Just before Eurobike we had a chance to visit the team behind new component company B|Labs in their headquarters at the base of the Bavarian Alps. One of the first things they were excited to show off was their new non-round/elliptical, narrow-wide single ring mountain bike chainring that they are calling B-ring OVAL. It wasn’t quite ready to ship then, so we’ve been keeping it under wraps, but now they have both 4-bolt and SRAM direct mount spider-less options available.

Hop past the fold for more details on the rings, sizing, pricing, and crankset compatibility, plus their upgraded chain retention device….

B-Labs_B-Ring_OVAL_elliptical_narrow-wide_mtb_chainring_front_complete B-Labs_B-Ring_OVAL_elliptical_narrow-wide_mtb_chainring_rear_complete

With the popularity growth of 1x drivetrains in enduro and all-around mountain riding, B-Labs saw an opportunity to develop an affordable alternative to a whole new groupset. Their OVAL ring is compatible with all 9, 10 & 11 speed mountain groups and will make a great upgrade to drop the front derailleur and save some weight and complexity when your current chainrings wear out.

Pulling one or two chainrings off the crank does have the downside of ending up with less gearing range, and usually means losing a couple of those easy hill-climbing gears. Elliptical ring shaping simulates a small regaining of that lost range, helping to limit losses. The shape of B-rings effectively adds 2 teeth above the ring size with the cranks around the most powerful ~2 and 8 o’clock positions, while effectively reducing by 2 teeth at the least powerful ~11 and 5 o’clock positions. That means the 32 tooth ring we sampled essentially pedals like a 30-28T range.

Also don’t forget that even though the rings aren’t round, they still wrap the same amount of chain in any position. So you don’t get fluctuating chain growth, making the rings single speed friendly. The elliptical shape could be great on a single speed, so we’ll see if we might be able to get ahold of one for a test.

B-Labs_B-Ring_OVAL_elliptical_narrow-wide_mtb_chainring_packaging B-Labs_B-Ring_OVAL_elliptical_narrow-wide_mtb_direct-mount_chainring_rendering
The B-ring OVALs are machined from 7075 aluminum with tall, alternating tooth profiles to securely engage the chain and limit chain drop. The rings are made with an asymmetric offset chain line, that aims to keep the rings as close to the chainstay as possible to limit noise and cassette wear in the easier cogs; and the 4-bolt rings have built-in chainring bolt threads too, so no need to buy special single ring bolts or spacers.
The standard 4-bolt rings that we saw are generally compatible with any of the typical 104BCD cranksets (see chain line details below) and are available in 32, 34, and 36 tooth options. So far we’ve only seen computer renderings of the direct mount rings designed to bolt onto SRAM GXP or BB30 removable spider cranksets, but the bolt-on solution lets B-Labs g0 further down to offer 28 and 30 tooth options for extra hill climbing power.

MSRP for the 4-bolt 104mm rings is $70/50€/£45, while the direct mount (SRAM) rings are $85/63€/£55. They can be purchased directly from Bionicon’s webstore or from Amazon. Follow links from the bottom of the OVAL rings page.

B-Labs_B-Ring_OVAL_elliptical_narrow-wide_cyclocross_110_compact_42T_chainring_rendering.jpg B-Labs_B-Ring_OVAL_elliptical_narrow-wide_cyclocross_110_compact_38T_chainring_rendering.jpg

One more interesting bit of news/rumor, when we were visiting in August we suggested to B-Labs about the potential for 1x oval cyclocross rings, as well. While it isn’t clear if they’ll be available immediately for current cross racing, B-Labs’ engineers were receptive to the idea and have since scaled their designs up to 110BCD and 38-44 tooth options. If that sounds good to you too, drop a line in the comments to let them see some reader interest. And we will hopefully get one to test as soon as they hit the ground.



Lastly, not to be missed in our visit with the B-Labs team was their simple, cheap, and effective chain retention device. Now in its third generation, the in-molded C.Guide simply zip ties to the chainstay to keep your chain wrapped on the chainring. Made up of a rigid upper plastic section that attaches to the stay, a flexible elastomer mid-section that pitches/twists/rolls to accommodate shifting from one chainring to the other or across the cassette, and a low-friction plastic lower section that snaps around the chain, it solves chain retention in an tidy 14g package.

