Strange Drivetrain Noise--road bike

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about two weeks ago i noticed and intermittent noise from somewhere in
the drivetrain...almost like a binding or craking type noise...i hear
it but i don't feel anything through the pedals..all bolts (crankarm,
chain ring, etc.)are tight...it then went away...i heard it again
today...it seems to me to be chain related...i recently replaced the
crankset including hte chain rings...when the cranks are rotated
backwards the chain runs smoothly without evidence of a tight link


any thoughts on what to try?