Has not happened to me, but I have heard that a seatpost can click on the inside of the seatpost from frame flex.
I can't remember the sum total number of causes of clicks and creaks that sound like they are coming somewhere at or near the crankset on my various bikes over time, but they range from:
- a click in the pedal bearings (which reminds me, I still need to take that pedal apart),
- a lower rack bolt at the dropout that was not as tight as it should be, the rack shifted
on the bolt with each pedal stroke from frame flex,
- a non-drive side bottom bracket bushing on a UN-55 that was not as tight as it should be,
- perhaps the most obvious culprit, chainring out of true caused a clicking on front derailleur,
- pump in the bracket screwed to the seat tube shifting in position with each stroke, frame
flex caused the pump to click on the seat tube,
- a small plastic box with my cash and credit card in my jacket pocket clicking on my keys,
- saddlebag shifting in position as my leg bumps it on each pedal stroke,
- SPD cleated shoe rubbing on the pedal with each pedal stroke,
- and of course, the dreaded creak of a not-tight-enough square taper crank arm bolt.
Discovered a new one a couple days ago. My one year old road bike, it really sounded like the left side pedal. Pedal is about 15 years old, lots of distance on it, likely the culprit. I put the bike on the bike stand and started to remove the pedal from the crank arm and as I turned the crank to put the pedal wrench on the pedal, I heard the click, moved the crank arm back and forth a few times and the crank arm clicking on the water bottle cage under the downtube was clearly audible. That water bottle cage was held on to the frame with two of those Zefal plastic bands, I use that cage to carry a bottle with my spare tube, tools, patch kit, etc. The cage had shifted to the side a bit where the cage touched it on every stroke.
https://road.cc/content/review/11601-zefal-gizmo-extra-bottle-cage-mount
