Di2 Hydro Compatability

[Clean39T]

So, I think the official word from Shimano is that Di2 hydro shifters (previous generation) are compatible with the mountain groups, but only if you are using mountain front and rear, or 1x, and can't be used road front and mountain rear. Is this typical Shimano conservativeness, or does it really not work?

I have a gravel/cross bike inbound with Di2 hydro shifting an XT rear and 1x up front, but just bought a 6870 FD and am wondering if I need to find a 6870 GS for the rear to use with a Wolf to get 11-36, or if the XT will work. It would be nice to keep the clutch out back and still use the 36/46 up front...

EDIT:

The internets have my answer...firmware prevents mixing the two.

http://www.gravelcyclist.com/bicycle...road-shifters/

It looks like if I want to keep the Di2 setup and the clutch/wide-range out back, I'd have to go to a XT FD and get creative with my crankset choice.

Seems like it would easier to just either: 1) sell the Di2, switch to mechanical, and use the J-Tek with the XTR rear I have, or 2) go the 6870 GS rear and lose the clutch...

[cachagua]

Sell the Di2, switch to mechanical...

Winner.

About half the people I know who use electronics are really enthusiastic about it. About zero who don't use it say they miss it. Tells me all I need to know.

In any case -- do we really want to reinforce behavior like this on Shimano's part? Paying them to make our bikes more clumsy and finicky and machine-dependent (instead of ingenuity-dependent) to set up and ride the way we want just seems crazy.

[Clean39T]

Originally Posted by cachagua

Winner.

About half the people I know who use electronics are really enthusiastic about it. About zero who don't use it say they miss it. Tells me all I need to know.

In any case -- do we really want to reinforce behavior like this on Shimano's part? Paying them to make our bikes more clumsy and finicky and machine-dependent (instead of ingenuity-dependent) to set up and ride the way we want just seems crazy.

If I do that, it means switching to BB7 brakes (cheap and I have them on my shelf), or some other mechanical disc, since I don't really want to shell out for mechanical hydro shifters...unless they are Campy H11...and I don't have the scratch for that on this project.

If I can find a 6870 RD in GS on the cheap, that'll work for now.

[foo_fighter]

HyRds are a pretty good compromise. Much better than BB7s...not quite as good as full hydro. Juin Tech X1 / Yokozuna Motoko might also work.

Originally Posted by Clean39T

If I do that, it means switching to BB7 brakes (cheap and I have them on my shelf), or some other mechanical disc, since I don't really want to shell out for mechanical hydro shifters...unless they are Campy H11...and I don't have the scratch for that on this project.

If I can find a 6870 RD in GS on the cheap, that'll work for now.

[DrSpoke]

I went through the same thought process about a year ago. I was dropping the chain a lot on my Shimano hydro/mechanical set up. I was planning to switch to Di2 and wanted a clutch RD. The problem is that the down tube on my Ridley X-Trail is not round and Shimano doesn't make a mtn FD to fit a braze-on so there was no way to attach a mtn FD. In addition, they are designed for a smaller diameter chainrings. So my choice was 2x w/Ultegra GS or 1x w/XT.

I ended up going w/Ultegra and am very pleased w/the result. I'm not sure what was causing the dropped chains. As they were coming off the bottom of the chainring on rough descents, I assumed it was chain tension - hence the desire for a clutch RD. Regardless, when I went to Di2, I also switched to an Ultegra crankset and the problem is gone - thankfully.

I would highly recommend Di2 for off-road use. The ability to shift instantly under power comes in very handy in soft sand, sudden ascents or shifts mid-climb. Myself and most of my friends are running a standard compact 50/34 up front and a SRAM 11-36 11-sp road in the rear w/no issues. None of us have needed the RoadLink though I have one just in case.

If you want more than 36t in back then a mtn RD is probably the way to go. For me, that would mean mechanical so I could use the road FD. Though, now that I think about it, my friend just bought a used Ridley w/a 40t rear and Di2 I so need to take a look at how that is set up. I'm pretty sure it's 2x but could be 1x.

[DrSpoke]

If you decide to go hydro/mechanical, I have a pair of levers - 685s. No calipers or lines.

[DrSpoke]

I've also got a Niner RLT Steel set up with SRAM Force 1x w/a 10-42 cassette. It was delivered w/a 42t ring which I immediately switched to a 38t. This setup works great for all dirt or mostly dirt rides. But it doesn't have quite the gearing range for either all road or mixed road/trail rides. That said, I've have used in for road centuries as well as big road climbs like Palomar Mtn. It does, of course, have the larger gear spacing associated w/1x systems.

So, depending on your intended use, I'd try the bike for a while as delivered. You may like it. If not, you'll have some time to decide which direction you want to go next.

[John H.]

You are correct in that you cannot mix XT/XTR Di2 with road derailleurs for a 2x setup.
You either have to run mtb front and rear, or road front and rear.

GS 6870 works great with a SRAM 11-36 cassette. I have this exact setup. No road link needed.

I have heard of people running the mtb derailleurs with a 34/50 chainring road setup. I could not do this because my gravel bike has a braze-on front derailleur hanger. All of the mtb front deraillluers are clamp-on or direct mount.

Originally Posted by Clean39T

So, I think the official word from Shimano is that Di2 hydro shifters (previous generation) are compatible with the mountain groups, but only if you are using mountain front and rear, or 1x, and can't be used road front and mountain rear. Is this typical Shimano conservativeness, or does it really not work?

I have a gravel/cross bike inbound with Di2 hydro shifting an XT rear and 1x up front, but just bought a 6870 FD and am wondering if I need to find a 6870 GS for the rear to use with a Wolf to get 11-36, or if the XT will work. It would be nice to keep the clutch out back and still use the 36/46 up front...

EDIT:

The internets have my answer...firmware prevents mixing the two.

http://www.gravelcyclist.com/bicycle...road-shifters/

It looks like if I want to keep the Di2 setup and the clutch/wide-range out back, I'd have to go to a XT FD and get creative with my crankset choice.

Seems like it would easier to just either: 1) sell the Di2, switch to mechanical, and use the J-Tek with the XTR rear I have, or 2) go the 6870 GS rear and lose the clutch...

[bewheels]

Originally Posted by John H.

You are correct in that you cannot mix XT/XTR Di2 with road derailleurs for a 2x setup.
You either have to run mtb front and rear, or road front and rear.

GS 6870 works great with a SRAM 11-36 cassette. I have this exact setup. No road link needed.

I have heard of people running the mtb derailleurs with a 34/50 chainring road setup. I could not do this because my gravel bike has a braze-on front derailleur hanger. All of the mtb front deraillluers are clamp-on or direct mount.

I have also run the Sram 11-36 with the GS 6870. It works fine provided your drop out is up to the Shimano spec. In other words, the type of rear drop out can play a role in whether you can properly adjust the b-tension screw to accommodate the 36 cog.

[Clean39T]

Originally Posted by bewheels

I have also run the Sram 11-36 with the GS 6870. It works fine provided your drop out is up to the Shimano spec. In other words, the type of rear drop out can play a role in whether you can properly adjust the b-tension screw to accommodate the 36 cog.

Good info. That's the direction I think I'll take things to start. 36/46 and 11-36 sounds like a very nice wide range that won't be too awful for gaps in the back.