How do you thread brake cable through top tube?
 

Just picked up a 80s Gitane as my next project, and it has the rear brake cable threaded through the top tube. I have left it in for now, but plan to replace the brake hoods, so will need to remove the cable, or at least clip the cable head off, to get the new hoods on. And so will need to replace the cable.

What is the best way to do this? When I see frame with this type of cable routing for sale, they usually have the cable left in place. I can picture attaching a new cable to the old (perhaps with some heat shrink tubing, or with epoxy) and pulling it through. But I can also picture that separating half way through and causing a headache.

Some of you must have dealt with this before so thought I'd ask. Thank you!
https://cimg2.ibsrv.net/gimg/bikefor...2039d0e438.jpg

I assume you mean putting new cable including housing in, correct? (if just the inner you should be able to easily push a new inner through the housing).

On my only bike with this set up I tied a string to the cut end of the old housing and pulled it through, tied a washer to each end to prevent loss. Tied the string to the new housing when ready and pulled it through. Its not a huge drag, and this worked fine but I did eventually figure out you can pretty easily fish a stiff wire through (if you are patient)

Pull off brake lever and cable, leaving the existing housing in place. Replace new cable into existing housing. Remove old housing keeping cable routed in place through top tube. Thread new cut to length housing onto cable through top tube. In other words, don't fully remove that which may have been fished through unless you have to.

If there’s nothing in place, try feeding a thread through one end with a vacuum attached to the other opening. Once the thread emerges, tape a cable to it and pull that through. Then run housing over the cable.

On my wife’s former Erickson, I was super careful to always leave something in place, and ultimately it was a cable entry that contributed to that frame’s demise.

I've owned 5 (still have 4) Italian frames with cable routing through he top tube. All had an internal tube (conduit) that the cable ran through. One was designed so the outer housing was also routed through the top tube .With all the others just the inner cable ran through. All I needed to do was feed the cables through one end and out the other. This doesn't mean yours is the same. I never trusted French bikes.

I always thought holes in the tops of tubes that you didn't want water to get into were a bad idea.

Okay, it looks like this is designed with an internal conduit. The outer housing ends at the entrance to the tube. For a test, I tried running another brake cable in alongside the existing brake cable, but it didn't fit. A derailleur cable DID fit, and on three tries, it always popped out the other end. So it looks like there is an internal tube running all the way through. Phew..... Thanks!

https://cimg8.ibsrv.net/gimg/bikefor...6bef0c35b9.jpg

I know I say this for everything -- but doesn't Park Tool make a tool for this? :p

Oh, wait, photo in post #1 says "made in France". So I presume a different size and the tool does not fit.

One suggestion. Put a little grease on the cable where it goes through the tope tube. I've run them dry and they rattle a little. The sound is annoying.

And speaking of things where you don´t want water. That seatpost. I´ve not experienced it myself, but others have reported problems, when using fluted seatposts, where the fluting extends into the seattube. It´s an ideal water trap, and it can supposedly lead to stuck seatposts.

I'm glad I read about strings and vacuums on here. I recently had to thread some wires through my lathe. Couldn't get it to work by just feeding it through, there is a sharp bend.

You're not entirely wrong. But it often doesn't get much worse than some flyrust on the inside.

http://i.imgur.com/zw2KYZx.jpg
​​​​​​​http://i.imgur.com/dLW1WzQ.jpg

Bung a cork in the top of any hollow ones.

And yes, seatpost flutes are a Completely Stupid Idea.

I won't argue that but they do dress a vintage bike up a bit. When I put the white lithium grease on my fluted seat posts I always make sure there is enough in the flutes to seal them at the top of the seat tube. Wipe the excess off flush to the seat tube using a Q-tip in the flutes and no moisture can get down the flutes.

A little clear nail polish applied around the cable housing at the openings for through the frame cables would help seal them against moisture. I also plug any unused threaded frame holes with stainless steel set screws and then seal them with clear nail polish to keep them from backing out and to keep moisture from seeping in around the threads. Probably overkill but it makes me feel better LOL.

Ditto, the thread trick. There are several other tutorials on YouTube for fishing cable and/or housing through internal routing.

