carfart

How do you do this? I haven't been able to find any descriptions yet. The production frames that I've seen online look like they have a cable of some sort installed that you'd use to pull the wiring into and through the tubing. Is something like this put in place after the frame is complete or before it's welded together? In either case what's the best material to use for this?

Andrew R Stewart 

I just read the descriptions on how others do this, there seems to be a few different basic methods.

One is to install a length of tubing that the cable will run through while building the fork/frame. Brass or stainless tubes are the choice for rust control. matching the tube ID with the wire's OD is part of the planning, coaxial wires seem to work better. The tube is silver brazed inside the frame member with inlets and exits positioned just so. This, if done well, allows the wire to be fed through the tube with little problem.

Another method is to just have entry and exit ports in the frame and run the wire without a guide tube. How to do this is the trick. Some use a length of thread or fishing line pulled through the frame/fork by a vacuum at one port. Then tie off/connect with shrink tubing to the wire and pull it back through. Similar techniques are used for internal cable routing on current carbon frames. Sealing at the ports becomes needed otherwise water gets in.

A number of builders have looked at their options and decided that internal routing is not worth it or beyond their comfort zone. Andy.

carfart

I like the idea of feeding it through an internal tube for rust protection. I'm having a frame built, so I'll see if they can do that for me. I just fed some wire through a chainstay with no problems. Feeding it through the downtube and out the bottle boss wasn't very challenging, so not having a cable in place for that purpose doesn't seem like a big deal.

Now I'm wondering about bottom bracket routing. It seems like the easiest way to manage this is to just make sure your bottom bracket leaves enough space for the wire to pass. I suspect that there might be a more elegant way to handle that area.

unterhausen

I'm taking my cues from Shimano Di2 wiring. They sell a special bb guard that holds the wire away from the axle, but all the bb's I have played with recently do this anyway. I recently got a "ultegra di2 wiring grommet" set to play with. They have two kinds, one goes in a slot, the other goes in a 6mm hole. The slot version is shown in the pictures for THIS article.

Everyone I've ever seen describe their process says you can blow dental floss through a tube with compressed air and it will naturally come out the other end. However, I'm planning on using some stainless tubing in some forks I'm building.

tuz

I use short pieces of tubing on the wheel side of the fork blade, a full guide inside the DT, a hole at the BB and then the cable is routed in the rolled edge of the fender. In racks I try to pass the cable (22 AWG) between holes. It's a bit of a pain but once it's there you won't need to touch it for a while. Maybe in the next bike I'll use simple holes in the DT and fork blade as well.

carfart

How do you reinforce your downtube where the guide tube exits? I'm imagining that the guide tube runs fairly straight and is cut at an angle flush with the downtube and that whatever's used to reinforce the hole should have an opening that'll fit a grommet. If both ends of the tube open outside of the frame would you just use internal brake guide coverplates?

tuz

I usually do it on lugged bikes so the lugs acts as a reinforcement. Otherwise I've used a piece of plate or simply let the tube stick out a little and build a fillet. I bend the guide ~45* and the hole is angled as well. No grommets, no brake guide coverplates. Those would work but IMO it would be bulky for a small wire. I use 1/8" thin-wall brass tubing with 1" of 3/16" steel tubing at the ends.

carfart

So this would probably work with the ferrules trimmed down: https://www.cycle-frames.com/bicycle-...-FERRULES.html.

Edit:
Never mind, I found the 1/8" brass and 3/16" steel tubes at Hobbylinc and Hobbymasters.

ksisler

Carfart; Recommend hitting the frame building suppliers list off the thread at the top of this forum. One or two of them feature all the bit to do it in the classic manner and the cost is minor; A long piece of brass tubing and a couple of different types of reinforcements to fit over the ends of the holes. Some provide for terminating a shift or brake cable (with or without a housing stop) and some are more open for wiring like uses. Once you see the bits, it will be really obvious what they do. Here are a couple of leads on the covers...but I don't today see where the complete kits are listed (you may have to check one of the other sites listed).

https://www.cycle-frames.com/bicycle-...OVERPLATE.html
https://www.cycle-frames.com/bicycle-...-TOP-TUBE.html


Edited: Here is a link for the full kits to do internal wiring, cables, etc.

https://www.framebuilding.com/Braze%20ons.htm

Hope that helps
/K

fietsbob

as the wear and tear takes its toll on the wiring insulation consider how you will isolate the
wire where it enters and exits,, rubber grommets are what the auto biz does

you may use electrical heat shrink tubing to do this around the wire as the wire harness is drawn through

stiff wire should push through a well designed internal tube path,

put in the tube before it is built into the frame irself.


BTW the hydraulic brake line in cars is stainless ..

or at least has to be quite corrosion resistant.

I've used it making a canti brake cable guide around the seat tube.

long john

Hey the vacuum and sewing thread has worked great for me many times. I was skeptical at first but tried it and wow it was so easy.

MassiveD

That's how the bats find their way in, air flow.

I would wonder about all the trouble of putting a large piece of tubing in, when there isn't any real need. Maybe one could just run it in and epoxy plug the hole where the wire comes out. There is this perfectly good tube for the wire to run through, so we provide a seperate tube for it to run through? Not really seeing that. Chafe, water, and easier repair are certainly thoughts. Just not convinced it is a reasonable response to that stuff.

OK, so having rejected the crazy, here is another one just for fun. A lot of the problems go away if you get rid of the seatpost, and there can be payoffs for brakes, or maybe gear hubs. The simple method is to have a seat boom. Another option is to have, something else, there are other ways of mounting seats... So back to the boom. I want some seat post, just not so much that it cuts my wires or cable. Main issue I see is getting the thing packed with a honkin boom on it. But that is how the Bike Fridays, roll, so it can be done. And that isn't a problem for everyone, some people bike tour without chugging down a pile of av gas before they get to the starting line.

TiHabanero

Why be so conventional? Bond or braze an ss tube as conduit to the outside of the frame. Think of it as Steampunk. That is what I did on a commuter frame a few years back. I bonded it just to test the idea out and liked it. Thought it looked unique and added some "mechanicalness" to the whole thing.

Make sure you set the angle of tube to drain.