Any advice gratefully received. I'm looking at putting a chainset that has been 'optimized for 10 & 11 speed' onto a 9 speed bike (apparently 9 speed bikes are quaintly old fashioned these days!). Any advice on whether this is wise or not. Losing count of advice scattered over the www that says both yes and no. Manufacturer advises that it should be ok but may cause a lack of performance (whatever that means) - if it means I'll lose 0.7 watts I'm not concerned, if the chain will fall off maybe more so. Cheers.
I'm a big fan of trying these things Andy, it's amazing how often the manufacturer's warnings prove to be overly pessimistic.
Your main problem will be the size of the chain, in particular its width. Nine-speed cassette cogs are, I'm told, a little thicker than ten and eleven-speed. So the chain will grab the cassette without wobbling around but may not be such a snug fit on the chainrings?
But, who knows, you may have no trouble at all, we are talking fractions of a millimetre here. Best of luck.
Technically it should work. Your drivetrain might not be as silky smooth or whisper quiet as it could be using perfectly matched components (that's the lack of performance they're on about I'd say). The difference is minimal with 11-speed chains being a little bit narrower - so the chainrings will probably be slightly narrower too I'm guessing.