The Absolute Black premium SRAM compatible oval chainrings (110/5bcd) are designed specifically for SRAM cranks that have 1 hidden chainring bolt behind the crank arm: SRAM Red, Red etap, Red22, Force1, Force22, Rival, Rival1 and more.
Both, inner and outer oval chainrings are optimised with smooth shifting in mind. This is why the back of the Absolute Black oval road chainring do not feature cutouts, like other oval products on the market. Instead, they are designed with smooth, angled surfaces to facilitate chain movement quickly and precisely between the chainrings giving a positive and definite shift that is often lacking in other oval rings. Absolute Black outer oval chainrings have 6 up-shifting ramps, for easy and quick gear changes, even under load. Each outer chainring also features 12 down-shifting points. Instead of steel shifting pins, Absolute Black use a CNC machined "ramp and recess" solution where special raised ramps work in conjunction with the tooth recesses to stabilize the chain when shifting. The oval chainrings do not require any modification to the (standard) front drailleur in order to work properly. Simply align the derailleur with a 1mm drop to the top of the chainring at its highest point and allow for a 2mm gap between inner mech plate and the inside of the large chainring, in the highest gear combination (small sprocket / large chainring).
The Oval chainring is far from a new phenomenon but there are some that perform better than others.
The Absolute Black premium Oval road chainrings have been independently proven to help riders deliver their power both more effectively and with less exertion. In a study conducted by the university of Primorska, Slovenia; Absolute Black Oval chainrings were demonstrated to deliver up to a 9% increase in force effictiveness (power delivery through the pedal stroke), a 7% reduction in Oxygen consumption with up to 15% lower respiration rate, while at the same time delivering a reduction of up to 10% in heart rate. In other words, Absolute Black oval chainrings allow riders to deliver the same power for longer periods and with reduced effort. If you are a climber - or perhaps if you are not - you will feel the benefits more as you climb higher, as Oxygen levels dip and exertion typically increases.
Much has been made of the potential damage that Oval rings can result in for riders' knees - but much of this was based on the Shimano Biopace chainrings of old. Biopace ring profile is demonstrably wrong, with timing of the oval shape incorrect and which could result in knee issues. Since Biopace is long gone from the market, the current technolgy can be viewed as an entirely new product and Absolute Black rings feature ovalisation pitch and timing that is optimised to enhance the pedal stroke and complement human physiology. Oval chainrings maximise the part of the stroke where power is produced and minimize resistance where it isn't. As a direct consequence, Oval rings enhance a cyclist’s ability to spin with a smoother power delivery and feel easier on legs while climbing.
Many will view the use of oval chainrings as something reserved for the pros or those competing at high levels in road racing and triathlon. Conversely though, it is us mere mortals that benefit the most from the technology. Switching to oval rings is an extremely effective way to correct an imperfect pedalling action – helping us to smoother power delivery that the pros developed through thousands of hours of training. One of the key reasons the benefits of oval chainrings have historically been hard to prove in lab tests, is because they were nearly always done using Professional riders – as a user group they are the least likely to gain a performance increase from a switch to oval. Where oval rings shine however is with rest of us, who ride for pleasure and not for a job.
Even if our pedal stroke hasn't historically been all that bad in and of itself, there are often other factors that result in degredation of our form. I'm a pretty good example - as I generally am when it comes to physiological imperfection! I have a right leg that loves to pedal, and a left that doesn't...
Over the last 20 years I have damaged my left knee in crashes twice, and torn my left achilles tendon on 2 separate occasions. Combined with a once-torn left hamstring and a lower back that persists in fighting this irate left leg for control of my pelvis, I have a less than graceful left leg pedal stroke. It is one that has caused issues with my already beleagured knee. I recently switched to Absolute Black rings, not for improved numbers (though they have definitely helped) but more for relief of my left leg - specifically the knee. Being of a scientific bent, I have repeatedly switched between Oval and Round rings for weeks at a time to see if I can feel the difference and I can say in good conscience, that the reduced load on my knee from the use of the Oval rings has significantly reduced any irritation I have had in my left knee. As an added bonus, the interval between visits to my osteopath have also increased. I say this as one who has always been sceptical of the oval ring and one who recently returned from riding Nice to Geneva with zero issues other than wet shoes and an angry saddle sore!
So why Absolute Black specifically? Unlike other oval chainring brands who have a singular oval profile, Absolute Black have a unique ovalisation (called 'clocking' as it relates to the degree and timing of the ovalisation of the ring) for each of their chainring sizes or size ranges. This ensures the perfect clocking regardless of ring size and it is what sets the company apart.
Ultimately, you may not feel that you need them but as far as I am concerned, I'm a convert. A small investment offers genuine energy savings, more efficiency and - certainly for me - improved loading that reults in more enjoyable cycling, which is the ultimate goal. From comfort comes speed!