louis711

Hi,
Im considering getting FC 7100 12spd crankset since it is much cheaper and also better design. Will it work with my 105 R7000 groupset 11 spd: FD, RD, chain and Cogs,....
Thanks !!!

Zaskar

You should be fine.
- The outside width of the chain gets narrower as the cog count goes up, i.e., an 11-speed chain is wider than a 12-speed chain - but only the outside dimensions.
- The inside width - the gap the cog/chainring teeth fill - of the chain is the same - from 9-speed up. So, the inside dimensions of an 11-speed and 12-speed chain are the same.

But (there's always a but)... the ramping of the chains won't be identical - each optimized for the cassettes and chain rings. That means when shifting from the small to big ring, you may (may) feel it. I really don't know what "it" is though. These are fractions of millimeters... at very slight angles. So, it's likely you'd feel no difference in the two chains/chainrings.

And since this is the internet, give it a couple min. and someone will pop in with actual, real-world experience and either blow up or confirm my "should" and "may" hypotheticals.

eduskator

Only thing I can see is the 12sp chainring tooth may be narrower than the 11sp, so the part of the chain that's on the chainring may have a little play (left / right or inward / outward).

GhostRider62

Wrong. No diff

louis711

Thank for answering !
There is little information on the internet, i believe it works however require adjusting FD screw which is a nightmare for me
These are 2 videos i found on youtube, sorry i cannot post the link at the moment
Shimano Ultegra R8100 12 Speed Crankset to 11 Speed Mechanical Drivetrain Compatibility Test
Shimano Ultegra R8100 12 Speed Chainset Is It Compatible With 11 Speed R8000?

Zaskar

The 12-speed chainrings are spaced bit wider than 11-speed

If you're not changing size/tooth count, the derailleur location - vertical on the mount and rotational - doesn't change.

You may need to adjust the H/L settings. Don't be intimidated. This is the easy part of installing, setting up, adjusting a front derailleur. The "H" (High) and "L" (Low) screws simply limit how far the derailleur moves. Your adjustments would be tightening that range... a very little bit. It really is as simple as turning a Philips head screw a tiny amount and watching derailleur move IN about .5mm

eduskator

No difference at all between a 12sp chainring and a 11sp chainring? Allow me to doubt this

Do your homework before misinforming people.

Zaskar

11 and 12 chainrings are not identical. The teeth are cut to work with the ramps on the 12-speed chain... which is designed (plates) to work with a 12-speed cassette. On the crank, the spacing of the small and big rings is also different - 12-speed systems have a wider chainline.

But... compatibility is subjective. These differences are often fractions of millimeters. Sometimes they manifest is just a tiny bit of extra driveline noise - as the chain "lands" on the chainring differently. Sometimes shifting is affected... if you really pay attention. And sometimes it just doesn't work 'cause you did the reverse-compatible thing the wrong way and things just don't fit ;-)

In the OP's case, it will work.

Sy Reene

I think he only maintained that there's no difference in width. not 'at all'. No idea myself though if this is true.