Weight Weenies

I am about to get a new set of compact cranks on a Di2 equipped bike and wondering what NON Shimano options work well before I commit to the Shimano ones
- SRAM Red Exogram?
- Campy SR/R
- FSA

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The Shimano cranks are pretty nice, and there is nothing about them that makes them Di2 specific.
You can pretty much use all of those suggested, but many here would take great umbrage at you mounting Campy or SRAM cranks on a Shimano bike. If you have BB30 or other standards that can use an adaptor, then the Cannondale cranks might be nice if the budget allows, along with some of the other aftermarket cranks (plenty of threads on those).

The line given by Shimano for using their cranks and rings is that the three dimensional construction of their DA rings makes them stiff enough to resist the forces imposed by DI2 front shifting. Apparently there were some broken 7800 rings during the time they were field testing the DI2 systems, before they had developed the 7900 chain ring design.

Other rings may indeed be stiff enough to resist the forces of DI2, though not as stiff as the DA rings. It sounds like you've decided that the non Shimano options are stiff enough for you, though.

Take it as you will.

Any crank with Praxis Chainrings.

I run THM's M3 with Praxis ring and have no shifting issues.

Rotor 3D with Stronglight CT2... shifts like a dream.

I am converting to Red Exogram (keeping the CT2's). To avoid the combination of Shimano and Sram on the same build, I will sand them down, and keep them in nude carbon.

As said prior, there are lots of threads regarding these issues.

Yes you are right there are plenty of posts about the topic but many conflicting views, hard to know what to believe

I'm trying to sort through these to find the truth

- the da 7900 crankset is specifically designed due to the tremendous forces that the FD servo generates. Not many others can cope with the stress
- the spacing between the chainrings is unique to da and using other cranksets with a different gap will result in the auto trimming not working as intended

I am not worried with mixing and matching, i've never really loved the look of the stock da crankset. I also run a bike with campy sr which i really like the performance of and look of and if they worked I would definitely try them but I can not find anyone who has used this combination successfully.

I am interested to see what the alternatives are...

How much stress can that little FD motor really create? It's about the same size motor as you would find in a $10 toy car.

I have a hard time believing that motor puts more stress on the rings than a sprint would. I think that is just some marketing BS Shimano came up with to encourage people to buy Shimano cranks.

OP, personally, I don't like mixing Campy/Sram/Shimano, but I am very OCD - My closet is organized by type of clothing and color. But that doesn't mean you couldn't use FSA, Rotor or any of the lightweight options out there.

I agree that the amount off stress that di-2 puts on the rings isn't that muchs bigger that a manual FD.
I us a compact Rotor with Rotor chainrings combined with di-2 on a Cervelo R5 and everything works fine and with zero problems so far (10k miles)

I use Zipp Vuma Quad compacts with no issues, the rings are still perfectly straight and true after a year of riding.

I do however ease a bit on the pedal stroke when going from small to large. I want to save my drivetrain.

Have used both Zipp Vumaquads and also Ax Lightness Morpheus with Stronglight CT2 rings (and also the carbon DA cranks with the CT2 rings) - all worked well with Di2 - CT2 rings seem to work particularly well.

Spent last year on Rotor 3D+ and Q-rings with Di2 drivetrain. no probs at all.

You would be absolutely floored at how powerful that Di2 stepper motor is! When activated against an unpedalled crank, the rings visibly deflect. If you accidentally caught your finger in there, it would shear your finger off. Small children need to be warned never to play with a Di2 bike, as that could be a real tragedy. My four-year-old would do that, until a dramatic demonstration with a pencil... When working on your Di2 front, unplug it.

Back to the shifting, Di2 will work with any ring, but due to the power of the thing, it is best with Dura-Ace 7900 rings. The spacing of the rings is optimized for Shimano, as it is factory pre-set for sweep. Campagnolo ring spacing is very slightly different and I have never tried a Campagnolo crank on Di2. Most other cranks use Shimano ring spacing, so you should be good there.

I am using 1990s vintage Sweet Wings cranks with CT2 chainrings... shifting is great.

Geoff wrote:The spacing of the rings is optimized for Shimano, as it is factory pre-set for sweep. Campagnolo ring spacing is very slightly different and I have never tried a Campagnolo crank on Di2. Most other cranks use Shimano ring spacing, so you should be good there.

Isn't this what the high and low trim setscrews are for on the FD? I assume you can use it with any spacing you want on any double chainring crank.

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