Originally Posted by
Andy Somnifac
And I guess I need to update this. It seems that it isn't coming from the rear. It just seeed that way while pedaling. It is only happening in the small-small combo (I know, cross chain bad, and it's a combo I won't be using). What seems to be happening is that the chain is ubbing on the inside of the big ring and catching on the pins and making a big pop each time it gets caught.
So, my question is: are there spacers that can bring the drive side crank assembly out a tiny bit? It won't take much, as the chain line is such that it doesn't rub once I shift up one cog from the smallest.
You don't need spacers, you need to stay out of that gear combination. There is no reason to ever use it as it is hard on the chain and serves no useful purpose. An equivalent gear ratio is available elsewhere.
Having the chain rub on the inside of the large chainring when cross chained or even in the second smallest cog is common with compact cranks (50/34) and not unheard of with standard (53/39) road cranks so what you are experiencing is both common and avoidable.