Stand up, do you still feel it? Probably just eliminated seat rails and post.
Swap the pedals with those plastic junkers the shop threw in with it on day one. Still feel it? Not the pedals.
Remove the chain and pedal while coasting. Stopped feeling it? Something in the drivetrain. Still feel it? Bottom bracket or crank arms.
I spent way too long trying to find a ticking. Mine was audible though. Turned out to be a pedal.