B-Labs_C-Guide_Eco_mtb_chain_guide B-Labs_C-Guide_Eco_mtb_chain_guide_packaging_front B-Labs_C-Guide_Eco_mtb_chain_guide_packaging_rear

No rollers keeps it simple, and the elastomer is claimed to even damp the chain vibration that is often the cause of chain drop. The low-friction glide plate should last a couple of years and can even be flipped around to double its wear life. At just $30/28€ the C.Guide ECO looks like a good buy, and would complement the OVAL rings well without the need for a clutch rear derailleur. It is intended to be used with a max 36 tooth ring, but there was talk of some success on slightly larger cyclocross ring setups too. We’ll probably strap one on a bike in the spring here in Europe when we get back to some Enduro testing.

Although the B-Labs name is new to us, the people behind it have built a name for themselves as industry innovators over the past few years with their bike building business Bionicon. B-Labs was spun off as a component engineering arm of the bike company to allow them to develop some of their ideas and get them out to consumers independently of their unique bikes. With this in mind B-Labs has also developed a lightweight crank-based e-bike motor, and is continuing to develop some other interesting projects like suspension components and valving that will probably bring some of their Bionicon performance to the OEM and after market in the future. We’ll keep an eye on them and let you know when we hear anything new.



  1. Currently run a Rotor elliptical ring on my SS, would never go back to round rings. The chain does change tension depending where it is on the ring.

  2. “Elliptical ring shaping simulates a small regaining of that lost range, helping to limit losses. … the 32 tooth ring we sampled essentially pedals like a 30-28T range.”

    No it doesn’t. A full revolution of the crank results in 32T worth of chain just like any other 32T chainring. All it does it produce a lumpy cadence, it does not give you something for nothing. There is no such thing as free power, it all comes from your legs.

    The lower effective ratio through the dead zone means your pedal must speed up to maintain tension, when your legs are least capable of doing so, while the increased ratio in the power zone means more time is spent under load leaving less time for muscle recovery. This is why Biopace was oriented in the exact opposite fashion (and why elliptical rings are fool’s gold in the first place).

    …and like other elliptical rings promoted on this site recently, these rings have no provision for timing adjustment making them a crapshoot. Different riders and different bike fits need different timings. Manufacturers like this one don’t understand that since they’re just ripping other companies off.

    The BS on this site over elliptical rings recently is astounding.

  3. I recall back in the early days when bio-pace was shouted as the great innovation only to be discontinued due to lack of evedence showing any real gain.. do many vairables in riding mtb’s for me to see any gain what so ever… they look pretty though, that chain retention is similar to whats on my genius LT, there light, work well and I don’t notice any increase in chain drag…

  4. @Aaron I use a 40 tooth 130 BCD Doval Chainring in my CX bike SNW (it’s narrow wide in just a side) I think that they also offer NW chainrings for that BCD.

  5. Probably wouldn’t be great because it can’t move at all to take up slack from the chain. You’d still have to size the chain just right.

  6. @ craigsj…sorry, experience trumps [your] theory. Try riding them some time. With comments like “All it does it produce a lumpy cadence,” it’s clear that you haven’t. After you ride non-circular rings for a while, switching to round rings produces a lumpy cadence, too. You adapt, either way. While I don’t think non-circular rings give you free power, they definitely keep the legs fresher on long rides.

    I agree that these rings should have timing adjustment, but it’s not a “crapshoot” without it…it’s just not optimal for everyone.

  7. buriedundersnow – 10/31/14 – 10:04am
    “Yo B-Labs – will the C-Guide work in theory as a SS tensioner?

    I am also interested in the answer.
    I have a tandem. Both chains are SS-width.
    Will the C-Guide fit them?

  8. @buried @Menos the C.Guide isn’t likely to help with SS setup. It doesn’t really tension the chain just provides a little more wrap around the chainring. Plus, I seriously doubt that you’d want you chain tension relying on the 2 small zipties that hold this thing to the stay.

  9. Oval chainrings are somewhat making a minor comeback only because of people too young to remember they were a fad in the 80s before everyone, yes everyone realized they were useless.

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