Kabuto

FC-9200 cranks are for 12 speed Dura Ace, whereas FC-09 cranks are Shimano's replacement cranks for FC-9000 and FC-9100 11 speed Dura Ace cranks. Obviously, the attached chain rings are different (12 speed chain rings on FC-9200 and 11 speed chain rings on FC-09 - edit: the small chain rings are actually identical), but the FC-9200 and FC-09 crank arms look identical. Are they though? Does anyone know if they have the same chainline, Q-factor, and ring spacing?

I know that FC-9100 is designed around a 135mm O.L.D. and has a 43.5mm chainline and 146mm Q-factor, whereas FC-9200 is designed around a 142mm O.L.D. and has a 44.5mm chainline and 148mm Q-factor, but I haven't been able to find any information about FC-09. I think there's a difference in ring spacing too, but not sure how much.

Basically, I'm wondering If I get an FC09 crankset now and run it with an 11 speed drive chain for a while, and decide later on to go 12 speed and install 12 speed chain rings on the FC-09 crank arms, will it be effectively identical to an FC-9200 crankset with the same chainline, Q-factor, and spacing between the big and small rings?

FBinNY 

I'm not versed in the details of Shimano components, but it's possible that the difference is in the tabs that the rings mount to.

A change in the thickness would mean a change in the gap between the chainrings, matching the chain width and FD travel.

I offer this not as fact, just worth considering.

Kabuto

That's certainly a possibility!

Anyone know with certainty what the difference is, if any?

delbiker1 

My experience, while not these specific rings, is the fit of the rings on the crank arm is slightly different, but can be altered to fit with a bit of filing. That is actually with a couple of different Shimano cranks, both 11 speed. I did not have a problem with the thickness of the rings. The shape of the tab where it meets the mount is slightly different.
I do not know that the same is true with the DA.

Iride01 

If you look at the exploded diagram for the FC-09 it shows that most of it's parts are compatible with the FC-R9200. However a finish and shape or other visual differences will be seen.

https://si.shimano.com/en/pdfs/ev/FC...FC-09-4988.pdf

Not sure why they don't show the spider/right crank arm part number. Is it not part of the package? Can't seem to find the other details of chain line or such that you ask about.

FYI, I run a Shimano 105-5800 spider/crank with Ultegra 8000 series rings and a Ultegra 8000 series left crank. The profiling on the spider is different than the profiling on the ring. So the mating points look funny when you are close enough to realize they are different. One is not as glossy a finish.

wschruba

All of the 11-speed "replacement" cranks are, per Shimano, 12-speed cranks with a specially made 11-speed ring, to properly bring them in line with the expected metrics for an 11-speed drivetrain.

The small chainrings on all of them are stamped "12-speed".

Kabuto

Thanks for the comment! "per Shimano" means Shimano has announced this somewhere? Is this information online?

If the difference is just the specially made 11-speed ring to properly bring them in line with the expected metrics for an 11-speed drivetrain, that would mean the crank arms themselves are identical.

In that case, why would Shimano stamp the replacement cranks with "FC-09" and and 12 speed cranks "FC-R9200"... hmmm

wschruba

Tracking purposes, I would think. They don't share why they do things, just that they do.

If it's labelled with a discrete part number, it would be easier to track than a collection of disparate parts, methinks.