mkemmer1

Is that compatible (compact crank)? Thanks to anyone who can answer!

Iride01 

With what other pieces parts of the SRAM group? The smallest DuraAce crank is 50/34 I think. So if you are using a SRAM rear DR with whatever size cassette you are planing on, then you have to run the capacities and other specs.

Usually those specs can be exceeded by a certain amount. But you aren't giving any useful details about what you are wanting to do.

I can say with confidence that a 12 speed chain will work on a 11 speed crankset. Whether or not that combination will work with any of your other components, I'd have no clue.

mkemmer1

Thanks for the answer - it would be a dura-ace compact crank 50/34, using Sram etap drive train ->Chain, 12-28 cassette, shifters, derailers. cassette can be variable though.

I've gathered that the Sram etap 11 speed would work with Shimano cranks, I just wasn't sure about the 12 speed

hrdknox1

I would think not. The chainline is narrower on the 12 speed. SRAM states their 12 speed crankset has a 45 mm chainline, and their 11 speed crankset has a 45.5 mm chainline. The .5 mm difference might be enough to affect precise shifting . The chainline centers the outside chainring with the cassette.

fietsbob

Chain line ... on the back, is the space between cog 6 and 7 of 12 .. it's a measurement to the baseline center line of the bicycle ..

set up the space between your 2 chainrings to also be on that chainline...

mkemmer1

Thanks for the replies. A half a millimeter difference seems so small, I'm hoping I can adjust the chain rings if I have to. But I'd really like to get a good answer before I invest any money an etap Drive train minus the cranks. My concern was the flat top 12 speed chain working well with the Shimano cranks.

Iride01 

.5 mm isn't that much to me either. It would only be too much if using the SRAM crank already had you at the limit of tolerance for that side of it's shifting range with your bike frame.

Crank won't care about flat topped chain. What you might try to find out is if the spacing of the chainwheels on 2x 12 speeds are much different than a 2x 11 speed.

Assuming that the crank is what you already have on the bike, if it does seem to not shift as well after putting on the eTap, then you might lean more toward getting an SRAM 12 speed if there was a big difference in chainwheel spacing. But if there is only a few tenths of a mm difference, and you are having shifting issues, then look more at the other pieces parts before giving up on the oddball crank completely.

ljsense

In general, there's usually enough forgiveness to run a crankset that is one generation off and still have the drivetrain work well enough.

For example, using a 9-speed crank with a 10-speed chain works ok; I've done that plenty and didn't notice much performance lost.

I've also run a Campy 10-speed crank with a 10-speed Shimano chain, and other combos that were one click away from what the manufacturer specified.

My guess is that you'd be in that ballpark -- functional, but sometimes wondering what that noise or slow shift was about.

Would like to hear a report back if you try it. Running Shimano cranks with a SRAM system that was the same speed was often a way to get better shifts. But with the 11/12 system, I wonder how it will work.

squirtdad

fwiw......think long term not short term bucks. IME using matched components eliminates a lof of fiddly issues both initial set up and long term riding .5mm is not much and maybe the electronc trim will work. In any event there is some degree (even small) of issues if not as manufacturer specced ymmv