Words by: Liam Woods
It is no secret that oval chainrings have been a controversial topic ever since they came out. From the old school, bio-pace rings to the new and highly advanced oval chainrings from brands such as Absolute Black. The amount of testing and development the team at Absolute Black put into their products is simply mind-blowing and it can be seen in the quality of their products. You might be saying to yourself, well that’s great and all but I can’t run any tests, I don’t have an oxygen monitor, power meter, and near perfect trail conditions to get accurate results, how do I know if an oval chainring would benefit me or my bike? Well, because we can’t really replicate chainring testing as Absolute Black can, we decided to do some real-life back to back testing with a few of the guys at the shop.
We had a few riders at the shop, including myself on both my cross country bike and my gravel bike, perform a back to back test between oval and traditional chainrings to see if they could notice a difference and see if one feels better than the other. Adam and Chance went through the adaptive period that Absolute Black recommends, with about 10-15 rides over about 2-3 weeks to get used to the differences. Michael had never ridden the oval chainring until the day of the test, so he was fresh to the feel. We then put each rider back on to the round chainring after a test run to see if they could in fact, notice a difference on the same section of trail back to back.
Because bicycles are powered by humans, the way we input power to the bike is not perfect...well not even close. Since power isn’t distributed evenly in a pedal stroke, there are areas that more power is put into the cranks and other spots where less power can be physically put into the cranks. Turns out that this power pattern looks like an oval, who would have thought? Absolute Black’s goal was to maximize that power input when putting the most power out and minimize when the cranks are at the spot with the least amount of power. Each style of chainring has been optimized for the intended use, so mountain bike, road and gravel, and time trial bikes all have different amounts of ovality and are also timed differently to help match the position of the rider on those specific bikes. By making the chainrings oval, you as the rider should be able to put down power more evenly. Now combine this with technical climbing and you can actually be more effective with your pedal strokes making climbing a bit easier. Same with riding on flat ground, having a smooth pedal stroke and power output to the back wheel will make things feel a bit easier. I think this is especially noticeable when riding with flat pedals on a mountain bike, you now can only put down power from about the 2 o’clock position down to the 5-6 o’clock position without being able to pull up. Because of the oval timing, that helps get a smoother, more effective pedal stroke.
Since Absolute Black did all the tests over many months with hundreds of riders, below is some of their comparison between oval and round chainrings direct from Absolute Black themselves:
“It is well known in practice that various adaptation phase is required to get fully adapted to a new pedalling technique. That is why researchers at University of Primorska aimed to explore the effects of long-term adaptation using absoluteBLACK oval chainrings on mechanical and metabolic functions during cycling at submaximal intensity. Seven cyclists who used non-circular chainrings (52/36 or 50/34) for at least one year were recruited. Participants were recreational road riders with no history of muscular-skeletal injuries in the past 5 years and were riding between 3000 and 10000 km a year. Participants used their own bicycles mounted on a direct-drive ergo-trainer and then completed two 5-minute tests at 75 % of their maximal power. In one of the trials, they used round chainrings, whereas in the other, they used absoluteBLACK oval chainrings in the same size. Trials were completed in a random order and with enough recovery between the trials to avoid fatigue effects.
Researchers used special force pedals mounted on the participant’s bicycle and recorded forces at a sampling rate of 1000 Hz. At the same time measuring continuously oxygen consumption (VO2) and carbon dioxide output (CO2) using a metabolic chart. This setup allowed researchers to assess pedalling effectiveness using the index of effectiveness (IE) for the entire pedal cycle and additionally for the downstroke. Average gross efficiency (GE) was calculated as the ratio of work rate (power output) over metabolic cost rate calculated from VO2 and respiratory exchange ratio. Results were statistically compared using a paired t-test with the level of significance set to p < 0.05.” - Absolute Black Science Lab
Summary of the results when using absoluteBLACK oval chainrings tested by Absolute Black:
So as you can see from the tests that Absolute Black has run, there are some very serious improvements that can be made for most riders by using an oval, how those translate into the real world is hard to prove. We have done our testing and formulated our own opinions about oval vs round chainrings, while not a scientific test, we feel that this test is the most realistic for the average rider.
Thus far, I have had the most amount of time on oval chainrings, specifically the Absolute Black chainrings. The two bikes that I put in the most hours on are my Mondraker XC bike with an Absolute Black 32t chainring mounted to my Raceface Next SL crankset, along with an Absolute Black 42t chainring mounted on my gravel bike with Easton EC90sl cranks. At first, I tried it on the gravel bike and immediately loved how it felt, even before the adaptive period. I found that on flat roads I could consistently stay on top of my cadence and the gear which allowed my pedal strokes to feel very smooth and consistent. On climbs with a steady gradient, I found I could ride a gear higher while maintaining the same cadence allowing myself to go faster and have more effective pedal strokes. All of these translate to having a faster average speed and less fatigue over a 2-4 hour ride.
