What's Cool In Road Cycling

Absolute Black Oval Chainrings Review

Chuck Peña got his hands on some Absolute Black Oval chainrings to give them a good going over, inspired by Chris Froome’s wins at the Tour and Vuelta using oval chainrings. But with mixed views on their functionality, we asked what are they like to ride? Here are his findings.

absolute black oval chainring

A little back story before I begin. I originally bought Absolute Black oval chainrings for my wife’s bike last spring because she has a history of knee issues and everything I’d read about oval chainrings and different user reviews indicated they would likely ease the strain on her knees. Rotor Q rings were an obvious choice and I knew about Osymetric oval rings, but I decided to try new kid on the block Absolute Black – who claim to be the largest mountain bike oval chainring manufacturer in the world, but are a relative newcomer to road bikes – because… well… their chainrings just look badass!

absolute black oval chainring domane
Absolute Black in black on my wife’s Domane

Fast forward a year of happy riding by my wife and Tony Brand at Absolute Black hooked me up with a set of rings to review for PEZ. Thank you, Tony!

absolute black oval chainring packaging
Fancy packaging

Yes, I know the purists will scoff at the idea of oval chainrings. And there will be the inevitable claim that they are just Shimano’s ill-fated Biopace resurrected. But none other than 4-time Tour de France winner Chris Froome – also only the third rider to win the Tour-Vuelta double – rides on oval chainrings (as did Bradley Wiggins when he won the Tour). So maybe there’s something to oval chainrings? Well, the only way to know was to give them a try.

To begin, Absolute Black oval chainrings are NOT gussied up Biopace chainrings. And for the record: I rode Biopace way back in the day. Both the ovalicity and timing of Absolute Black chainrings are different – not just from Biopace, but also from their competitors. But Absolute Black doesn’t provide exact figures about timing and ovalicity, as that is Patent Pending intellectual property.

The theory behind oval chainrings is that they maximize the part of the pedal stroke where power is produced and minimize resistance where it isn’t based on the assumption that the musculature of human legs makes it difficult to maintain an even power delivery with a round chainring. I won’t get into a debate about the science of oval chainrings and whether they’re actually better than round chainrings, our Dr. Stephen Cheung examined Chain Rings And Power Output, and took a closer look at Rotor Rings here, but there are at least two other studies that provide evidence that they are:  Effects of Chainring Type (Circular vs. Rotor Q-Ring) on 1km Time Trial Performance Over Six Weeks in Competitive Cyclists and Triathletes (September 2011) and Physiological Responses during Cycling With Oval Chainrings (Q-Ring) and Circular Chainrings (May 2014).

I’ll also be upfront and state at the outset that my review is strictly subjective based on actual road riding. I don’t have a lab with identical bikes and all the necessary gizmos – such as left/right power meter and Cyclologic/Motion Metriq sensors – to be able to take measurements, collect relevant data, and do any sort of quantitative analysis and comparison.

The first thing you notice about Absolute Black oval chainrings is that they aren’t round!

absolute black oval chainring inner
Round vs. oval – Ultegra 36T and Absolute Black 36T small chainrings

absolute black oval chainring inner
But the difference between round and oval small 36T chainrings isn’t so drastic

absolute black oval chainring vs ultegra
Round vs. oval – Ultegra 50T and Absolute Black 50T big chainrings

absolute black oval chainring vs ultegra
The difference between round and oval is more noticeable with the 50T big chainrings

Changing out my Ultegra chainrings for the Absolute Black chainrings wasn’t hard but also wasn’t a simple, straightforward affair. Because of the design of the Ultegra crankset and chainrings, I had to remove the crankset to get the chainrings off. With a more conventional 5-arm crank spider with external bolts, it’s probably possible swap chainrings without having to remove the crank.

Installing the Absolute Black chainrings requires paying attention to the instructions to orient them properly on the crankset so the timing of the ovalicity is correct. The small inner chainring is mounted with the triangular timing indicator positioned behind the crank arm. The big outer chainring has a recess that is lined up with the crank arm. Once those are properly lined up, just insert and tighten the four T-30 torx bolts.

Because of the Ultegra 6800 “covered” crankset design, I couldn’t re-use the original chainring bolts (the same holds true for Dura Ace 9000). Instead, I had to use Absolute Black long chainring bolts, which are needed whenever you replace both chainrings on any type of crank: 110/4, 110/5, or 130/5 BCD.

I also had the option of either a more “industrial” look with exposed chainring bolts or using Absolute Black crank bolt covers for a sleeker OEM look. I haven’t yet decided which look I like better. I welcome feedback from PEZ readers.

absolute black oval chainring
“Naked” chainring bolts

absolute black oval chainring
OEM look with Absolute Black crank bolt covers

And then there’s having to re-adjust the front derailleur. Changing from a round to oval (any oval) big chainring will require raising the front derailleur to accommodate the eccentricity of the chainring. I essentially “re-installed” the front derailleur as if I was doing a bike build. So a bit of fiddling to get the derailleur lined up properly, setting the high and low limits, and fine tuning the cable tension in the trim position. I also had to re-adjust my K-Edge chain catcher.

OK, so how do they ride???

First and foremost, the pedal stroke feels perfectly normal. Yes, it’s a little different than with round chainrings. But not so different that you really notice or feel it. It would actually be interesting to do a true blind test with riders (on trainers, not on the road!) to see if they could tell the difference between round and Absolute Black oval chainrings if they didn’t know and couldn’t see which chainrings they were riding. That the pedal stroke feels normal makes sense if the theory of oval chainrings is right, i.e., that they, in effect, smooth out the pedal stroke (for what it’s worth, I’ve been told that I have a pretty smooth pedal stroke so it’s not like I was looking for something to smooth it out) by minimizing resistance during the “dead spot” of the pedal stroke. It’s also a testament to Absolute Black getting the ovalicity and timing of their chainrings right.

