On the last few rides I noticed a click, a metallic click that only happened when I was out of the saddle. So, out on the road, I made sure that the cable ends where not clicking or catching on my shoes, they weren’t.
The noise sounded like it was from the rear of the bike. Don’t let this fool you though, bike noises can travel through the frame and be somewhere else completely.
I knew however, the likely cause was the chainring bolts, as I’d recently replaced the chainrings.
So, tightening this bolt up to the recommended torque of 7nm, and noise stopped.
However if you don’t know what is causing the noise, just work methodically, push and pull things like your cranks, ensure bolts are done up to torque, and greased, check for play in bearings. Spin cranks backwards while looking for jumps in the rear derailleur, You’ll find it eventually.