Mechanically, the Stages Power L and all gen 1 and gen 1 left-side power meters are100% compatible for use with Osymetric, Q-Ring, Absoluteblack, and other non-round chain rings. 

Our power measurement through a Stages Power meter is event based, where as an event is one complete pedal revolution. Due to the changes in velocity non-round chain rings produce through the course of an 'event' you will see that your power will be skewed higher than with a round ring, which has a constant velocity throughout each event. Through our own testing, and using a hub-based meter as a control, we conclude that there will be a 4-5% increase on the readings from a Stages Power meter when used with a non-round chain rings. We recommend that our customers take this into account when changing from round to non-round chain rings, as they may need to adjust their functional threshold power accordingly. 

Note: Stages Power R (and right-side power meters within a LR set) may have limited compatibility with after market chainrings due to the required clearance for the power meter pod. We recommend test fitting any after market chainrings before purchasing to guarantee compatibility.