Sanyo Dynohub Install, pt2, tailight!

Busch and Muller Securlite

After the initial installation of the Sanyo dynohub and Lumotech headlight, I began planning the addition of  a dynamo driven taillight. Because, well just because.

I ordered the Securlite tailight and an extra 185 cm of wiring from Longleaf, and I was pretty amzed at how fast I got the stuff in the mail. It was like 4 days. I had ordered an extra 185 cm of wire with the taillight, when I opened the box, I found that the light comes with 210 cm of wire. I thought I probably didn't need  the extra length. But as things turned out, it was a good thing that I did.

I spent a long time thinking and planning how I was going to run the wire. I first thought about having the wire follow the rear brake cable stops along the top tube, then snake it down a seat stay to the rear brake bridge and the under the fender to the taillight. I finally decided against this for two reasons: One, the wire would be exposed at the top tube, probably easily snagged and it was not a very clean look. Also, running wire down the stay would not look great either.

I decided to run the wire inside the down tube, by drilling one hole up near the head tube, and another in the bottom bracket. That's not as crazy as it sounds, since I've had several bike which had opening in the BB shell.

Slightly fuzzy picture of the first hole in the upper down tube.

Gee, drilling through the down tube was easy! A little unnerving I guess. I had to enlarge and refine this hole to a slightly oval shape. Drilling a hole in the BB was a little trickier, but it worked out okay. It happens that the BB I'm using, (a Shimano UN72) will allow plenty of room for the wires to fit inside the BB shell. I've heard reports that other BB's don't allow that much room so be warned if you try this at home. You might want to put the exit hole in the bottom down tube rather than the BB shell.

Another fuzzy shot, but you can see the hole in the BB shell.

After having these two holes prepared, I then had to fish the wire through the down tube. It was tricky to do, not as tricky as the fork blades, but I still had to work at it to make it through. I then brought the wire through tp the chainstays and began planning my next wire run. At this point it was obvious that the supplied 215 cm of wire was not going to make the run I wanted. It was a good thing I ordered that extra wire!

I decided to run the wire from the BB to the bottom of the rear fender, then along the inside of the fender to the light. It was probably the cleanest path I could come up with. I wanted as little wire showing as possible.

Here's a shot of the spliced section of wire.

Wire running up the inside of the rear fender, eventually to the taillight.

I fixed the wire to the inside of the fender using metal tape I had left over from a storage shed assembly. This stuff is amazing. It sticks well and is very strong. I have a lot of confidence in this installation...even though it looks like crap! It's inside the fender, so nobody will ever know.

Completed installation. I've wrapped the wire with electrical tape to protect it from the edges of the hole.

Rear view of completed installation.

So that was the installation. I was pretty satisfied with the overall look, with very little wire exposed. Actually getting the light to work was a bit of a challenge for me. At first it ran all the time the front wheel turned! I had wired it so it apparently bypassed the on/off switch. I tried several wiring schemes, even emailed Anthony at Longleaf about it. He had not heard of the problem before. Well, I pulled all the wires from the headlight and re-installed them and this time they worked! the proper combination ended up being this:

(Looking at the back of the headlight, left to right): taillight lead, black/white left terminal, then solid black taillight lead  on the right terminal, Dynamo lead, black/white left terminal, solid black on the  right terminal. 

This ended up giving me the proper ability to switch both head light and taillight with the switch on the head light!