Could someone kindly confirm if the wire lengths I have are correct? This is from a Specialized rep but they are not matching up with what I've found online. This is for a 56cm frame 2016 Diverge which is near identical dimensionally to the Roubaix.

Downtube 1000mm etube (seems 50mm long?)
FD - 500mm (seems 100mm long?)
Shifters 2x 350
RD 700 or 750 (seems 100-150mm long?)
Battery to Juction B 1000mm (?)

Shimano has a pretty easy method for measuring what you need. First you need to know where your junction a and b are going to be. Are you going to use the more expensive 3 way cable on the bars or daisy chain with individual wires? In general take the measurement, go to the nearest even length rounding up. Add 50mm.

If your junction B is in the seat tube then measure the seat tube, length of seatpost - add together and add 250-300mm

Assuming an internal cable setup

If using an under stem Junction A, then 350mm from each shifter will work on a 44cm wide h-bar (this includes the 180 deg. loop of the cable at the shifter to allow some slack if the shifter gets knocked). I used 400’s as I sometimes use a 46 bar, so I had spare on the current 44. If using the bar end A Junction with the Y split, not sure.

It helps to yank off the crank and look at how your b-bracket shell is setup. Some have a large rectangular slot at the downtube, others might be on the seat tube side of the shell. It helps to confirm as that’ll dictate where you shove the B Junction, which in turns drives downtube cable, seat tube cable, plus F & R derailer cable lengths.

As BTW, I used a 300 cable off the internal battery, then connected to the EW-WU111 WiFi unit sitting in the seat tube, then 350 off that to the B Junction which sits in the downtube above the b-bracket shell. I saw this in a Di2 install YouTube and it keeps the WiFi unit out of harms way. Works on a carbon frame, maybe not aluminum.

It’s no issue going longer as all spare cabling just sits inside the frame out of harms way, where as you are kind of dead in the water if something is too short.

I'd agree with Steve once again. When I did my Domane, I made sure to use 350mm for the bars but everything else I upped a bit and measured the tubes themselves for giggles assuming that the wires inside the frame wouldnt bother me but the wires on the bars might since they would be under wrap and bulky. Sure enough I did a 1200mm from junction A to Junction B in my downtube and had plenty to spare as I did with some of the other wires. just measuring the chainstay, seat tube, etc. The only ones I wanted to be relatively sure of were the shifters through the bars to Junction A

Better cabling too long and hidden internally than cable too short.

Use a piece of string to measure against the actual frame.

Add a few centimeters to each wire.


-Tim-

Add me as another vote to go long and just hide the extra cable inside. You could have an extra meter of cable and it's not going to make a bit of difference on performance and you won't be able to tell on weight.

Conversely, having to run out to a shop and pay for another cable because you mis-judged by 50mm really sucks. I'm saying this from experience.

I went too short on some e-tube wires and ended up having to get longer replacements (luckily my boss has a box of spares so we traded) For Di2 always better to go a bit longer than shorter especially with internal routing. I haven't noticed any noise coming from wires in my frame on a Ti bike.

I've gone to a single wire from bars to frame.
I will use the junction box in the bar end or under the saddle.
Wires can be in any order. Too many variations, but much cleaner front end.

This one uses that coupling via the stem for all internal wiring. JBox is under the seat.
Venge Di2 Wires.jpg

This one uses the bar end J box - see left HB end. I wired this before the 9100 box came out. I now use the current flush bar end box. I also use it on a TT bike.
MASI Di2 2.png

~12.3 lbs here and not lacking any stiffness. Got it under 12 lbs now using a 1X.
MASI Di2.jpg

I like the wine cork as the bar end plug.

So to answer directly. Classic wiring has JBox on the stem and one in the BB (I get A and B mixed up).
Long is fine. You can get the ties to minimize movement, although things are pretty quiet anyway.
Battery to BB Junction B - the BB one is longer than needed. Are you putting in seat post?
I normally tape a loop into the wire on the battery and tape well, then slide down the seat tube. I can fish it out with a coat hanger. Seems Rube Goldberg - but that is a common pro method.

Longer is also better so you can pull A out of the BB slot.
Net is I think you are good, although the battery wires seem long.

The MASI wine was not as good as the MASI cork.

[MENTION=364302]Doge[/MENTION] thanks for the tips. Could you please post a pic and details for how you do junction box under the saddle? I'd love to do bar end junction box but it'd mean replacing my current carbon bar which doesn't have internal routing.

I prefer the EW-RS910 handle bar end j box A. But that Venge has the SES bars and it won't fit without cutting. I'm in the artic now, so no pics.
You need to have, or drill a hole in the top of your seat post. Some have holes already. Zipp ties between rails or hot glue to bottom of seat works.

JB goes in BB area.

From B to FD, RD, Front brake, JA. From JA to battery. So two wires unless running 1X.
From front brake, to left brake. Route inside bars

You could but battery some place else, but BB preferred.

I was hoping to do the bar end junction on my new bike but unfortunately and ironically the Pro Stealth integrated bars (subsidiary of shimano) still are not internally routed. When doing that you can also run straight up from junction B to your shifter and then connect the shifters together. Ah well back to normal set up for me!

Are there any alloy bars with internal routing? Specialized has them for their 2018 bikes, but they aren't available in the retail channel yet (and if history is any indication, probably won't be for a year or two).

OK, so with a seat post mount, you have to run very long cables (I see they make up to 1400mm) from shifters to the Junction A at the seat. Than standard stuff down to the B Junction at the b-bracket. Or use the EW-JC200 junctions to extend shorter cable.

I believe the pro vibe series has an internally routed alloy bar

Which Shimano bar do you have? I'd like to keep my Easton carbon bar for the vibration damping, but with the addition of the Redshift Shockstop I'm hoping going back to alloy won't make a difference. As robbyville said I think this one from Shimano might be the only alloy bar with internal routing on the market. Seriously considering it considering the price.

https://www.excelsports.com/main.asp...jor=1&minor=15

The seatpost mount would be ideal, but how many seat posts have holes going from inside the tube to the outside? Neither my Canyon VCLS 1.0 nor Specialized CG-R do. I won't drill a seat post, particularly carbon.

I believe the Easton alloy post I use has such a hole on the top, but begs the question as to how you get the e-tube wire past the battery in the post. Seems you’d have to modify the battery holder.

I would think at that point I’d rather use the bar end A Junction and get a bar designed for Di2 cable. I’m not retentive enough to want to spend the money for a different bar, but if it were a new build and I were buying stem and bar as new, I’d likely go this route.

That’s a great bar and price. In my case and got the Pro Stealth which is an integrated stem/bar combo. Since I paid a pretty hefty sum to have it painted to match my incoming frame I won’t be trusting myself to drill

Traditional routing for me right now!

Today was the first time I closely examined the old/traditional junction box setup on the stem as well the new bar end one. The old one is not that bad! With the bar-end jb you still have the wires coming out of the bars to go into the frame. Has me seriously questioning if I want to give up the carbon bars.

Agreed. The bar end is cool but the normal routing is just fine by me as well.