[Closed] More DI2 questions

So all you've got are the mechs and levers?

Guessing at an internal battery set up you will need -

6 wires (2 levers to external junction box A, one junction to bottom bracket, one from bb to battery, one from bb to front mech, one from bb to rear mech), a 3 or 5 port external junction box A under the stem, a bottom bracket internal junction box B, an internal battery and a charger.

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External battery but internal wiring.

You'll need

2 x approx 300mm cables for shifters to external jb at stem
1 x approx 900mm for Jb to splitter box in frame at bottom bracket
1 x approx 500mm for rear mech to splitter
1 x approx 250mm for front mech to splitter
1 x approx 350 for battery to splitter

External battery and cradle (although I would go internal battery if it'll fit)
3 port JB for stem
4 way splitter for frame near b/b
Battery charger

And is it all compatibles?

😕

all except 10s dura ace is compatible with each other, although due to Shimano firmware updates you're best to stick with 10s shifter/mech together or 11s shifter/mech together, don't mix them.

oh, and i'm pretty sure you can't charge an external battery through the stem mounted junction box, you have to remove and charge.

You all forgot to mention the infinite patience requied to set it all up (threading the wires etc) or the money to pay someone else to do it!

Thanks all.
Will get everything ordered.

GeeTee eh? it's a doddle. if you can read instructions and thread a normal gear cable, you can fit Di2. except you only have to do it once as you'll never have to thread another cable if it gets dirty or worn.

blazin-saddles +1

Took about half an hour to fit all the wires inside my frame. You can't do it wrong, it's all modular. I have the ANT+ dongle thingy in the BB shell and the climbing shifter plugged into the LH shifter.

Just had quick look and there is a internal or external junction box, where do you fit the internal box?
Cables can go inside the frame, but there is not an opening for a small box?
I think I'll have to get the external one to fit under the bb.
And all those bits are not cheap, it adds up quite quickly.

How big is the down tube of your frame, all of my Di2 builds have the internal JB inside the down tube near the BB shell. External JB only needed if the bb shell is 'sealed' i.e. just a tube.

The sundry items normally add up to nearly as much as the mech/shifters.

The sundry items normally add up to nearly as much as the mech/shifters

+1

and if you go for the external battery you may have issues that require the programmer...which is why I reckon the internal battery and combined charger/programmer is a better deal...

Agreed.

ok , just realized i had a proper thick moment . I could not see a way to stick junction box in frame but it is quite obvious that by removing the bb , there should be plenty of room down there ......

will have to investigate battery options further .

ok , so i have nearly all the bits , only missing the stem battery junction .

is it wise to test it before fitting to the bike or is it going to mess it up ?

Took about half an hour to fit all the wires inside my frame.

You've not tried wiring up time trial bars and a frame that wasn't designed for Di2 😉

Got to say though, it is all pretty cool. Once you know that a junction box is just that, and you can pretty much plug anything in anywhere as it's all on a bus, it's brilliant. I think I've about 4 B junction, 1 A junction and a load of cables in my installation.

I have the ANT+ dongle thingy

Oh just ordered one of these. What do you use it for? My A junction is in the frame so getting it mostly to see the battery level, though might be pretty cool to be able to see stuff like gear selection too.

is it wise to test it before fitting to the bike or is it going to mess it up ?

Usually a good idea to test it while it's all still fairly accessible. I'd already fitted most of mine but could still get to the important bits just in case.

ok great thanks .

finally got all the bits last week .

wasnt too bad fitting it . 1 or 2 of the wires were on the short side so had to think carefully where they went .

took it for test ride this morning , and 102km later , I am very impressed .
so much easier than mechanical , especially the front .

The first time I built a bike with Di2 it felt like I was saying a sad and tearful goodbye to my trusty Park cable cutters.

After many years of trusty service on brake and gear cables, then being relegated to only cutting and crimping gear cables since the agent of disc brakes, they stayed in the toolbox for the entire build.

Sad times.

I'm yet to be convinced by it on a mountain bike though - I can mash through 4 gears a lot more quickly in a sudden situation with a mechanical thumb lever than my cross bike (with XTR di2) will shift even on very fast mode.

Agreed, not sure if it would be as good on the mtb, especially with 1x transmission.

Only regret I have is the 3 port junction box, should have gone for the 5.

My A junction is in the frame so getting it mostly to see the battery level, though might be pretty cool to be able to see stuff like gear selection too.

Yep, same, general cool stuff. My personal favourite is being able to change the Garmin screen from the buttons in the STIs, plus all the extra stats I can now geek out on.

Gee - I've got 2x XTR Di2 on one bike and 1x mechanical Di2 on another. The Di2 is way faster, and more accurate - especially if you need to dump more gears than the mechanical can manage in one stroke.
I reckon there's more advantage to Di2 off-road than on.