I know some cranksets I've had in the past have had a little side to side movement, especially when I mash on the pedals or am standing while climbin.
On the late 60's Gitane I just finished I was doing some fine tuning and noticing that the crankset seems to have some wobble in it as it rotates around - no pedalling, just spinning it around. Probably a 1-2 mm - can't get a real accurate measurement. I can usually see it fairly well sighting straight down and using the front derailleur cage as my gauge. Wondering if I might have a slightly bent large chainring.
Any advice on how to accurately check the ring. I tried a level but that didn't seem to work too well. it's a 5 pin crank and the two rings don't separate - just the arm.
Here's a photo of the crankset - I like it because of the 52-36 gearing.