Goldrush

Shimano has announced XTR Di2 for mountain bikes, including triple front chainrings. Will this work for tandems?

Shimano XTR Di2 - Electronic shifting comes to mountain bikes - BikeRadar

mstyer

With an available 11-40 cassette, who needs a triple? Use a DA Di2 double up front and an XTR rear to get a 2x11 with a really wide but evenly stepped gear range.

https://www.gear-calculator.com/#KB=3...5&UF=2130&SL=2

2frmMI

You beat me to it Goldrush! I saw a different news report, however:
Shimano Unveils XTR Di2 M9050, Mountain Bikes Go Digital, Lose a Shifter

As an Ultegra Di2 user, with K-edge modified rear derailleur, I can say this is VERY attractive. I think this can transform tandem gearing and shifting. Imagine an 11-40 cassette and a triple crank! Only limitation I can think of is the higher gearing, where I always loved my 54 X 11. I did not see if there is a limit for chainring sizes. 54-42-30 might be nice...

2frmMI

I agree. And the synchronized shifting is also VERY attractive, though I'd have to try it to be sure.

waynesulak

The idea of one shifter with synchronized shifting has possibilities but on rolling terrain like ours I think it also has some downsides. Sometimes I intentionally like to cross chain a little more or less depending on upcoming terrain. For example I may cross chain in the small ring on a double a little bit more at the bottom of a hill when I can see the hill up ahead will mean leaving the big ring just after shifting up to it. As long as you have multiple rings up front there will be some advantage to the rider anticipating upcoming terrain and planning ahead.

Great to see what appears to be a triple FD in the electronic shifting area. I hope that the system can be adapted to the road triple used by most tandem teams.

2frmMI

I don't recall if you are currently running Di2. I would have had this same opinion before our new Di2 bike. Shifting is SO precise and reliable, that I don't need the kind of pre-planning I used to apply. I'm guessing the electronic synchro will work so well that your only consideration will be "time to shift?". All speculation right now, of course.

rhino919

Take a look at Lennard Zinn’s first ride review of Shimano XTR Di2 on Velonews. He didn't think he would like sequential shifting, but turns out he does. YMMV.

Goldrush

[QUOTE=mstyer;16805921]With an available 11-40 cassette, who needs a triple? Use a DA Di2 double up front and an XTR rear to get a 2x11 with a really wide but evenly stepped gear range.

After over a year of trying, I haven't been to get the XTR rear shifter to work trouble free on my 11-34 10 speed. 11-40, no thanks.

2frmMI

I used mechanical XTR for a long time with 11-34 and 12-34 9 speed with absolutely no issues. I just installed 11-36 with the Ki2, and it shifts flawlessly. If Shimano sells it for 11-40, I'd put money on it working extremely well.

Goldrush

[QUOTE=2frmMI;16806182]I'm glad you have a trouble free system, but Shimano sold the parts on my bike also and several "ace" mechanics haven't been able to get it to work without endless trimming. The first problem was someone unknowingly installing one Shimano's "great idea" of a directional chain backwards. After correcting that the bike shifted very well on an 11-28 cassette this winter. Now as I return to the hilly midwest and install the 11-34, my problems start all over. I'm currently awaiting the arrival of a mid cage Ultegra rear shifter and an 11-32 cassette.

I might note that my previous tandem had your same setup (9 speed) and worked perfectly. I believe part the problem is the with the 10 speed system.

mstyer

Did you replace the chain at the same time as the cassette?

[QUOTE=Goldrush;16806217]

waynesulak

I hope you are right. Shimano seems to usually get their products to work well - eventually. Not usually with ver 1.0 however. There first STI triples shifted poorly but now not so bad. Likewise I am glad I don't have lots of money tied up in the now orphaned original Dura Ace Di2 on my bike. The newer modular system that started with Ultegra looks a lot better.

LastKraftWagen

So, who has Shimano Cycling's number and the savy to get out of them whether the XTR FD will work in the road setup?
(The only number I can find now is the fishing division, and they didn't transfer me to cycling after two attempts)

twocicle

With some caveats:

#1 - 11 spd only.

#2 - FD cage arc issue?
Mtn bike chainrings are very small and the FD is designed around the arcs of these. The largest XTR configuration is the 40/30/22 rings.

#3 - Will these 9050 components work with current Di2 E-Tube road shifters or only the new single 9050 Syncro shifter?

Bad1

Shimano rep was thru town about 3 weeks ago, I was talking to the bike shop owner who also a CoMo dealer who was involved with my new Macchiato Dura Ace DI2 build about drilling the Rep about the Mtn. DI2 setup, would it cross over to a road bike Application. Few days later after the rep was gone I ran into The shop owner and talked about what the rep had to say. He said according to the rep that everything would switch over from cassettes, derailleurs, front and rear and be able to plug & play, Guess we'll just have to wait-and-see, it will be one of those show me don't tell me!
BTW Mid-2015 release is planned.