It’s worth stating something obvious: with oval chainrings you still pedal in circles. After all, the cranks are still spinning on a round axle. What’s different is how the chainring moves the chain. I could witness this phenomena when I could see my shadow when riding. My feet were moving in a circle but you could see ovalicity in the rotation of the chainrings. It was like an ah-ha! moment.

absolute black oval chainring riding

If you are a high cadence spinner, you won’t have any problems spinning on Absolute Black oval chainrings. That shouldn’t come as a big surprise if you’ve seen Chris Froome riding on oval chainrings – his legs can churn like a blender. I don’t consider myself a high cadence rider by nature, but when I was in a “groove” and not having to “fight” to put down power, I could ride at a steady 100-110rpm for extended periods. And just for grins, I was able to smoothly spin at 130-140rpm for short stints – but I would eventually “spin out” just as I would if I were riding round chainrings.

The sensation I felt riding Absolute Black oval chainrings was that I was putting down power with less effort. Of course, without the ability to actually measure and compare to round chainrings, I can’t confirm that this is actually the case. But that’s what it felt like. And it was probably more pronounced at slightly lower cadences, i.e., 80-90rpm. I’d often find myself thinking I was being “lazy” because my cadence didn’t feel all that high and I didn’t feel like I was working that hard – only to look at my Garmin and realize I was going faster than I thought! So I could see how using Absolute Black oval chainrings would be a benefit to relatively steady-state efforts such as time trials. Not that it’s definitive proof, but Chris Froome is a pretty good time trialist and rides oval chainrings!

Absolute Black claim “oval rings enhance a cyclist’s ability to spin with a smoother power delivery and feel easier on legs while climbing” and that they allow a rider “to achieve higher average speed riding uphill.” Again, I can’t definitively say this is true. Riding uphill is always work and never easy, but the sensation I had with Absolute Black oval chainrings was one of less perceived effort while climbing. What I haven’t had a chance to do (and it will have to wait until next riding season) is do a ride like Skyline Drive that has 4-6 mile climbs with gradient of 5-8 percent that are all about seated climbing to see if Absolute Black oval chainrings are “easier” or “faster” – I’d be more than happy with the former and the latter would just be a welcome bonus.

absolute black oval chainring

Where I did notice a real difference between round and oval chainrings was (a) the transition from seated to out-of-the-saddle and (b) out-of-the-saddle climbing. The transition is very fluid. There’s often a feeling of “hesitation” as you get out of the saddle and I didn’t feel that with the Absolute Black oval chainrings. It just felt like I was maintaining forward momentum. And climbing out-of-the-saddle just felt smoother and easier with oval chainrings. This makes intuitive sense since standing accentuates both the power and non-power phases of the pedal stroke, which oval chainrings are supposed to smooth out. So instead of the pedal stroke feeling like a down-up action like pistons, it actually feels more “round.” Or put another way, pedaling while standing feels a little less “jerky” and more “continuous.”

Not only does out-of-the-saddle climbing feel smoother with Absolute Black oval chainrings, but it also feels easier. Whenever I got out of the saddle to climb (especially up some steeper pitches – including one short climb that is 14 percent average gradient), it felt like it required less effort. Especially doing some big ring climbs. I’m not talking a night and day difference, mind you. But enough of a difference – however small – to notice.

absolute black oval chainring ramps

At least for me, it’s almost as if the Absolute Black oval chainrings encourage me to get out of the saddle on climbs. So I guess I’ll be doing my best Alberto Contador impersonations more often.

I know that one of the potential bugaboos with oval chainrings is shifting. Absolute Black address this issue with six shifting ramps machined on the backside of the big chainring. My experience was that shifting from the small to big ring was as crisp and as fast as with my stock Ultegra round chainrings. And no issues going from big to small – as long as your front derailleur is properly adjusted, you shouldn’t have to worry about dropping your chain.  To find more bike parts and accessories, check out carbibles.com that will help you to choose the perfect ones for your bike.

absolute black oval chainring inside
Up-shift ramps on the back of the chainring help the chain make the move to the big ring

Here is what my intuition (based just on riding without any measurements or data) tells me about Absolute Black oval chainrings: the actual benefit is probably relatively small in an “absolute” (no pun intended) sense. But it does feel like there’s a benefit and that benefit is likely cumulative over time – pedal stroke after pedal stroke. Whether it’s reduced stress or less muscle fatigue, it’s likely to add up over the course of a ride – where thousands, if not tens of thousands, of pedal strokes are involved. So a truly marginal gain – even if relatively minuscule – that adds up.

Everyone who knows me knows that I’m not a big Chris Froome fan (but I certainly respect him and his accomplishments), so they won’t believe I’m going to say this: I’m going to be like Froome and go oval.

absolute black oval chainring
Once you go Absolute Black, you may never go back … to round

PEZ contributor Chuck Peña is a former weekend warrior racer who now just rides for fun, but every once in a while manages to prove Fausto Coppi’s adage true: Age and treachery will overcome youth and skill. He lives in Arlington, VA with his wife (who is his most frequent riding partner), his daughter (an aspiring junior golfer who takes great joy in beating him all the time), and their dogs. You can follow him on Twitter @gofastchuck

Note: if you have other experiences with gear, or something to add, drop us a line. We don’t claim to know everything (we just imply it at times). Give us a pat on the back if you like the reviews, or a slap in the head if you feel the need!

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