Di2 XT/XTR with Road Crankset

[Lovetoclimb]

Who is running this setup or knows someone who has?

The skinny is I want to keep my existing gear range: 46/34 crankset with 11-40 cassette but switch from mechanical 8020 to di2 8070. I am guessing I will need XT front and rear der to manage this, but there is limited information on people who have successfully pulled this off. Sounds like the BB shell of the bike and mounting position of the front der. play a key roll in if you get chain rub.

FWIW I would be installing on an Ibis Hakka MX.

Thanks for the help!

[John H.]

You should be able to accomplish what you want with an 8070 group.

I run a 34/50 and 11-40 on my Open. I use the RX rear derailleur (clutch) and a Dura-Ace 9170 front derailleur (I have DI2).
Mine works perfectly.

A 46-34 should be even tighter-

Also- I know guys running Ultegra doubles on Hakka MX's- they work well.

[NHAero]

@John H. - to make sure I understand, you are running the Ultegra RD-RX800 Rear Derailleur with a 16T front differential and an 11-40 cassette, for a total of 45T differential? And the RX is shifting it all fine without some kind of aftermarket link? Did you have to mess with the b screw?

I'm contemplating upgrading my drop bar Litespeed MTB to R8000 shifters and the RX rear derailleur and the 11 speed 11-40 MTB cassette, so this is very timely!

Thanks so much

[John H.]

Correct- Here is my exact setup.
Open UPPER frame-
BB- Enduro Torqtite for BB30 cranks
Crankset- Easton road 34/50 with Power2max 4-bolt Shimano. Shimano Dura-Ace 9000 34/50 chainrings.
Front Derailleur Dura-Ace 9170 DI2
Rear Derailleur Shimano Ultegra RX (RD-RX805) DI2 rear derailleur
Cassette-XTR 9000 11-40
Chain- Shimano 900 1 link removed for 42cm chainstays (I would use full length on longer stays)

No extra road links or any pieces like that.
I did have to reduce the clutch tension on the rear derailleur. Without doing that, the derailleur did not like to shift up and down the 11-40 when in clutch mode.

I have it working great- Rode it 9+ hours road/gravel mix with 14k feet of climbing (4 hours Saturday/5+ on Sunday). Never missed a shift.

[NHAero]

Great info, thanks so much.

Correct- Here is my exact setup.
Open UPPER frame-
BB- Enduro Torqtite for BB30 cranks
Crankset- Easton road 34/50 with Power2max 4-bolt Shimano. Shimano Dura-Ace 9000 34/50 chainrings.
Front Derailleur Dura-Ace 9170 DI2
Rear Derailleur Shimano Ultegra RX (RD-RX805) DI2 rear derailleur
Cassette-XTR 9000 11-40
Chain- Shimano 900 1 link removed for 42cm chainstays (I would use full length on longer stays)

No extra road links or any pieces like that.
I did have to reduce the clutch tension on the rear derailleur. Without doing that, the derailleur did not like to shift up and down the 11-40 when in clutch mode.

I have it working great- Rode it 9+ hours road/gravel mix with 14k feet of climbing (4 hours Saturday/5+ on Sunday). Never missed a shift.

[dem]

I'm using the mechanical R8000 (non-clutch RX) version and it also works in that combination (50/34 crankset, XTR 11-40 cassette)

Small-small has almost no tension, and if you pedal backwards in the larger combinations it will skip gears as I had to screw in the "B" to take up some of that slack - but in general riding it is fine.

When (ever?) I redo it, I'd probably add the Wolftooth link to clean that up. I had similar issues running the RD-6800 and an 11-36 cassette. The Roadlink made everything better.

Just looking at the shape of the new MTB Di2 FDs it looks very tight - both the size of the big ring and the amount of room between the top and bottom, but I'd be keen to hear if it works. :)

[NHAero]

Just put an XT 11s 11-40 on my Anderson which has the Ultegra R8000 GS RD and a 44-33 chainring set. The B screw isn't close to all the way in and on the stand it shifts fine. Road test tomorrow! If it works well I'll swap out the 11T for the 12T I was running on the 11-34 HG800 cassette it replaced.

[NHAero]

And it works on the road too.

Just put an XT 11s 11-40 on my Anderson which has the Ultegra R8000 GS RD and a 44-33 chainring set. The B screw isn't close to all the way in and on the stand it shifts fine. Road test tomorrow! If it works well I'll swap out the 11T for the 12T I was running on the 11-34 HG800 cassette it replaced.