LastKraftWagen

1. Provided the road and mountain components are interchangeable, switching to the ten speed should be (the way I understand it) a simple matter of using a 6770 RD... In the road versions, the RD swap is all that is needed to switch the electronics between 10 and 11 speed.

2. True... Wonder how long it will take for someone to rip the XTR apart and fit a road cage? The swap on the rear seems simple enough. Probably beyond my blind fingers capabilities, and my bike and both FDs are currently at the LBS so I can't check it...

3. The way I've read it, you can go either the syncro/single shifter option or reprogram it for a conventional 2-shifter setup. Wonder if the syncro could be programmed into a road setup with XTR derailleurs, maybe even into a climbing shifter?

So Twocicle, are you considering a left-side timing set up? Of course this new option comes out as so many of us have fought through the double front set up, but fortunately before my new bike build...

LastKraftWagen

Is there a typo herein, or is there really a 11-40 cassette?

Never mind, found it.

Also read that while the 11spd road cassette requires an 11spd compatible hub, the new XTR 11spd fits a 10spd rear hub... Guessing the spacing between cogs is different which may raise road/off-road compatability issues if mixing RDs and cassettes. New cassette is supposed to be designed for roughly 10rpm cadence changes between gears, but the first 7 cogs are the same as on the 11-36 and I don't have the same experience on my set up.

The new XTR FD does have an insanely small cage, and 40T may be about the largest ring.

Wonder what the wrap is on the new RDs... 40-30-22 chainrings (18T) and 11-40 cassette (29T)... 47T?

mstyer

They accomplish the mountain 11-speed on a 10-speed freehub by offsetting the largest cog into the spoke's airspace. By the time the spokes reach the diameter of a 40 tooth cog, they're inboard quite a few millimeters.

akexpress 

I will be a early adopter of the new cassette. As we run DI2 now with compact cranks 50/34 and a 11-36 cassette I will move up to a mid compact chainring 11 speed set 52/36 and use the new cassette and expand our range a bit and go to 11 speed this way. I have not moved to 11 speed at this point is because I can't get free hub bodies from Chris King to fit our hubs and I have two sets of 10 sped wheels. I will try an Ultegra 11 speed rear derailluer with my K-edge modified cage and see if it works if not get the XTR derailleur. The shifters don't matter as they are only switches. I just completed the DI2 conversion of my wives Cervelo tri bike today and it is always amazing how well everyone of the DI2 bikes shifts with almost no effort to dial it in and then it just stays that way. I have now done 4 internal conversions and don't think I will ever go back to mechanical and would certainly consider it for our mountain bikes in the future. By doing everything internal it sure makes the bikes very clean looking.

waynesulak

If I wanted 11speed on my 10 speed tandem wheels it seems the spoke angle is sharp enough that grinding a 1-2mm off the aluminum cassette spider would allow enough room for a road cassette to slide inward and still work.

Dean V

That is what I did to fit an 11-32 11sp cassette. Needed 2mm turned off from the inside of the spider.

ebnelson

We are using mid-compact 52-36 chainrings with the Ultegra 11-speed mid cage derailleur and the 11x32 cassette. We are quite happy with this gearing on our bike which is a lightweight carbon road tandem. On the steepest climbs around our Boulder, Colorado home we are working pretty hard to spin up, but are able to spin. The only challenge is that the internal battery needed to be updated to the latest firmware to work with the internal battery. We were using DA before "upgrading" to the Ultegra derailleur.

gsa103

Looking at Zinn's comments, the sequential shifting allows a fair amount cross-chaining. The shift points are asymmetric depending on if you're upshifting or downshifting, this should make it very easy to accomplish what you want.

For example, approaching a hill, downshift until you shift into the smallest front ring, then upshift 2-3 times, until you're in the same gear ratio you were before, now with the chainring where you want it.

waynesulak

I think that I would like sequential shifting if the shifting is so good that it almost disappears so that you don't notice if the shifts are up front, in back or both.

On the other hand doing what you mention would annoy me. Having to over shift down a couple gears (stoker complains of high cadence here) just to get it in the small front ring then shift back up to get to the original ratio is really working way to hard to get technology to do what can more easily be done with a the existing Di2 or a mechanical system that is shift the FD alone.

I guess this is like an automatic vs standard in a car. It depends what you like to drive. I can see sequential full auto bike shifting keeping it in a set cadence range in the near future. Pretty neat but I don't know if I want to give up picking my own gears.

akexpress 

I don't think this is how it works It will shift both derailleurs at the same time as needed to sequentially shift. As DI2 shifts are almost instantaneous already this should be a really slick smooth system.