Technical > Lighting and Electronics
Taillight Wire Inside Rear Fender (Mudguard). Thoughts?
mickeg:
On my Titanium bike that I built this past spring, I am planning to install a fender (mudguard) mounted taillight and wire that to my dynohub powered headlamp. That bike is primarily used on pavement (tarmac) with occasional use on well maintained gravel trails.
Plan is to run wiring from the headlamp, down the downtube along the rear brake cable to the bottom bracket, install quick connects there (in case I want to disconnect the wire at that point later), then install the wire on the inside (tire side) of the plastic fender to the taillight. Taillight is a Spanninga Pixeo Xs. The wire will be a two conductor wire. The plastic fenders do not have metal strips in them. I do not anticipate using that bike in muddy conditions.
In my research on this forum and elsewhere on the internet, I am finding a variety of ways to install the wire on the inside of plastic fenders. Some people apply tape to hold the wire in place, some people use a hot glue gun, some have used SeamGrip, and some have used Silicone caulk to attach the wire to the fender. I am inclined to use Silicone caulk.
Some have put the wire in the center of the fender, some have run the wire to the side of the fender thinking that road debris will be less likely to damage the wire at the side. I will decide later which I think would work best once I have the bike upside down fender cleaned, etc.
This is the best reference I found on this forum.
http://thorncyclesforum.co.uk/index.php?topic=12185.msg89179
If anyone has installed a wire inside a fender and had several trouble free years of taillight operation, I would love to hear how you did it.
And if anyone tried the Silicone caulk method and had a failure, I would very much like to hear what happened? And if that happened, do you have any suggestions for doing it better?
I am only thinking of doing this on my Ti bike. I plan to continue only using battery powered taillights on my Nomad and Sherpa.
Thanks in advance for any suggestions you have.
Pavel:
the shop did it that way with my moulton. They used epoxy, and seeing that it's tougher than the fender itself I didn't mind it, but though out of sight it ruffled my sensibilities that neither the wire nor the application of epoxy was straight and smooth enough. Next time I'd use 1" or so Gorilla tape and then use a spatula to make it permanent with a thin layer of epoxy. I have no idea how it would turn out.
one point I'd like to mention is that two quick releases may be in order. On so that the fender can be taken off, and one just before the light so that the rear light can be taken off in the case of damage to either the fender or the light. The moulton was epoxied right to the very end and I can't remove the light from the now useless fender because even the mounting screws are epoxied, and there would only be 1 cm of wire left exposed from the light - too little to make further use of it. On my thorn I decided instead to run my wire into a length of aquarium tubing to protect it and tied that on to the underside of the rear rack instead. I like that better all in all as it's more versatile and a lot less work to install.
mickeg:
I would not glue my light to the fender. I have not received it yet, only ordered it today.
https://www.ebay.com/itm/Spanninga-Pixeo-dynamo-dynohub-tail-lamp-The-most-versatile-we-have-tested/273028783027
The photos suggest that there are two 2.8mm spade connectors that I plug the wires into on the light. It looks like it has a block that holds the wires onto those spade connectors but I might instead be able to use the standard spade connectors. I would decide later which connectors to use.
I agree that if this light or the wiring does not work out, I want to be able to remove the light from the fender and continue to use the fender.
I better check my inventory of 2.8mm spade connectors, I might be running low.
Danneaux:
--- Quote ---If anyone has installed a wire inside a fender and had several trouble free years of taillight operation, I would love to hear how you did it.
--- End quote ---
I've successfully used several methods as described in that Forum link you provided, George. All have been reliable for 30+ years, 20+ years, and more recently (Nomad) 5.5 years. The routing alongside the inner fender lip secured with beta-cyanacrylate (super super glue...the kind that will also glue rubber, wood, and leather) gel proved the most durable for me. The routings down the center of the fender with the foil tape were still working but ultimately removed by me due to a tatty appearance due to impact by mud and debris. The foil was a mismash to peel off, loose in laces where it had been pierced, tightly adhered elsewhere.
--- Quote ---And if anyone tried the Silicone caulk method and had a failure, I would very much like to hear what happened?
--- End quote ---
I had both an initial and eventual failure of silicone caulk.
--- Quote ---And if that happened, do you have any suggestions for doing it better?
--- End quote ---
When new(ish), plastic fenders are both slick-surfaced and may have mold-release compound on them. It is best to remove both or silicone caulk will not adhere to the fender properly and will pull loose (my initial failure). Cleaning the fender with 99% isopropyl alcohol, lightly sanding the track where one intends to route the wire and reapplying the alcohol made for a secure bond for a long time...but (except for ShoeGoo), the silicone caulk was one of the few methods I used that also failed after some years. It simply began to peel at the edges and then pulled free. For that reason, I did not use it again and re-settled on the beta-cyanoacrylate gel which has been most reliable for me in my use (yours may not be the same). I secured the wire with spring-loaded wooden clothespins and waxed paper between the pins and the wire to prevent sticking -- and doing a roughly 5cm section at a time. The gel dries within several minutes, so it is not a great burden to march the clothespins along a section at a time. Of course, it helps to first straighten the wire so it is as flat as possible.
In my experience, plain 2-part or quick epoxy has poor peel strength on flexible fenders over time. I've had better luck with an etching polyamine-polyamide epoxy like JB Weld (the non-quick kind) after the sanding/99% isopropyl application, but still found it less ideal than the beta-cyanoacrylate gel on plastic fenders over time and hard use. It can be incompatible with some wire insulation formulations, causing it to become permanently sticky.
As with Pavel, I would prefer two connectors at the rear fender...one between the fender and bottom bracket so the fender can be readily replaced and a second connector at the taillight so it can be replaced in the event of failure or a desired upgrade.
All good luck, George.
Best,
Dan.
mickeg:
I do not understand your ShoeGoo reference, are you saying that would be better or worse than Silicone caulk?
I initially thought of trying Shoo Goo, but in my internet research I found a few people using Silicone caulk but nobody suggested Shoe Goo.
The super super glue gel you cited does scare me a bit, I am less than enthusiastic about that as I would rather not glue my fingers to anything.
Sandpaper, what grit do you think would work best? I was thinking something pretty fine like 400.
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