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Ultegra R8000 crankset compatible with Di2 10 speed?

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Ultegra R8000 crankset compatible with Di2 10 speed?

Old 05-14-20, 07:31 PM
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CerveloS5
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Ultegra R8000 crankset compatible with Di2 10 speed?

I have a mix of parts on my S5 and recently decided to install an Ultegra R8000 crankset 50/34 in favor of the Rotor 53/39 that was on it. The bike has Ultegra 6770 Di2 10 speed (11-28 cassette), which I'm fine with. I used the wheels mfg adapters to go from the Rotor's 30mm spindle to Shimano 24mm. Install was without issue. I've adjusted the front and rear mech, but I can't get the FD to go to the big ring. The shifting at the RD is not as buttery smooth as it was with the original Rotor setup despite the Di2 trim adjustments.

Am I doing something wrong or are these parts just not compatible? I'm new to the Di2 and adjusting derailleurs in general.

Last edited by CerveloS5; 05-14-20 at 08:54 PM.
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Old 05-15-20, 12:11 PM
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Another thought that ocurred to me was the wheels mfg adapters. Would they push the chain rings further away from the FD than the original Rotor? At full extension, it doesn't seem like the FD can get the chain past the big ring.
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Old 05-15-20, 12:24 PM
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I have had no problems with first the 6770, then the 6870 FD shifting on an Ultegra 6800 or 105 5800 series 50/34 chainsets.
Are there any spacers on the drive side of the BB or inside the CW on the axle? Looking down from above the small chain
ring should be ~4-6mm inboard of the drive side BB cup. Is the FD at the right height on the seat tube relative to the
big ring? Without a chain how far out does the FD cage move ie no chain installed, does the FD move out over the big ring
when upshift commanded? Looks like you already posted some of this with your second post.

As an aside, your 6770 brifters will work fine with the 6870 or 8050 series 11 spd Di2 FD/RD. If you ever get the urge to
upgrade all you need are the RD/FD and a cassette. You won't need new brifters.
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Old 05-15-20, 01:39 PM
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Originally Posted by sch
I have had no problems with first the 6770, then the 6870 FD shifting on an Ultegra 6800 or 105 5800 series 50/34 chainsets.
Are there any spacers on the drive side of the BB or inside the CW on the axle? Looking down from above the small chain
ring should be ~4-6mm inboard of the drive side BB cup. Is the FD at the right height on the seat tube relative to the
big ring? Without a chain how far out does the FD cage move ie no chain installed, does the FD move out over the big ring
when upshift commanded? Looks like you already posted some of this with your second post.

As an aside, your 6770 brifters will work fine with the 6870 or 8050 series 11 spd Di2 FD/RD. If you ever get the urge to
upgrade all you need are the RD/FD and a cassette. You won't need new brifters.
Thank you for your helpful post! There are no spacers on the drive side, only one 1mm spacer on the non-drive side. I don't know what you mean by "inside the CW on the axle"? I just took a look down from above and it does look like the small chain ring is ~5mm inboard of the outside end of the BB shim. The BB shim is about 10mm thick so it looks like the small ring lines up with the side of the shim closest to the frame and sits about 5mm inboard of the outer edge of the shim if that makes sense? Below is a pic of the instructions to install the BB shim into a BBright bottom bracket. You can see the thickness of the shim is about 10mm.



I adjusted the FD height to about 2mm above the big chain ring. I will remove the chain to see if the FD will move out over the big ring. If it doesn't move out over the big ring, what can I do to fix that?
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Old 05-16-20, 11:47 AM
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wheelsmfg.com is thought by my antivirus to have "malicious software" and refuses to allow any downloads.....
It does appear that your CW are too far out and you will have to figure out how to reduce the thickness of the
BB shim, if I am understanding the pix you posted. From the L pix there is a tapered black object that is
struck by the mallet to install the adapter, is this removed after the install is complete?
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Old 05-16-20, 05:49 PM
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I took off the chain and tuned the Di2 front and rear derailleurs again from scratch. Not sure what happened the first go around, but I was able to get the FD adjusted properly. Reinstalled the chain and it shifts perfectly front and rear! Thanks for your help sch - guess I can now confirm that Shimano R8000 crankset is indeed compatible with older Shimano 10 speed cassette.

BTW, thanks for the info on the 6870 and 8150 11sp. I wasn't sure if my Di2 was too old to run 11 speed. I have an alloy and carbon set of Mavic wheels that are both set up with 11sp hubs so I may get there eventually
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Old 05-17-20, 01:38 PM
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Yes, the occasional availability (formerly, haven't checked since the 8050s came out) of 11 spd Di2 FD/RD for under $300 and then a $60
cassette, the significant increase in gear range has its attractions. The 11-32 cassette is really nice but will be replaced with
an 11/34 when it finally wears out. An additional FWIW, in my experience Shimano/KMC/SRAM 10spd chains all work fine on
11 spd cassettes at least on the 3 bikes I have done this and the HG800 / HG700 11-34 11 spd cassettes fit on 10spd hubs.
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