Ovum or OVAL
Having experienced the awful original Shimano Deore XT Biopace I had back on my first mountain bike in 1990; a Marin Eldridge Grade nonetheless, I was intrigued by the claimed advantages of a 'modern' oval chainring. It is claimed that because we do not produce even power through a pedal stroke an oval chainring works by making the spin cycle a lot smoother through the stoke with the downward stroke being harder; where the most power is produced, and easier through the dead band where the cranks are horizontal.
This means that a 28 tooth oval chainring is equivalent to a 30 tooth ring on the downward stroke when your legs are at their strongest, and a 26 tooth ring when they’re at their weakest.
Makes sense? Probably not! Absolute Black claim that "Oval rings make the spin cycle a lot smoother and are easier on legs while climbing" Sold to the Monkey!
Wanting to instantly turn my legs into someone with superhuman powers and excited by a simple install I opted to change out my 30 tooth Race Face chainring on my Next Cinch crankset for an Absolute Black 28T Oval chainring with an ovality of 26/30T. The chainrings are CNC machined 7075 Aluminum and available in a 26 to 36 tooth range to fit a myriad of different cranksets. Having only four colour options; which didn't include turquoise, I opted for black.
Installation is easy and just involves making sure that the mark on the chainring aligns with the right crank arm so the 'timing' is correct. Get this wrong and you will make your world very hard! Chain length isn't changed and if you are compeitent at chainging a chainring this will be a breeze.
Once installed a quick counterclockwise rotation of the crank show's you just how oval this thing is. It's really oval - disturbingly so in fact. When I first set off on the trail I am really not convinced at all. My brain keeps telling my legs 'this ain't gonna work', my legs keep telling my brain 'I can feel every rotation' and I feel like I am riding a clown bike with egg-shaped wheels. But as soon as I hit the first section of solid singletrack it all changes for the better.
Just like magic, I am seemingly going faster with less effort. The exits from the corners seem to pop with acceleration and before you know it I am flying along smiling like an idiot. It's quite amazing but somehow I just have more drive and it really is quite magical!
The corner exit acceleration is put down to the increased consistent torque and when faced with a technical rock section I just seemed to be able to climb over it with ease. I opted to move from a 30T chainring down to a 28T oval chainring with an equivalent 26/30T 'range'; however, in retrospect, I would probably suggest sticking with your original chainring size and getting the benefit of the extra 'power' - in my instance a 30T oval chainring with an equivalent 28/32T 'range'.
Coupled with my new oval chainring purchase I also included the Absolute Black Oval Guide chain guide in my order as I was paying for shipping anyway. Absolute Black claim this 'is the only chain guide on the market that is designed specifically for Oval chainrings'. After fitting the oval chainring I refitted my MRP 1x High Direct Mount chain guide and after much fiddling couldn't get it to fit without clashing so I fitted the Absolute Black Oval Guide.
On the bike it's clean and functional and at a claimed 29.2g with titanium hardware it really does 'Weigh virtually nothing'.
On the trail, it works as advertised and I am yet to drop a chain. There is a little visible rubbing wear but it doesn't seem to have hindered the chain line in any way. Its form is a little agricultural and by no way as sleek as the carbon MRP 1x but it does the job well.
8 / 10