Review: B-Labs B-Ring OVAL Chainring

Oval chainrings are not a new invention. Those that have been in the sport long enough will likely remember Shimano’s Bio-Pace chainring, and possibly even shudder. It’s important to note up front that the B-Ring OVAL chainring is not a distant relative of the Bio-Pace. But just as with bell bottoms, many fashionable items will come full circle, fading from memory before being revived again.

The difference between bell bottoms and oval chainrings, though, is that the mountain biking industry has evolved a great deal since the last oval chainring revolution. The current transition to 1x for 9/10/11 drivetrains is a real advantage for oval chainrings, as the integration of multiple oval chainrings in the front cassette can lead to horrible shifting issues. But a 1x system is where these oval chainrings can shine, especially the chainrings by B-Labs.


Oval Chainring Benefits from B-Labs:

Though some of the features that B-Labs claims for the oval chainring are actually just benefits found when switching to a 1x system, the B-Ring OVAL does offer some unique features.

Virtual gear range – roadies, triathletes and XC racers have long known about the benefits of using oval-shaped chainrings. Its elliptical shape provides you more torque at your weak-spot of the crank position. This means, that it virtually gives you -2 teeth lighter gears in your crank weak-spot and +2 teeth harder gears in your sweet-spot.

Increased pedal efficiency isn’t the only reason to switch to the B-Ring OVAL chainring. It also sports the narrow-wide design to increase chain retention without the need of a clutch derailleur or even a bottom bracket chain guide. Additionally, the B-Ring OVAL has an off-set chain line, which B-Labs claims is a narrower chain line than other 1X chainrings. This will reduce friction and wear on your drivetrain.

Details from B-Labs:

  • Alternating tooth profile for ultimate chain retention
  • Virtual range – elliptical shape simulates -2 / + 2 teeth as you ride
  • Offset chain line – mounting position optimized for 2- or 3-ring cranks
  • Direct thread mount – no more 2-part chainring bolts or bloody knuckles!
  • High-strength 7075-T6 Aluminium alloy
  • Black anodized
  • Laser finish
B-Labs offers a whole host of configurations for compatability with just about any drivetrain. Photo by: B-Labs
B-Labs offers a whole host of configurations for compatibility with just about any drivetrain. Photo by: B-Labs

Out of the Boxletter

The first impression is one of a minimalistic and clean design. The chainring comes packaged in a sleek holder with even a letter to the new, happy owner, describing the quality and craftsmanship of the chainring. Though other competitors offer a variety of finish color options, B-Labs does not. I’m bad about keeping my drivetrain clean anyhow, so even a neon pink chainring will end up black. However, I did find that the black anodized finish was sharp.

B-Labs claims that a 32T BCD104 will come in weighing 40g. My very unscientific kitchen scale weighed in on the skinny side of 34g. Perhaps my kitchen scale runs on the low side. Now if only my bathroom scale would do the same.

The B-Ring OVAL chainring weighed in less than claimed on B-Labs website. A very important note for all the weight weenies.
The B-Ring OVAL chainring weighed in less than claimed on B-Labs website. A very important note for all the weight weenies.


The chainring installation is a breeze. I simply removed the crank, took my existing 30T chainring off, and switched it out for the new one. There are brands that recommend adding links to the chain to compensate for the ovality of the chainring. However, that is not necessarily the case for the B-Labs design. I ran my chain exactly as it was setup for the standard 30T and did not have any issues with it.

Test Ride out on the Trail

The B-Ring OVAL chainring is a fantastic upgrade for your 1X drivetrain.
The B-Ring OVAL chainring is a fantastic upgrade for your 1X drivetrain.

I’ll be honest, I didn’t expect to see a significant difference between the standard chainring and the oval chainring. As Jeff Barber spoke about in his review of a competitor’s oval chainring, there has been very little scientific evidence that indicates an oval chainring will actually increase your power output. With that said, training more and drinking less beer could probably increase my power output more than any upgrade I could buy. But that’s a rant for a different article.

I was surprised at how natural the oval chainring felt from the very first pedal stroke. I anticipated a transition period to become accustomed to the new design. However, as B-Labs touts on their website, the oval chainring results in a much more natural pedal stroke due to the fact that we as humans don’t tend to move in perfectly circular motions. Very rarely did I feel the ovality of the chainring; I was only reminded of the oddly-shaped chainring when either in too low or high of a gear.Chainring

I was most impressed on the trail by the way the B-Ring OVAL seemingly kept tension on the chain through the entire pedal stroke. The oval design performed as though I had maximum power available at all times. It also felt as though I had increased power capability when clearing technical sections that required a little bit more “English.” Bad form when pedaling can result in a preferential power stroke when only the leading foot is applying downward force, almost like stomping through the pedal stroke. You can highlight this effect by pedaling with only one foot. Proper form requires a push-pull action with both legs engaged at the same time. The B-Ring OVAL resulted in a more fluid, constant pedaling motion even with bad form, and it really shone with proper form.

Final Thoughts

The B-Ring OVAL chainring far exceeded my expectations. In all honesty, I didn’t expect this chainring to improve my pedal stroke as much as it did, and I’m currently planning to transition all of my mountain bikes to 1x systems with this chainring. My only recommendation is to keep the same number of teeth that you currently run. I’ve read a fair number of recommendations online that suggest moving up from say, a 30T to a 32T. However, I strongly advise against this unless you are already considering to upgrade to a 32T.

Careful, though, with transitioning to the B-Ring OVAL chainring, as you will quickly want to upgrade all of your bikes.


  • Sram Direct mount in GXP or PF/BB30: $84.95
  • 104BCD: $69.95
  • 110BCD: $89.95

A big thanks to B-Labs for providing the B-Ring OVAL chainring for review!