Chainring for a Shimano FC-CX50
A CX-50 is usually fitted with 46-36 and is 10 speed. Occasionally I replace the 36 with a 34 on mine. Any flat 110mm BCD ring of 50/52 will fit instead of the 46 ring and the 36 is the usual combination with a 52.

The chain will have to be 2-3 links longer and the FD must move up by one or two mm to clear the big ring.

(Note: You may even change the rings without having to remove the crank from the bottom bracket, as they can easily be manoeuvred around the arms and the pedal.)