[zender]

Riddle me this:

2012 BMC Race Machine, Shimano BB86 bottom bracket, Dura Ace 7900 compact crank, front and rear derailleurs.

In the small front ring and either the largest or second largest rear cog, at the bottom of the left pedal stroke, even without significant torque, but still clipped into pedal, there is a barely audible click.

In the large front ring, in the smallest rear cog, at the bottom of the RIGHT pedal stroke, there is an almost identical click.

Standing up and mashing doesn't make it go away, soft pedaling with essentially no pressure on the left crank doesn't make it go away. Removing/reinstalling/re-lubing crank, BB, pedals, chain does not make it go away. I cannot see any chain rub on derailleur plates. So it seems, although it is crank revolution dependent, it is NOT torque dependent.

Ideas?

 

[rcharrette]

Huh, sounds like you've covered everything that would relate directly to the rotational noise. The only other thing (and it would not translate directly to rotational noise necessarily) could be the stop screws. Since it's doing it in the largest cog and the smallest cog it may not be sitting on the cog all the way, the limit screws could be to tight.

 

[Roland44]

Huh, sounds like you've covered everything that would relate directly to the rotational noise. The only other thing (and it would not translate directly to rotational noise necessarily) could be the stop screws. Since it's doing it in the largest cog and the smallest cog it may not be sitting on the cog all the way, the limit screws could be to tight.

That's pretty likely actually. It happened to me before and to some of my buddies as well...

 

[okiefo]

Check your quick releases. Be sure they are both tight. I know it might sound ridiculous to suggest that, but I've solved countless creaks in my time simply by adjusting a rear skewer.

 

[SMK-SLC]

Had similar issue on CAAD9 with BB30 (I think). After I could not find the issue took it into the shop who said it was the headset creaking as you put slight pressure on the bars. After cleaning/regreasing the headset no more creak. YMMV.