I'm looking for a chainring compatible with bb86 I'm trying to invest in a new powermeter (never had one) but my current cranks are FSA Gossamer which are no longer in stock by most. I looked at power2max and they don't have a compact chainring. Is there a list/chart with chainring compatibilities? If not is it possible to use a bottom bracket adapter to something more common? (like shimano 105 5800?)
I'm not sure about a list of chainring compatibilities. 
I had a similar issue when I wanted to upgrade my drivetrain. My BB30 wasn't compatible with the DA9000 crankset, so I had to buy an adapter. Shimano makes an adapter for the BB86 if you'd like to buy a new crank based power meter, however, it may be worth investing in a pedal or hub based power meter instead as drivetrain changes can be finicky. As a side note, I've never had any problems with my BB30 Adapter and I've been running it for a little under a year. Good luck!