Originally Posted by
Salamandrine
Yeah I was going to mention that maybe the current issue chainrings will handle narrower chains. Also it should be noted that TA is still going and you can buy brand new Cyclotouriste crankarms etc. They might even have a BB. There's a website somewhere. Not sure if it is French only.
I would think that even the older chainrings would have no problem with newer, narrower chains. All chains from 5sp to 11sp are the same width on the inside (3/32", 2.38mm) and only the outside distance changes. I use a 9sp chain on all my vintage bikes and they have worked fine over a variety of different parts. The only possible place that I could see a problem would be if the chain was narrower than the chainring spacing and would get caught in between, but that hasn't happened with the older cranks that I use....Campy, Zeus and TA.
A few years ago I did some measurements out of curiosity. I measured the chainrings at the base of the tooth since they taper towards the peak and for the back I measured the thickness of the cog itself in a spot where there were no ramps.
Chainrings:
6sp - 2.07mm
8sp - 2.19mm
9/10sp (marked as such) - 2.14mm
11sp - 1.85mm
Freewheel/Cassette
6 and 7sp - 2.05mm
8sp - 1.97mm
10sp - 1.65mm
11sp - 1.65mm