Generator Wiring Through A Fender

[Peter P.]

Long story short; the rear fender cracked on my commuter bike. I run a seatstay mounted generator for the lights and routed the headlamp wire on the underside of the fender.

The fender had a squarish profile, and the wire was tucked into the inside corner of the fender and secured in place with silicone adhesive.

I have a couple problems.

1. I have a replacement fender but it has a rounded profile. I can't think of a way to run the wire in a relatively straight, clean fashion on the underside of the fender.

2. The silicone adhesive seemed to collapse the side of the fender, moving it closer to the tire, reducing side clearance. Any suggestions on how to adhere the wire to the under side without that collapse happening?

In the attached photos, you should be able to see the differences between the collapsed side of the fender and the normal, left side of the fender.

Thanks!

[CNY rider]

I can only wish you the best of luck with that.
I often look at the internal wiring on my Mariposa and marvel at the elegance and how difficult it must have been to achieve.

[dlui]

to start from scratch, I would prop the tire side of fender open with sticks, cardboard or whatever is handy. Lay the wire down and the silicone goop. the sticks should minimize the movement of the fender sides as the goop cures. YMMV

[unterhausen]

I just run the wire down the frame and out the fender strut. I have been using Gorilla repair tape, and it works great, you barely see the wire. Berthoud fenders have a gutter to run the wire in, if you keep the wire under tension it needs very little persuasion to keep it in the gutter.

Your original fenders have a conductor molded in, I believe.

[JAGI410]

I use short 1" pieces of heat shrink tubing, glued to the fender with Goop. Works well and is easy to remove. I use the same technique on the inside of the fork leg to hide the wiring from the hub.

[Black Dog]

I just run the wire down the frame and out the fender strut. I have been using Gorilla repair tape, and it works great, you barely see the wire. Berthoud fenders have a gutter to run the wire in, if you keep the wire under tension it needs very little persuasion to keep it in the gutter.

Your original fenders have a conductor molded in, I believe.


And there is your solution.

[Peter P.]

I just run the wire down the frame and out the fender strut. I have been using Gorilla repair tape, and it works great, you barely see the wire. Berthoud fenders have a gutter to run the wire in, if you keep the wire under tension it needs very little persuasion to keep it in the gutter.

Your original fenders have a conductor molded in, I believe.

Yes, but that conductor is for ground, not +voltage.

I might try the Goop and heat shrink tubing. If I do, I'll report back.

[unterhausen]

that makes sense about the conductor, never tried to use it.

One tip with the tape is to use gloves so that you don't get fingerprints in it. I have found gluing to a fender to be highly unsatisfactory, but then again, I'm no J.P. Weigle

I thought about heat shrinking the wire to the strut the last time I did that.

[DerekB]

How about copper tape instead of the wire? I have a roll I bought somewhere, don't remember but maybe McMaster or electronics supply.

[palincss]

You could glue that wire right on top of the fender. It's visually busy enough on top of an SKS fender that you won't really notice it. I had my Longstaff set up that way for years.

Or, if you want real elegance, you could replace those SKS fenders with Honjo or VO metal fenders for not much more money than the SKS, and then you could run the wire under the rolled edge of the fender.

[11.4]

Get some of the stick-on housing for Di2 wires -- it has a little channel inside for the Di2 wire and you just cut it to length. It actually looks rather elegant on top of the fender, like a fin on an old Cadillac.

I've tried installing wires using heat-shrink tubing, and you can get 1/4" GB heat-shrink tubing that reduces to 1/8". I'd just run it continuously and pre-shrink it on the wire, then glue it in place with aquarium cement. The latter is clear, smooths out to a gloss print-less finish, and is easy to use (it's basically a clear silicone caulk with high adhesion).