How the heck do your get cables through the frame?
 

My son and I are trying to build up a 1985 Trek frame, which routes the rear RD cable under the BB and through the chain stay, to come out by the RD. We have been driving ourselves crazy trying to get the cable to hit the tiny hole. Any tips on how to get this cable through? I always thought the idea of frame routed cabling was neat, until now. Thanks.

An idea from running electrical cable through conduit. Use the old cable to pull it through if it wasn't already removed. Since by your post it sounds like it was already removed, you might try putting a cable through backwards. It might be easier to hit the the hole by the bottom bracket. Then use that cable to pull the new one through in the correct direction. I know they have tools/snakes for that purpose in runing cable through conduit. Perhaps there is something similar to do the same through the chain stay.

Another idea I just had. see if you could drop a string down through the chain stay and the try to snare it with a hook at the hole by the RD. Kind of like the little wire things used to thread a needle. Then use the string to pull the cable through.

You could use string from a weedeater, run it though the frame and when done run the cable 's housing thou. some use a vacuum cleaner to pull the housing or string .

I remember one fellow taught me to use a spoke to try to snag the housing from the other side

It's a fight but it can be done. I had an '87 Trek 560 frame with the same absurd cable routing. You do know that only the inner wire goes through the chainstay, not the housing, right? I know that seems like a silly question but I've heard of some owners trying to get the housing in there too

Be sure the end of the wire is absolutely smooth and free of loose strands and just keep wiggling it around while pushing up and back from the front. It wiil pop out eventually.

If you get too frustrated, you could fit a clamp-on cable guide to the chainstay and route the housing and cable under the chainstay like civilized frame do. :)

Yeah, I am only trying to get the actual cable through, not the housing. I'll try some of these various ideas. Thanks. If I come up with some really clever trick, I'll let you know. If not I'll post pictures of the frame beaten to hell with a hammer, which is how I am starting to feel about it.

I've read you might be able to use magnet to guide the cable through an aluminum frame. I've also read that some people put a thread in one hole and use a vacuum cleaner to suck the thread through the other, then tie the end of the cable to the thread and pull it through. Either way, put some super glue on the end of the cable to keep it from unraveling.

I have an old Klein that uses the same routing. When it was new and I first built up the frame. I was able to wiggle the cable through the hole somehow, but as I recall if involved lots of beer.

The magnet works the best or the cable in backwards and tape on the new cable to it.

While a lot of these tips work great on most frames, Treks of this era are absolutely incorrigible in their difficulty. I struggled and struggled, and then gave up and took it to a shop; little did they know that it was a mistake to charge a flat fee for cable replacement.

I've actually gotten so fed up with it that I took a drill to my bike (the only time I will confess to doing something so rash). You can actually expand the hole that the cable leaves quite a bit and still have it function as a cable stop.

Those Trek frames were steel so the magnet trick doesn't work. The trick isn't getting the cable through the chainstay, it's getting the end of the cable to find the small exit hole.

Gotta ask...

Why not just run the cables along the outside of the frame like most bikes?

Try twirling the cable back and forth between your fingers. I have an old SR Litage frame, was ready to throw it across the room when I accidentally hit upon this trick. It may be frame specific but I think some frame have guides inside the tube to help. Or I'm just lucky, but I did pull them out and feed them back in several times.

Make sure the cable end is cleanly cut. Solder it if possible, and file to a point. This will help prevent it from getting snagged.

Trek installed a small plastic funnel inside the chainstay to guide the cable through the exit hole. Although it may have fallen out, I find it unlikely because it took a pretty good tug to get them seated in the first place. Has the frame perhaps been powder coated since it was new? The heat of powder coating may be sufficient to melt the plastic funnel.

I must have been so lucky. I built up an '86 660 last month and got the cable through on the first try. I assumed it had an inner guide or something because it was so easy. I guess I should have bought a lottery ticket that day.

Yep, we had the frame powder coated, so baked that plastic funnel I'm sure. Tried several of the methods and finally took a drill to it and enlarged the hole slightly. That did it. Thanks for the suggestions.

I don't know why they make frames like this. They must be sadists.

No one mentioned this method, so here's something else to try. You'll need a length of thin plastic tubing, like electrical spaghetti available from radio Shack.

Push a wire down starting from the chainstay, to the BB until it sticks out both ends. If you can't get a wire threaded, a heavy needle pulling thread might work by turning the chainstay vertical and using gravity.

Thread the spaghetti over the wire until it too sticks out both ends. Now remove you're guide wire and thread the gear wire through the tube until it's through and finsih by sliding the tube out.

You might (that's might, but not necessarily) have to enlarge the chainstay hole a hair to clear the tubing, but don't exceed 2.5mm. A decent ferrule will hold against the enlarged hole without any problem.

Put the frame in a vise so that the chain stay is perpendicular to the floor, then gently stab the cable toard the hole. This worked on my Trek Cirrus 520 after only a few tries. Somehow, putting the chain stay in a vertical position makes it easier. I did not know about the plastic funnel as described by JDThompson---that makes the internal routing design seem less crazy.

You'd have to ask the Marketing Department. It was their idea.

Yeah, it's always a good idea to the people who don't have to work with it themselves.

I also never understood why they ran the rear brake cable inside the top tube of their bonded Al frames like my 1420. There was no internal guide tube so rethreading it was a dreadful nuisance the first time after you completely removed the old cable and housing and before you realized what you had done. Also, the unguided cable had a very annoying tendency to rattle in there. Bad idea all around.

I wouldn't mind internal cables without guides; string and a vacuum cleaner the first time, and from then on just use string when changing cables.

IMO the aesthetics are worth the minor hassle.

Can't see the point of only doing the chainstay that way though...

I picked up my 400 frame from the powdercoater yesterday. Can't wait to run that cable!
I never had any trouble running the housing through my AL frame one but knew enough not to pull it out without thinking.

The cable slipped right in the very first time! Went to get a tool (didn't expect it to be so easy) and it came out while I walked away, but went right back in the second time.