I just measured chain ring spacing on the four cranksets installed on the household bikes: Shimano FC-6800 (11-speed Ultegra) with Shimano 4-bolt rings, Sugino XD600 with a variety of ring brands, Sugino AT, and Specialized “flag”. The last three are 8-speed setups all 110-74, the last two both use TA “9/10 speed rings”.
It’s not an easy measurement with installed cranks, but I could not find any consistent difference between them that would disagree with
RiddleOfSteel ’s more accurate 7.5mm number above. If anything, the 11-speed
might have been a touch wider, offset by the sloped inner face on the big ring.
This confirms to me that “N-speed” cranksets (insert any number for N, probably 5 and up) is largely marketing hoohah intended to separate you from your upgrade money. I’m not a fan of outboard bearing BB’s, either. Fixed something that wasn’t broken!
Cog spacing, however,
has changed for Shimano: 5.0mm for 7-speed (and Campy 8-speed), 4.8mm for 8-speed, and I can’t remember after that (ask
Sheldon Brown if you must know). Chain
outside width has also changed to go along with the tighter-cog spacing. My several beloved Sachs Ergo shifters, apparently from both eras, certainly prefer different cog spacing. The Marinoni is lovely with 5.0mm, the Miyata shifts perfectly with 4.8mm, but they don’t like to use the other’s cassette. Good thing I have plenty of cog spacers for my custom 8-speed cassettes made from loose cogs.