brand I bought and currently use, mainly because of affordability. I first used a pair of 52\39 which I mounted on my TT bike and recently swapped for a 54\40 pair.
Absolute Black – (http://www.absoluteblack.cc/) They offer a wide range of MTB and road chainrings starting at around USD 55. The aero 50T chainring will set you back USD 165.
Dual-Oval– (www.dual-oval.com) French designed non-circular chain-rings with 3 stages micro OCP settings. Regular price for a kit is around EUR 115 on the company’s website.
Proval Bike Components – brand of recordist time-trialist Maas van Beek. (http://eng.provalbike.com/). Have not found much pricing and availability information, although there are distributors listed. The company advertises outer rings as large as 54T with a 25% ovality which yields an equivalent to a circular ring of more than 60T.
Chain Reaction Cycles put the Absolute Black MTB chainring to the test:
As always, GCN has a good video about everything regarding cycling: