I have the new Giant Trinity Advanced Pro 1 and the junction box is integrated nicely in the top tube storage box. I did consider what you mention though but can't find that junction box available anywhere online to buy. I do plan on trying it though at some point since I have to get one anyway for my road bike.

Thanks for the reply. I have the Giant Alpecin team edition TT frame, so it doesn't have the top tube storage box. It does have a cavity to put the junction box just behind the stem, but accessing it requires that stem to be removed.

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I built up a TT bike 3 years ago and stashed the A junction in the frame. Here is what I did for charging purposes. Take your charger and cut off the end of the wire that plugs into the charging port on the A junction. Now get another di2 e tube wire and an internal 4 port junction box (the part name escapes me at the moment but I am sure you know what I am talking about. let me know if not) Now cut the extra di2 wire in half. Take one half and solder that to the battery charger, go visit your local hobby shop if you need help, they will solder it for stupid cheap probably.
Now you have a di2 charger with a di2 tube end on it instead of the little prong end that would usually go into the A junction. Take new charger and junction box, unplug your rear derailleur, plug the RD di2 cable into the new junction box, charger plugged into the junction box and now your battery is charging.

There was no good way to check the battery level very easy with this route, so I would just make sure I would charge it once a month and made sure I had the indexing really good before I buried the A junction!

Does the TT frame have the 2-part 'beard' directly underneath the stem? If so, it is only 3 (or 6) screws to remove 1 (or two) of those pieces. I bet you could pop that sucker off in about 30 seconds with practice. Annoyingly, you'd also have to remove those pieces to check the charge and trim the derailleurs too

Oh I forgot you need one extra e tube wire to go from junction back to RD to complete the "circle"

I have one of the junction boxes for use on culprit development and it does not fit in the back of the 2 different extension bars I have in office.

Joshua

Thanks for the suggestion, but as dfroelich mentioned, the disassembly of the front end is probably too easy to justify modifying a charger. I'll keep in the back of my mind though!

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But judging from the junction box, does it seem doable to you to trim away some of the casing to make it fit? I have to make do with pictures I find online, I haven't actually held an EW-RS910 junction box in my hands.

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well if you change your mind, i might be willing to trade you mine that I dont use anymore (the battery charger with the e tube connection on the end) for a couple of your products.

After spending some time with my bike with a poorly accessible junction box, I bit the bullet on trying the EW-RS910 in an aero extension, so I thought I'd report back on how that went down.

As it turns out, the EW-RS910 I received fits into the extensions I have without modification. The junction box is 19mm at its widest, while all my extensions are 19.5mm internal diameter. I used some white Teflon tape to fill up that remaining space and have the EW-RS910 sit nicely in the extension.

I'm left to wonder if there have been bigger versions of the EW-RS910 with a 20.5mm max width, or whether this has to do with it sitting perfectly centered (as it is not precisely symmetrical).

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Really comes down to extension tolerance. Some brands have thicker walls of extensions. Thus not fitting. Others are thinner

Each brand will have diffetent acceptable tolerances.

I imagine you are right in saying that not all extensions have the same inner diameter. However, I have 4 sets of extensions with an inner diameter of 19.5mm: Giant Connect alloy, Zipp Vuka alloy, Zipp vuka carbon, and Profile Design alloy.

But the most noteworthy part of my feedback, in my opinion, is that Shimano claims a required 20.5mm inner diameter for the EW-RS910, whereas the one I received measures out at 19mm max width.

So in any case, I've read about people trimming down their EW-RS910 to make it fit. So anyone attempting this solution should at least accept the possibility of sanding down the junction box, but it's also possible you may not have to at all. Perhaps people who have had to modify their junction box could share the inner diameter of the extensions they fit them in.

EDIT: incorrect phrasing

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Where did you run the wires if you put junction A in the extension?

You referring to this?


http://a68.tinypic.com/2qvyzr5.jpg

On the Trinity with the standard extensions at least you'd route the cable out through the bottom of the extension and directly into the basebar and through into the stem assembly through the same hole that the brake cables are routed.

I've literally just converted mine and for the time being have put the A junction in the bento. Ideally I don't want to keep it there and will be looking to fit the 910 A junction or hide a 3 or 5 port behind the covers. I'll probably end up fitting the 910 and fit the ST 6871 gear/brake levers at the same time, but that can wait till next year!

As Triheaven mentions, you run the cables through a hole somewhere along the length of the extensions. Depending on your extensions you might have to drill those holes, but there are some out there which are pre-cut. You only end up with a setup issue if you'd normally run your Di2 cables out the rear end of the extension.

Indeed, that's the setup. There's multiple ways to go about routing it further, what types of connections and junctions you use in addition, but for me the most important reason to have this is to get easy access to the di2 charging port and the button in order to put the junction box in wireless mode.

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