Round: Is It Really That Difficult? Yes, the Simplest Things Are the Hardest To Do Well.
You would expect chain rings to be round, that is, unless they are of another shape on purpose, such as the Rotor Q Rings. When I say round, I mean perfectly round, not almost round. It may not matter all that much for a geared bike because of the rear derailleur with an integrated chain tensioner. Anyone who rides a fixed gear bike knows that it does matter.
For a fixed gear bike, a chain ring that is not quite round is annoying at best and dangerous at worst. The unfortunate market reality with respect to chain rings seems to be that you get what you pay for. Cheaper chain rings are not quite round; perfectly round chain rings are very dear. I understand and appreciate the manufacturing realities. As far as users are concerned, cheaper chain rings represent false economy.
I recently replaced a slightly out of round chain ring of a relatively inexpensive private label track chainset with a Campagnolo Pista chain ring (NOS). Perfectly round and smooth as silk. As it should be. I’m almost surprised.