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Running a di2 wire through the mounting hole for the cable guide?

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Running a di2 wire through the mounting hole for the cable guide?

Old 12-31-17, 05:03 AM
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BazookaFro
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Running a di2 wire through the mounting hole for the cable guide?

New year, new bike. I have decided on a nice steel frame, with the major downside being that chances are it will not be di2 compatible. It seems easy enough to run most of the lines cleanly for everything save the battery. I'v thought of simply removing the cable guide on the BB shell, cutting the wire, and soldering it back together after threading it through the hole. But I don't take a whole lot of chances, and I have yet to find someone else who has successfully done this. would it be possible? any obvious issues? would the hole simply be too small? Keep in mind, I have no parts at this point.The frame hasn't even been released yet, just wanted to bounce an idea around. Maybe a slick external mounting option will come up. any input would be appreciated!

(this frame will have two bottle cages on the topside of the down tube, so the generic mounting option for the battery will probably* not be possible.)
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Old 12-31-17, 07:42 AM
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If its a steel frame, just drill a bigger hole in the bottom bracket. I build steel frames and drill drain holes in the bottom brackets of every frame. I've seen some builders make large decorative cutouts in the bottom bracket shells, so it won't effect the structural integrity of the frame.
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Old 12-31-17, 08:30 AM
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I think that the Di2 wire will be the size of a sewing thread inside it's plastic insulation. It'll be hard to strip the insulation without breaking the wire, and tricky to solder it.

Is this for the internal seatpost battery? I'd choose that over the external battery. It's hidden away from damage, and the charger is USB and very small, instead of a dedicated battery charger.

The Di2 plug on my rear derailleur is 5mm, the wire itself is 2.5mm. So you don't need a very big hole in the bottom bracket shell.

Have you seen the stick-on Di2 external wire covers?

~~~~~~~~~~~~~~~
The Shimano DI2 Dealer Manuals are essential -- easy to follow, step by step installation and adjustment instructions. Recommended for anyone that does their own adjustments, too.

pdf: dm-ul0001
from this shimano site: si.shimano.com


An image clipped from the pdf manual. there's a junction box near the bottom bracket.
And a wire to each derailleur, of course. If necessary, every wire could run externally, with just the wire to the battery inside the seat tube.

If you have external cables, the SM-JC40 has a mounting screw hole to attach to the bottom bracket cable guide. neat. Or the SM-JC41 is a tiny box for internal frame wiring.
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Old 12-31-17, 08:42 AM
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I've never read of anyone splicing a Di2 cable successfully.


If you don't have the frame yet....save yourself the ugly and eyesore and either drill the frame for grommets yourself, or get a frame made for Di2 to start.
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Old 12-31-17, 01:18 PM
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Hmm. I was trying to avoid drilling the frame all together... but it seems preferable to spicing the cable itself. would just enlarging that hole be the easiest option? If anyone is wondering, Black Mountain Cycles are finally planning to release a disc-ready frame, so I was planning to attach most of the wiring along the brake housing, which I assume would look pretty clean on its own. the only other frameset that comes close to what I want as far as tire clearance/geometry is from Fairlight, and it also has di2 routing, but chances are those wont be available till at least April.
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Old 12-31-17, 03:22 PM
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Is it this bike?



The rear brake hydraulic line runs down the left side of the down tube. The Di2 wire attached to it would work. But the exposed bottom bracket junction box might be a problem on a gravel bike, with mud and stones. And you'd have to carefully route and tape the rear derailleur Di2 cable, to keep it secure from the same mud problems. Perhaps there's room for an internal junction box, with 3 Di2 wires coming out the bottom bracket. But there may not be a large hole in the bottom bracket shell to the bottom of the downtube, where the box would sit.

You might contact Black Mountain and see what they think.

~~~~~~
I've used silicone repair tape to bundle cables cleanly. There's no adhesive, it only sticks to itself. A cleaner look than a series of cable ties.Don't try to spiral down the cable, just cut pieces long enough to wrap around 2x. Stretch as you wrap, and it works better, and press down too. The end occasionally starts to peel loose, but the tape usually stays together very well.

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Old 12-31-17, 04:13 PM
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Originally Posted by rm -rf View Post
Is it this bike?

The rear brake hydraulic line runs down the left side of the down tube. The Di2 wire attached to it would work. But the exposed bottom bracket junction box might be a problem on a gravel bike, with mud and stones. And you'd have to carefully route and tape the rear derailleur Di2 cable, to keep it secure from the same mud problems. Perhaps there's room for an internal junction box, with 3 Di2 wires coming out the bottom bracket. But there may not be a large hole in the bottom bracket shell to the bottom of the downtube, where the box would sit.

You might contact Black Mountain and see what they think.

~~~~~~
I've used silicone repair tape to bundle cables cleanly. There's no adhesive, it only sticks to itself. A cleaner look than a series of cable ties.Don't try to spiral down the cable, just cut pieces long enough to wrap around 2x. Stretch as you wrap, and it works better, and press down too. The end occasionally starts to peel loose, but the tape usually stays together very well.
Yup, thats it. I've seen others run the rear derailleur under a chainstay protector, but you might be right about the junction box. I'll try to reach out to BMC, not sure how well it will work out, but I guess I won't know till I try.
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