In the early 1980s, I took a different approach when a bicycle I owned sported ESGE Chromoplast fenders. Thinking the foil layer between the clear plastic laminations should conduct electricity, I used a Dremel Moto-Tool and the end of a spiral cutter to carefully remove the top layer of plastic, exposing the foil in spots at either end of the fender. I then drilled a small hole in the crater and passed a stainless steel bolt, flat washer, and nylock nut through the holes, tightening the assembly into a terminal. I then covered the edge interface at the washer with a thin layer of beta-cyanoacrylate gel to make it watertight. Power connections were made with eyelet terminals at either end of the fender using thin stainless flat washers, split washers, and plain nuts, insulated with a small vinyl cap intended to plug an automotive vacuum line. At some later point, ESGE marketed fenders with a snap-lead connection using the same conductive foil idea. The foil inside was thicker and more robust than it appeared. Though still relatively thin, it was wide enough to make a reasonable low-impedance taillight lead.
The taillight I used grounded to the rear rack which was itself grounded to the frame, so all I needed was one power lead. The fender had three separate foil strips, with the fender stays grounded to the center foil strip, so it could have been used in the same way for a ground return. It was a very neat looking setup and extremely reliable.
I commuted with this setup for many years, riding and parking in extremely wet Oregon (USA) weather and never once had a failure using this taillight wiring with a number of generators from that era -- Union 9817, Union BB roller, and Sanyo DynaPower BB roller. The setup was still working when I changed to a wider fender and LED blinky taillight.
As for drilling a frame to route wires internally, I have done it successfully, but only on lugged frames, where the hole was very small and drilled through the center of the underside tang for the headtube-downtube lug and exiting the center-bottom of the BB, generally using a line-bored bolt to replace the one already securing the BB underside derailleur cable guides. It is as simple to continue the lead through the left chainstay to the rack strut mounting. I am a hobbyist framebuilder and have never had problems doing this on my own and commercially-produced frames and no sign of cracks have appeared to date (>35,000 miles of hard touring use on each of the frames). However, on a fillet-brazed or TiG-welded frame, I would have reservations. While the area in question would be butted, without a lug there is a chance for crack propagation away from the drilled hole. I wouldn't try it and I would imagine it voiding a frame warranty. The way to do it "properly" on such frame would be to braze small piece of brass tubing into the hole, much as the Taylor Brothers did on one period frame I've seen. The little piece of tubing extends slightly beyond the hole on either side, serving as a reinforcing lug on, say, a fillet-brazed frame. I've done that successfully on one of my frames, a folder. It is also possible to route wires through existing frame vent holes, leftover from the building process. Some frames already have holes of sufficient size, usually in the stays, and some have to be enlarged or ovalized very slightly. A vacuum cleaner is used to draw sewing threads through the holes and that is tied to a fine piece of florist's wire that in turn is soldered to the end of the electrical lead so it can be fished through. This method can often be used nondestructively on a built frame to route the leads from the BB to the base of the rack strut.
I'm in-process ordering a Sherpa in satin black, and plan to use a combination of zip ties and black automotive trim tape to conceal/route the wire. The trim tape I'll be using is also satin finished, has a very stable low-creep adhesive, and is intended to overlay and replace the finish on black-colored, metal automotive window trim. The brand I'll be using is by Trim-brite; I've had superb luck using it in the past to protect my black powdercoated carriers from pannier hook abrasion.
Hope this helps,
Dan.
Eugene, OR -- USA
