Electronics, Lighting, & Gadgets - Wiring a rear, fender-mounted, tail light

I am just a few small parts away from finally having a battery-free lighting set-up, but I'm wondering about the tail light.

My tail light mounts to the fender. The wires, I assume, will have to run along the inside of the fenders, which sounds like a good place for them, but how do I make the wires stay on the fender rather than rubbing the tire? Is there a tape that will hold when faced with all the rain, snow, and mud that's likely to find its way under the fender? Can anyone recommend a solution for this?

It might be easier to run the wire along the fender stays and then duck behind the fender to the back of the light.

I've used hot melt glue on my Planet Bike black plastic fenders with limited success.
I plan on redoing the wiring this fall with silicon sealant.
Good luck!

If they are metal fenders (aluminum or stainless) drill a hole so the wires can run inside the channel created by the edge fold.

If they are plastic fenders then maybe some plastic channel glued to the fender with plastic epoxy or plastic weld, to run the wires in.

They're aluminum fenders, so maybe the wires can run in that fold. It looks like a tight fit, but maybe it could work. Failing that, I like the idea of gluing a channel rather than the actual wires because re-wiring would be easier. But just for simplicity's sake, I'm wondering if there's some kind of all-weather tape that would adhere to the aluminum and not loosen when it got wet. I guess that might be a bit much to ask.

So went to Lowes and typed "all-weather tape" into the search box and was shown a roll of duct tape. Since duct tape will fix absolutely everything, I don't know why I didn't think of that to start with, but I wonder if it will really keep its hold on aluminum through water and changing temperatures.

So went to Lowes and typed "all-weather tape" into the search box and was shown a roll of duct tape. Since duct tape will fix absolutely everything, I don't know why I didn't think of that to start with, but I wonder if it will really keep its hold on aluminum through water and changing temperatures.

A lot of different brands of duct tape with different adhesive characteristics so if Lowes info listed a brand then I would check the manufacturers web site to see if they list specifications for the tape that Lowes listed.

Good thought. Lowes served up 3M Heavy Duty All-Weather Duct Tape. The 3M site says:

A heavy-duty duct tape for extreme conditions. Resists drying, cracking and peeling caused by the damaging effects of sunlight, heat, cold and moisture. Lasts three times longer than other gray heavy-duty duct tapes.
Recommended applications


Indoor and outdoor repairs
Heavy-duty patching
Masking rough surfaces
Long-lasting repairs

It sounds like it might be worth a shot if I find that can't route a wire through the folds on the edges of the fenders.

If you're going to use tape, use Gorilla Tape.
I put a piece on my bike to cover the hole where I lost a water bottle holder screw. Left it on all summer (rain days included) and it was a [female dog] to get off. Tuff Stuff

Popular Mechanics thinks so too.
http://www.popularmechanics.com/home_journal/how_to/4306415.html

Ooo, thanks for that. I might make Gorilla Tape my backup backup plan. If All-Weather Duct tape will do the trick, and will be possible to remove later if I need to, that might be the way to go. If Gorilla Tape is that sticky, it might be better to use it to tape some kind of tubing or channel to route the wires through rather than taping the wires themselves.

I was happy to find this thread since I came here to post the exact same question.

Also wondering if any of you have drilled holes in your down tube to route wiring internally? Seems like a small hole near the head tube and another just above the bottom bracket wouldn't do too much to compromise frame strength. Seal them with silicone caulk after the wire is in to keep it in place. I'm talking about a steel frame (Surly Cross Check). Is this a crazy thing to consider?

I have considered doing that on a mixte bike I have where you could route the cables all the way to the other side of the head tube without interfering with the working of the head tube. I haven't and probably wouldn't consider it with my trucker. There would still have be wires routed around the head tube, and to me that wouldn't look any better than routing the wires outside of the frame, but that's just me.

I'm not sure if it still exists but some automotive dept. were selling a type of metallic (alu) tape to repair pierced car mufflers. That tape was strong and long lasting and would certainly do the job..

I like the idea of the channel the best, but if you wanted to hold the wires with a bead of glue, I'd suggest looking into Marine GOOP. I've got wires held in place along the top of my truck canopy with dobs of this stuff, and it holds air in my inflatable boat. It's good stuff.

I have Honjo fenders and ran a single wire through the fender bead and it works fine. Notch the inside of the bead with a file near the tail light to get the wire out and either drill a small hole next to the fender, or simply loop the wire outside the fender. The tail light should be grounded to the fender so you can simply connect the ground wire at the theadlight to the fork to make the return connection and use only one wire.

If you don't want to run the wire inside the fender bead, then use some RTV silicone to tack the wire agaist the fender bead every few inches. Don't use tape. Tape will come loose.

I was happy to find this thread since I came here to post the exact same question.

Also wondering if any of you have drilled holes in your down tube to route wiring internally? Seems like a small hole near the head tube and another just above the bottom bracket wouldn't do too much to compromise frame strength. Seal them with silicone caulk after the wire is in to keep it in place. I'm talking about a steel frame (Surly Cross Check). Is this a crazy thing to consider?

My steel randonneuring bike has holes drilled in the underside of the down tube just behind the head tube and just above the BB shell for the purpose of running a tail light wire. There's a grommet in each hole to keep water out.