Frame Modification Suggestions to Route Dynamo Wiring?
 

I'm having my seven-year-old Cross Check frame stripped down and powder coated. In the process I'm also having some simple modifications done such as removing the derailleur hanger, rear brake bosses and all cable stops -- this bike is only used as a fixed-gear commuter.

I use front and rear dynamo lights for this bike. I don't mind having the wires along my front fork, but for the rear the wires are a bit of a bummer. If there's a simple modification that can be made while the frame is stripped down, I'd love to ask the person who is doing the work to give it a shot.

Any thoughts or suggestions?

I'm currently using a fender-mounted tail light, and I have the wires zip-tied down the down tube, under the bottom bracket, and then run along the inside of my rear fender to the light. (Inside the fender I have the wires held in place with a healthy bead of caulking.)

One idea I have is to see about having a conduit welded along the down tube before the powder coat is applied. Has anyone tried that?

(Yes, I'm aware that economically I'd be better off to sell the frame on eBay and buy something new, but I'm okay with going this route.)

I have considered using hydraulic brake line clips like this one. There are also the wire tie versions like these

Thanks for the suggestions! I met with the guy doing the work yesterday -- the frame has been stripped and the "offending" braze ons removed. It looks pretty sleek.

Anyway, we stared at it for a while and decided to drill a hole into the underside of the down tube near the head tube. I'll snake the wire in there, and I'll pass it into the bottom bracket shell and out the vent hole at the bottom of the shell. We checked, and my bottom bracket will provide enough clearance for the wires.

For the forks, he's going to slightly expand both the vent hole at the top and bottom of the fork blades. It will be tricky, but that will give me enough room to snake the wires inside the fork and still leave a little opening for venting.

Your next challenge is to come up with a solution to stop the wire from making noise while bouncing around inside the frame.

Oh, why do you hurt me so! Seriously though... you raise a very good point. Is this why more people don't do internal routing?

Running the wire through the fork blade and fork crown is the neatest solution but is a plumber's nightmare. Life is too short, IMO, so I braze old fashioned top tube brake cable guides onto the inner side of the fork blade and run the dynamo wires inside those. Then I drill a hole into the lug under the down tube and run the wire from under the fork crown into the hole. I like to use an integrated tail light built into the rear of the seat tube so I run the wire through the down tube, above the bottom bracket spindle, and into the seat tube, but can't think why running it under the spindle and out a hole in the BB shell wouldn't work.

I've never heard any noise from an internally run electrical wire.

those kind of noises are for when you're obsessively trying to hear them while shaking the bike. Riding, you probably are not going to hear anything. I would reinforce the hole in the downtube

Yeah, but I'm like that ;) That said, I think the hole leading into the down tube from the bottom bracket shell is large enough that I could push some bubble wrap in there (or something like that) that would keep the wire off of the tube.

Any suggestions for how to reinforce the down tube? I don't think the hole will be very large -- perhaps 5 mm in diameter. But, then again, the only Cross Check I've ever seen fail crumpled right about where the hole will go.

Rationally I know you're right about life being too short to obsess over things like this. That said, winter is here in full swing, so this is a fun distraction. Perhaps I'll give up once I try the actually fishing with the wire.

Thanks for the suggestion about coming up the seat tube. I suppose I could come all the way up and perhaps even out the seat post above the collar and mount a light there -- is that what you do? Otherwise, I suppose you must exit the seat tube below the lowest extent of the seat post, but then I'm not clear how you mount the light there. I suspect I'm being dense...

In any event, thanks for the suggestions and comments!

I'd suggest against using internal routing. Usually there are design time considerations about tube selection with respect to internal routing. And there is almost always a reinforcement tab brazed in around the hole. Also, the down tube is a pretty highly stressed tube, you'd be better off doing it in the top tube.

More trouble than it's worth in my opinion.

I also went with loop on the fork blade and a hole (3 mm) on the DT lug. I brazed a little elbowed tube in the hole to reinforce it and to help guide the cable (it's still a PAIN to fish it through!)

I agree it would be hard to fish a wire in the fork through new holes. I think the proper way is to braze a tube like for rear brake routing, as you are building the fork.

At the recent San Diego bike show I saw a bike with a tail light integrated into the seat post. He used a milling machine to do it, but told me there was a commercial version available. I never looked into it, but some Google-fu might reveal something.

At any rate, I mount the light to the rear of the seat tube the way the old constructeurs used to do it - with a tube brazed to the seat tube and the light attached to the end of it. The wire runs through the tube.

This is my most recent one:

http://i10.photobucket.com/albums/a1.../taillight.jpg

Wow: that is impressive. Very nice work!