The Case For Oval Chainrings
Hey friends, Bender here. Tech time. They’ve been discussed (more often argued) up and down online more times than imaginable, but I want to share my experience with oval chainrings. Between my Instagram being overrun with advertisements and one of my riding buddies switching his entire stable over to oval rings and raving about them, my engineering brain had to see what the hype was about. It’s been widely agreed that Shimano’s attempt at the concept with their “BioPace” back in the 90’s was a flop, having had the mechanics exactly wrong by today’s research. I’ll spare you the nuts and bolts of it all, as there’s hours of reading to be found on the interwebz if you’re inclined, but fast forward a few decades and the concept is back, this time promising to be effective.
I put an Absolute Black brand oval on the fatbike last fall. From my research, it’s one of the more-exaggerated ovals on the market. My mountain bike hardly leaves its garage hanging hook after Iceman, so I ride fat almost exclusively from mid-November until at least mid-March. The oval sensation was absolutely noticeable at first; “odd” is a strong word here, but definitely different. It quickly became normal to me. I jumped on Munson’s round-ringed fatbike for a hot second on his #newbikeday ride mid-winter, and immediately noticed the lack of ovality… good or bad, I hadn’t ridden oval enough to determine, but again, noticeable. I felt strong on my fatbike all winter, so I kept spinning the oval.
Spring comes. Mountain bike still doesn’t have round and rideable wheels since I served up tacos at the Dragon last fall. So the fatbike fills the gap an extra month into spring.
I finally build up some wheels. Mountain bike hit’s the ground. I show up with pretty fresh legs to duke it out in some tight, twisty singletrack with a group of thoroughbreds on my weekly Tuesday night ride stoked on my new hoops. And proceed to get dropped like a brand new phone on the cement without a case.
What happened?
Every punchy hill, after every tight curve through and around trees, after every brake check, I’d try to push the watts but not get the spinup I’d grown accustomed to on the oval
I’m a low-cadence guy, a mild masher. The oval speeds up the crank rotation in the weak part of the stroke where you’re putting down the least power, just enough to carry momentum into the power part of the stroke; it’s almost a springboard effect for me. In my experience, this has translated into less shifting in technical sections and more effective transfer of 5-second power. Going back to a round felt like I had no legs or was dragging a brake. So I immediately put an oval on order for the mountain bike.