When I got a 2014 Diamondback Podium frame with internal cable routing -- minus the original cables -- I procrastinated for months before building up that bike, thinking the cable routing would be a nightmare. I finally watched some Diamondback industry promo videos for that bike. Turns out it was pre-fitted with internal cables. I'm not sure whether it's standard metal sheath or just cable liners. But as long as the original internal housing is in good shape, all I need to do is thread through the new cables. Easy.

If I ever do need to replace the inner cable housing/liners, I'll use the trick of attaching the new cable liner/housing to the old and use that to pull it through.

Ditto, the rattling thing too. Mine rattles a bit on chipseal, between the top tube and head tube. Not enough to worry about. But I can tell the inner cable liner/housing is tapping against the fat, hollow carbon fiber tubes. I might eventually get a fiber optic camera doodad and peek inside to see how it's set up and whether they used those rubber bumper ring doodads.

To thread new housing through the top tube:

I insert the cable into the housing and leave an inch of cable sticking out of the end and bend it at an angle. Insert it through the front hole, push the housing through the top tube and when the tip of the cable approaches the rear hole I twist the cable on the other end. That helps the bent tip find the hole and then I grab the tip when it pops out and pull the entire housing out of the rear hole.

Earlier this week I had to re-cable a Burley tandem. Both shift cables routed to DT penetrations near the HT then open air to the rear, thru the DT, the front BB shell, the cross tube to the rear BB shell then out the tube opening. UGH, about 4ft of tubing and two shells with no internal housing or conduit or nuttin. "Ah, I read about this on BF C&V"

I got out the long length of tubing that Jagwire sells, just like shift cable liner, translucent, stiff and just big enough to cover a brake cable. Cut the first cable about a foot from the rear tube opening then CAREFULLY fed the tubing over the cable, past the two BB shells , up the DT and, with some fiddling, trial and error out the penetrations at the front. Pulled the old cable out and fed the new cable in. Pulled the tubing and repeated for the second cable. Slow and deliberate but that worked fine. I needed a coffee break after that.

BTW, I've had NO luck attaching a new cable to the old and pulling it through. Tape does not work on old oily, dirty cables let alone the new cables. Whatever you use to connect the two cables, if it does hold, gets snagged somewhere inside the frame.

@Prowler - I have a Duet and left the cables exposed. Do you have pics?

My Pinarello presented a challenge. The housing cover would not fit in the entry on either end. I stripped the cover off and inserted the inner housing, which ran into a stop.
https://live.staticflickr.com/8117/2...504e70d8_b.jpgP1040364 on Flickr

final install:
https://live.staticflickr.com/2910/1...6d89261b_b.jpgP1020203 on Flickr

Sorry, no pix. It was a customer's bike and he's pick it up. His DT penetrations were large enough to accept std steel 4mm cable ends so I did not need an alternate solution.

When I ran a new shift cable through the chainstay on a Trek, turning the frame vertical in the work stand helped a lot.

https://cimg0.ibsrv.net/gimg/bikefor...0b3cf07ff1.png
Cut a length of this and run it over the cable while its in the frame. Hold the liner in place and pull the brake cable out. Run the new cable through the tube. Pull the black tube off the cable and save it for next time.

Had the same problem with my Montello.. I think Pinarello meant to just run the cable bare within the top tube as all the Montellos I have seen have reducing ferrules at the top tube cable openings. It does work that way ok, but it always bothered me that the cable is in there sawing at the top tube steel when the rear brake is operated. I just greased the section of cable really good where it is in the top tube and left it at that, but maybe next time, I change cables on the bike, I'll try to run cable liner in the top tube.

@Chombi1 - Do you have a pic? I haven't looked for nor have I seen a ferrule approach.

This right here is where my trust issues with steel frames come from lol 😅.

On a side note, internal guide tubes (ones I've seen anyway) are usually brass tubes, not steel, brazed to the top tube, so there's really no potential for rust damage, it is the worst place for constant water ingress as the tubing is at its thinnest.

Oh absolutely, though chances are this particular bike was left outside in the rain for longer periods of time. I had a hell of a time to remove the rusted sealed bottom bracket and well.. this is how I bought it:

http://i.imgur.com/6biH1B0.jpg