Absolute Black Oval Chainring

Oval chainrings have been making solid inroads into the MTB scene over the last year or two. Claimed benefits over non-round rings vary from maker to maker, and range from better efficiency, to less fatigue, to more power, to smoother power delivery.

For the past 12 months I’ve been using a round Absolute Black narrow/wide ring, so I swapped it for the oval version see what it was like. At 55g the 30-tooth SRAM direct mount ring is pretty much bang on the claimed weight and prices vary from around $85 to $105 depending on mounting configuration.

First up, let’s just dispel the ghosts of oval chainrings past; the ovalisation, or ‘clocking’ of modern oval chainrings is exactly the opposite of the diabolical ‘Biopace’ rings that Shimano tried a few decades back. Now, the harder gearing becomes harder on the downstroke where your legs have the most power, and the smaller diameter is in your dead band where the cranks are moving horizontally. This means that our 30-tooth ring is like a 32T when your legs are at their strongest, and a 28T when they’re at their weakest. It seems pretty logical really, and how anyone ever thought the opposite was a good idea is beyond me.

The construction quality of Absolute Black chainrings has always been top notch and this puppy is no exception. The CNC work is truly beautiful and the weight is competitive too. Fitting a direct mount ring is as simple as removing the cranks, undoing the three Torx mounting bolts and reversing the process with the new ring in place. On this relatively small ring the ovalisation is visibly pronounced. While the elliptic effect will feel similar on a bigger ring, its dimensions will look more normal.

I run a minimalist top guide with my 1x11 setup and the variation in chainring radius meant that it took a little longer to get the position sorted. At the small radius points there will be more gap above the chain than you’d normally run; it still performed reliably for me but there may be a small compromise in chain security. While the diameter of the chainring wavers up and down, the effective chain length hardly changes. As a result, the oval chainrings will work in most single speed applications, although you may encounter problems if your SS setup is particularly finicky (see below for an example). 

My first pedal around the street felt odd and the variation in effort around the pedal stroke was definitely noticeable. However, I’d completely forgotten about it after a few minutes on the trail. Whether this is because my body had adapted to the new setup, or because the uneven trail surface provided ample distraction is impossible to say; somehow I think it’s a combination of the two. In any case, the oval ring felt particularly ‘normal’ after those first few minutes—if you're expecting a non-round ring to feel hugely different, in either a good or bad way, you're in for a disappointment.

Oval Spin
Most of the oval ring zealots will tell you that after a month or so on an elliptical setup, switching back to a round ring will feel lumpy and horrible to pedal, so that’s exactly what I did. I will say that the power transfer didn’t feel as consistent when pedalling a flat and smooth surface, but again was essentially unnoticeable in real trail conditions. It’s worth noting that I ride flat pedals, where all pedalling effort goes into pushing down to turn the cranks. In contrast, our editor has ridden clipped in for the past 25 years and prefers to spin at a higher cadence. For him the round ring felt smoother when pedalling along the flat but the oval ring was preferable when climbing. He too quickly forgot about it on the dirt as there more important stuff to focus on — like tree avoidance. If anything can be drawn from this, it’s that oval rings may be more beneficial to those who grind whilst high cadence spinners mightn’t be as keen to adopt the egg-style rings.

Does the oval shape provide smoother power delivery to the ground and better traction on loose climbs as the marketing hype states? Logically it makes sense but personally I feel there are too many variables (weight distribution/line choice/crank clearance not to mention random luck), so I can’t categorically state there was a significant improvement. I certainly didn’t find myself floating up every challenging climb that previously stymied me.

Are they more efficient and did I finish feeling fresher after every ride with the oval ring? Again, there are just too many variables in the human ‘machine’ for me to make that claim. You’ll even find conflicting results within the independent lab testing that’s been done on oval rings, with some indicating a measurable improvement and others showing negligible gains.

The concept certainly makes sense; a bigger gear where your legs have the greatest mechanical advantage yet easier to pedal through the dead spot. As much as we don’t think they're a total game-changer for the average rider, we also don’t see any disadvantage with using them. They certainly wound up being our preferred option, especially when it came to steep or sustained climbs. So in this context I feel they are definitely worth a try, especially if you’re oval-curious.

 

Single Speed Setups

While most of our testing was done with a 1x11 equipped dually, we also tried the Absolute Black oval chainring on a single speed hardtail. While the chain obviously moves up and down along with the elliptical chainring, the actual chain tension remains fairly consistent. With the narrow/wide teeth and a SS specific rear cog, we didn’t have any problems with chain loss on this bike.

Distributor: SCV Imports (02) 4353 2633
www.scvimports.com.au