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As someone who has never had a bike with internal brake cable routing (in this case through the top tube), I bought an '87 Panasonic DX 3500 bike for restoration.

The frame as well as many of the components are made by Tange, a Japanese manufacturer.

Before removing rust and touching-up the paint, I am going to strip the frame entirely and that would include the black plastic guides the brake cable enters and exits the top tube through. (BB and headset need replacement, so I would have stripped the frame nonetheless.)

The outer cable is routed through said guides; pulling it on each side makes it move on the other side as well, which means and the guides are attached on the top tube like shown on the photo below:

The rear brake cable guide in question

Having broken hard-to-replace plastic components before, I really don't want to use any force before being sure that's the only way to do this.

I would expect there to be a release pin on the cable guides, but I haven't found any.

Does anyone have an idea about how to remove the cable guides — and in case of emergency, knows how to find a new replacement or if they are non-removable, even for maintenance?

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    You need to figure out how the cable outer is run. Some bikes will use a single long outer all the way to the brake. Other bikes will have a cable stop so the outer finishes, and only the inner passes through the frame. So, when you push/pull the outer at one end, does the outer at the other end move too? – Criggie Dec 28 '16 at 19:45
  • Pulling the one in the back does not move the one on the front side. I will update the post to reflect that. Thanks for the comment. – aldavigdis Dec 28 '16 at 22:57
  • OK - loosen the inner cable at the wheel, and see if the outers will then pull out of the frame. I suspect there's either bare inner-wire through the frame, or possibly a guide tube. Your Outers will stop just inside the mount. – Criggie Dec 29 '16 at 1:24
  • Oops! Pulling the outer cable harder than I dared before revealed that the outer cable is actually routed internally as well. Post has been edited again. :) – aldavigdis Dec 29 '16 at 1:51
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This is going to be hard work given you want a bare frame.

If it were a simple swap of cables, you'd feed the new outer onto the old inner, and pull that up. The new outer would follow the end of the old outer, and it would find the top exit hole because its on the old inner wire.

Once the new outer is in place, you whip out the old inner, and then feed the new inner through the new outer and connect like normal.

You basically don't know if the outer that passes through the frame is encased in a guide tube of some description, or if its just bare in there.

The only way to try this would be to hold the outer at one exit point and try and shove more outer in at the other exit point.

  • If there's a constraining tube it will be impossible to push any more outer into the tube.

  • If there's NO guide tube in there, you should be able to push several centimetres of additional outer into the tube where it collects in a mild corkscrew shape.

Finally - it might be a good excuse to go buy one of those endoscope cameras... I've wanted one of them for a long time but never had a justification. You could whip out the headset and look along the tube to see what you see.

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