Oval (elliptical) chainrings continue to gain in popularity, having been spotted on bikes belonging to pros like Chris Froome and other elite athletes. Simultaneously, many cyclocross and gravel bikes are abandoning double cranksets and front derailleurs in favor of lighter, simpler, "1x" drivetrains, based around a single chainring.
If you're taking the plunge and moving to a 1x setup, should you also consider making that new chainring an oval? Yes! Let's talk about why.
Oval chainrings use an elliptical (non-round) shape. The stock rings that came on your bike are very likely perfectly round. Oval rings are shaped more like an egg.
Today's oval chainrings have nothing to do with Shimano's "Biopace" rings from the 1980's. Biopace rings actually had the exact opposite design compared with modern oval rings - they made pedaling too difficult in the dead zone and too easy in the power zone.
When riding a bicycle, you can't produce a consistent power output throughout the rotation of the pedals. You have "dead spots". By varying in diameter, oval rings change the amount of leverage - increasing your pedaling effectiveness. You can push harder and reduce fatigue.
Of particular note for cyclocross riders: oval chainrings can help improve traction on steep, loose, slippery climbs where you struggle to maintain grip.
Switching to a single chainring drivetrain has some key benefits:
You still see double chainrings, especially at the elite levels. Those riders can turn a 46 tooth ring and benefit from (and need) a wide-range double drivetrain. If you aren't good enough to race in Europe, however, a 1x setup can work great for you.
Popular brands include Wolf Tooth, AbsoluteBLACK, Ride1Up, and others. When considering a chainring purchase, look for compatibility with your crankset and drivetrain. You'll also want a chainring that uses a "narrow-wide" tooth design to help retain the chain, since you no longer have a front derailleur.
There are a few things to know:
If you're not riding a 1x drivetrain yet but are considering switching, an oval ring is a no-brainer. Kill two birds with one stone and make the jump to oval at the same time you go 1x.
Want to stick with a traditional double chainring drivetrain? The decision is less clear. While oval chainrings are available in double chainring configurations also, nothing shifts as well with a front derailleur than Shimano's stock rings.