I've been running oval Rotor and Garbaruk chainrings on my road and gravel bikes for years, but have not used any on my single-speed or fat bike even though the benefits of oval rings would be particularly advantageous on these two bikes. On my FatBike I've dialed the chain line to an optimum with a round 28T Wolftooth chainring. Due to a lack of chain stay clearance an oval ring would not fit without me increasing the chain line. Until now, my single-speed was equipped with a round 34T titanium chainring for technical reasons also. My favorite MTB crankset - Rotor's Rex 1.2 - had a 5-bolt, 110 BCD spider. The smallest oval ring for that bolt circle diameter is a 36T - too large for a SingleSpeed in mountainous terrain - I don't have quite that power. This all changed now because Rotor expanded their direct-mount chainring options to the Rex line of cranks.
Since chain stay clearance would likely be an issue and my legs are getting older, I purchased a 32T DM Q-Ring and therefore went two teeth smaller than what I used to ride up to now. The chain line of the 32T DM Q-Ring was about 3 mm shorter than my previous setup with the Rex 1.2 spider. Luckily, I was able to shift the whole crankset towards the drive side by 2 mm by using different axle spacers. Lucky too that I actually had just the right spacer. Next, I pulled out a 9-speed SRAM chain which I thought was new. The chain had never been ridden, but it must have come off one of my collection bikes I sold because it had been shortened. As luck would have it, the chain had just the length I needed; no further shortening was required. When I proceeded to put on the chain, I had to discover that my 19T Homebrewed Components cog was worn too much. So, off with the wheel to install another Homebrewed Components 19T cog. Lastly, chain tension had to be adjusted. The rear wheel moved forward a little bit. Overall chain stay length is now a few millimeters shorter than before.
So, about such a ring on a single-speed? One word – ridiculous! Total game changer. My pedal stroke feels rounder and more fluid. When the climb isn’t steep, it feels more relaxing. The legs just pedal smoother. On long rides, an oval chainring gives me more opportunities to recover after a hard effort. Whenever possible, I’ll be running oval rings.