1x11 Di2 Project

[jamescbdunn]

Hi All,

I'm cobbling together a concept in my mind, and trying to determine if it is viable.

I will soon have a CX/Monster cross Soma Wolverine running single speed w/ TRP Hylex brakes. I'd like the option of bringing gears in the future, with a way of swapping from single speed for the commutes/around town to geared for touring, gravel grinding or monster-crossing type stuff.

It looks like Di2 would be a straight forward way of easily* doing this. Swap a wheel, swap a chain, screw in a derailleur and plug an etube wire. Bam, geared. Reverse the process, bam, bombproof commuter.

Inspired by this post, http://weightweenies.starbike.com/forum ... 4&t=132365,
I'm imagining I can get away with:
- a Di2 climbing shifter,
- a SM-EW90-A 3 Port Di2 Junction Box,
- a seatpost mount battery and
- a derailleur (hopefully something cheaper than the XTR comes along, I'd make do with an Ultegra Di2 in the mean time)

All going well,
- the climbing shifter would run along the top tube to the junction box,
- the junction box would be mounted to the saddle,
- the battery would be in the seatpost and
- the cable for the derailleur would run down the drive side seat stay or back down the seat tube and out near the Bottom Bracket if possible?


So, any feedback would be very welcome. Am I in fantasy land with this idea?

Thanks in advance.

[MattyK]

Sounds good. Will the ultegra RD work with a wide cassette?

Also I assume you're aware of this kit:
https://www.trpbrakes.com/category.php? ... &catid=188" onclick="window.open(this.href);return false;

[jamescbdunn]

Wow, I actually was not aware of that. Thanks! Makes it feel like slightly less of a kludge.

The Ultegra RD would be a stop-gap (if I get impatient to test it out).

My main concern is whether I need more Di2 parts to make this work, i.e. another junction box or something like that? I'm really unfamiliar with what's required to make it all "tick".

[Duck!]

In concept it should work, as single shifter, derailleur & battery will be fine with the 3-port junction. My only misgiving is that the distance from shifter to junction may exceed the length of a single cable. You may need a second junction + cable to get the length you need.

[jamescbdunn]

Thanks, I knew it all seemed to simple. A bit of googling indicates that a part theoretically exists to function as an extension, http://www.amazon.com/Shimano-Di2-EW-79 ... B004JKIHU2, but hard to say if this part can be purchased by itself or not.

Thanks again!

[Duck!]

Disregard anything 7970 series, it is completely incompatible with everything else.

[jamescbdunn]

Good point. Junction box it is then!

[Duck!]

I'd go shifter into main junction (EW90) under the stem, main cable down to a JC40 (external under BB) or JC41 (internal) junction, then cables to battery & derailleur.

[jamescbdunn]

That's the most sensible solution, and likely where I'll end up.

I was imagining something almost invisible. I'll still try to get get a junction box under the saddle, and see if I can get a seat post that will allow cables to run through it.

Who knows, SRAM Wireless might come in to play before I get around to assembling this, and make this plan redundant.

[Duck!]

As far as derailleur options, Ultegra will handle a cassette with up to 32T big sprocket, any more will be the domain of XTR, at least in the short term. Nothing has been mentioned regarding XT Di2 at this point, but if it is in the works, don't expect to see it for at least another year (based on introduction delay of Ultegra Di2 vs mechanical when first released a few years ago).

[jamescbdunn]

Still haven't got around to building this adventure bike yet, but the cabling plan just got significantly cleaner.

https://youtu.be/0_F2t2zshrM?t=260" onclick="window.open(this.href);return false;

The Shimano Pro Tharsis XC stem will let me mount the battery in the steerer, leaving just one cable to run back to the rear derailleur.

I'll post photos when/if this build eventuates.

[Duck!]

Due to the length you may still need a lower junction acting as a joiner for a two-piece RD cable.

[Ross]

Have you been to http://carltonbale.com/shimano-di2-ever ... d-to-know/" onclick="window.open(this.href);return false;? Di2diy on there does custom stuff for Di2 and sells on eBay

[m@]

I have nothing much useful to add, just stopped by to say I love the concept! Will follow with interest.

[jamescbdunn]

I've been running it as a singlespeed beast for the last few weeks, 44x16 w/ Gatorskins for commuting and 32x18 w/ 40mm WTB Nanos for a bit of singletrack fun. Loving it so far!! The flexibility really helps with with the N+1 factor, 1 bike for 4 different purposes. (Commute, CX, Offroad + Touring)

Version 1 of the Di2 set up is complete, I ended up cobbling together an external battery, Hylex shifters w/ satellite shifter via adapter, and a 10spd Ultegra derailleur. Photos to come.

[TonyMax]

If the cable length restriction is just due to what is available (i.e. they don't make long ones), and nothing to do with voltage drop or other limitations of long cables, you can join (and therefore extend) Di2 cables using a soldering iron and some heatshrink. Just get a length of the appropriate somehow two core cable and away you go.

[jamescbdunn]

Thanks Tony, that's what I thought.

In the end, I sourced a 1.4m eTube wire which is more than enough.

[softy]

Done something similar, but with aero handle bars and a thumb changer on a roadie.

Dumbs down the changing, so simple. The aero bars are really comfy and for city riding the 39t 11t is good for about 45 km. So good enough for the city PSPs. Mine is only a 10 speed though.

enjoy, sounds like a great project.

[Duck!]

One thing which I didn't mention before, mainly because you ruled it out 'cos of the cost of XTR, for future developments be midful that due to the different programming there's a possibility that the MTB RD will not talk to the road shifters. Shimano generally say things don't mix between road & MTB when they often do, but on the electronics I simply don't know, 'cos I haven't been able to test it.

[jamescbdunn]

Ok, the photos are finally here. Not great quality, but good enough to get the gist.

http://imgur.com/a/n5E7L

This project isn't done yet, still to come are:

- The Pro Tharsis XC Stem
- The steerer tube internal Di2 battery
- Better cable routing to the rear derailleur
- Better rear derailleur solution. Initially running with this 6770 with a Lindarets RoadLink to 11-36 cassette (still to be tested if this works). If Chain retention is an issue on rough roads I might move to XTR or XT or something down the road.[/list]

[softy]

Very cool!

[jamescbdunn]

In the spirit of continuing updates, I installed the Lindarets Roadlink http://www.lindarets.com/roadlink/ this morning. Now, I have an 11-36 cassette paired with the Ultegra 6770 Di2 derailleur. Amazingly, it just works.

Chain tension is pretty loose in the 11t, but it gets up to the 36 no probs. I suppose I could possibly squeeze an 11-40 in there, but no need at this stage.

Also, credit to Duck! for his thoughts re:Di2 cable length. the 1400mm cable is "Exactly" the right length... Slightly longer stem, top tube or seat stay, I'd be out of luck.