AbsoluteBLACK Release World’s Smallest Oval Chainring

UK based bike brand AbsoluteBLACK have been responsible for some very clever drivetrain solutions since they opened for business back in 2008. We’ve reported on their chainrings, trick hubs, and their new oval-compatible chainguide, though chances are you’ll best know them for their intriguing oval-shaped 1x chainrings.

Designed in the UK, then machined in Poland using raw material from Germany and finally anodized back in the UK (their chainrings have travelled more than we have!), AbsoluteBlack chainrings are some of the trickest-looking around. They offer most chainring sizes in an oval version, which they say increases pedal efficiency by shrinking the effective chainring diameter through the ‘dead stroke’. What they haven’t been able to do up until now however, is offer a 30t oval chainring for standard 104 BCD cranksets. The 104 BCD size is one of the most common crankset mounting standards on the market, so there’s certainly a market for it.

So if it’s so hard to do, how have AbsoluteBLACK created the smallest 104 BCD oval chainring in the world?

The AbsoluteBLACK 30t oval chainring is the smallest 104 BCD compatible chainring in the world, and it’s taken some clever engineering to make it happen.

Press Release: The world’s first 30T 104bcd Oval chainring.

You might ask what is so special about that particular chainring? Until today, 32T was the smallest possible oval chainring that could fit and work effectively on 104bcd crank tabs. Small threaded standoffs on those rings spaced it out from the crank tabs, allowing the chain to fit freely for full link engagement.

The 30t oval 104 BCD chainring uses two conventional mounting holes, and two smaller holes that rely on offset hardware to match up with the tabs on the crankset.

The reason 32T was considered the smallest size oval ring you could fit to a 104bcd crank is because if made any smaller the normal M8 bolts used in the crank tab mounting holes would actually be positioned on the chainring teeth in smallest part of the oval preventing any engagement of the chain links. A 30T oval chainring on 104bcd cranks was not thought possible…

In today’s market 30T size is extremely important; it is a second most popular chainring after 32T among riders. Lack of this size in the most popular BCD dimension (104mm) on the market is far from ideal.

With modern 1x drivetrains, having a smaller front chainring offers you additional low-range gearing that’s ideal for 29in bikes and long-travel trail bikes.

AbsoluteBLACK however has found the solution to this problem. Its Patent Pending mounting system is incredibly simple, elegant and easy to fit. “We have been rigorously testing our 30T oval chainring solution for over seven months now, while applying for international patents. It’s a size riders keep asking us for every single day, so we had to come up with the solution, as I hate to say “not possible” to people…” says AbsoluteBLACK founder Marcin Golec.

The two mounting holes, closest to the tallest part of the oval, have regular M8 threaded standoffs – like you would find in the oval 32T ring. The other two holes in the shallow side – where space is limited and the M8 bolt fouling would normally occur, contain special eccentric M5 threaded standoffs. These slimmer M5 bolts, combined with special eccentric spacers ensure the new smaller 30T oval chainring can fit easily to any 104bcd crank tabs. It’s easier to understand looking at the photos.

The degree of ovality of the new 30T chainring is exactly the same as their direct mount equivalent in AbsoluteBLACK’s portfolio, which means no compromises to performance have been made in order to achieve proper fitting.

Entire new 30T 104bcd chainring set comprises of two regular M8x8mm aluminium bolts, two M5 steel bolts (like for disc rotors), two eccentric aluminium spacers and a chainring, of course. The weight for the 30T 104bcd chainring is only 36g and an additional 7g for hardware.

This image shows exactly what the challenge was for AbsoluteBLACK when designing the 30t oval 104 BCD chainring. The chain comes VERY close to the tabs on the crankarm, which is why the offset is required to provide the necessary clearance.

While talking about chainrings AbsoluteBLACK is also pointing out that their entire range of chainrings is also compatible with the new SRAM Eagle 12spd drivetrains. This is a response to a commonly asked question.

There is no need for special hooked tooth shape in order to get things working properly says AbsoluteBLACK founder Marcin. He continues “SRAM has marketed their new rings as the only ones that will work with Eagle chain and cassette. But fact is that the chain has changed only minimally in dimensions versus the 11 speed one and we already have done a small running adjustment (before Eagle became available) to our AbsoluteBLACK chainring tooth thickness to accommodate the changes to the new SRAM Eagle chain.”