Next, I put it on my xc bike and I won’t lie, I was a bit skeptical to use an oval chainring on a full-suspension bike. For some reason, I had in my head that it might not work as well and cause some “bobbing” or unwanted suspension movement. Well, that also was quickly proven wrong within the first ride or two on the xc bike. There was a bit more of an adaptive period on the xc bike, but once used to it, I found that the same benefits I felt from the gravel bike were also apparent on the xc bike. I was able to stay on top of my gear while climbing and also felt a huge improvement while climbing technical sections. I felt that I had less of a dead zone during slow tech climbing and that I could turn the cranks over more smoothly as well as keep rear-wheel traction better in these situations. The only not so great feeling I noticed on both bikes was when I was tired and fell behind the ideal cadence for the gear I was in. It actually felt harder than compared to a round chainring at that point. I was 3 hours into a pretty big xc ride and came into a double-digit % 1 mile long climb so that might have had something to do with it as well. Turning over the pedals felt just a bit harder than normal in this situation, just something to keep in mind. For myself that is more of a rare occasion as I can typically stay on top of my cadence even into 3-4 hour rides but there are times I realize I am not a pro rider as well.
Overall, my opinion has completely changed after spending 3 or so months on the Absolute Black Oval Chainrings, from being skeptical to really liking how they feel on multiple bikes. The perceived benefits from the oval chainrings are mostly all positive and I feel that I can have a more effective pedal stroke riding on flat ground, steady climbs or maintain traction on steep tech climbs.
“Seeing as this was going to be my first time riding an oval chainring, I went into the test with an open mind and zero preconceived notions. I had heard people claim that switching to an oval chainring drastically improved their pedal stroke and that it was especially useful for flat pedal riders such as myself. I mounted the ring to my Yeti SB150 and immediately went for a ride. At first, it felt a bit weird and I could definitely notice that I was pedaling an oval ring. After about 30 minutes of riding, I completely forgot about it and really started to notice how smooth and planted the bike felt. Obviously I couldn't run any scientific tests, but to me, it just felt like I was getting more of the power down and none of my power was going to waste. When I compared it to the round ring on the same section of trail, the difference was obvious. I noticed that with the round ring I would get hung up on technical climbs and sharp rocks whereas the oval, I could just power right through those sections. With about a month of riding on the Absolute Black ring, I have really grown to love it and plan to keep using it for the foreseeable future.”
"At first, I was unsure if the oval ring even did anything, but after going back to a standard round ring I noticed in very technical climbs that needed some extra power it felt that the pedaling response was increased majorly! In situations where I needed to put down power to get over techy rocks, it excelled incredibly. I was eager to get back on the Absolute Black Oval chainring after comparing the two on the same ride! "
“This was my first time riding on an oval chainring and to be honest, I don't have enough saddle time yet to really tell a difference between the oval and round chainring. My test of the Absolute Black oval chainring involved climbing a rocky portion of the trail which I have never climbed before. There were some sections on the trail where I felt like the oval chainring helped me power over some sections where the round chainring felt dead. I don't know if that's because I got more comfortable on the bike climbing this section or if the chainring really was making a difference. I think with a little more saddle time and climbing some sections that I am really familiar with, I can give a definitive answer on whether I can tell if an oval chainring is really helping.”
After digging into the science and tests that Absolute Black provides along with doing our own testing here with Worldwide Cyclery employees, there are no doubt some real and noticeable advantages to running oval chainrings. From having a more effective pedal stroke, to maintaining traction more on steep and tech climbs. Myself and all of our shop riders who did the test could feel the improvements from the Oval and while Michael isn’t a full believer, he still did notice some improvements while climbing. The Oval chainrings help improve the imperfect human pedal stroke, not only making your pedaling and power more effective, but also make your entire riding more effective. It’s an easy part to change on your bike that can have some significant upgrades to your riding, compatible with tons of cranks, what do you have to lose by trying out an Absolute Black oval chainring?
This article was written / authored by Liam Woods. Liam has been in the bicycle industry for over 10 years as a racer, professional mechanic, service manager and as of late, media and content creator. Liam has ridden thousands of different bikes, ridden countless components, tested endless MTB apparel of all kinds and written reviews on it all. He's a key piece to the Worldwide Cyclery "All Things MTB" content creation puzzle. He also makes consistent appearances on the Worldwide Cyclery YouTube channel and Instagram.