Bicycle Mechanics - seized cable housing in TT; best solution?
Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.
02-09-12, 08:30 AM
I have a steel framed bicycle with internal routing of the rear brake cable. It goes into the top tube behind the head tube junction, then emerges near the seat post junction. It has the little eyelets in the TT where it goes in/emerges that are part of the frame. (sorry don't know the proper word for them.)
The brake cable housing runs into the TT and continues for the entire length, coming out the rear eyelet and continuing down to the brake.
The problem is that the housing has split where it enters/emerges and the inner wire coiling has seized to the frame. No amount of pulling/pushing, WD-40 soaking, etc. has dislodged the cable or corrosion.
I'm wondering what is the best method of getting the housing un-stuck?
I thought about carefully drilling it out, after removing the cable, but I need to free up both ends. If I drill at both sides, it seems like the piece of housing inside the TT would then be pushed in and drop inside the TT. This doesn't seem like a good thing, but maybe I could remove the fork or seat post and fish the piece out?
I'm hoping someone else has run into a similar (frustrating!) issue and can provide some expert advice.
And, of course, once this is out I'll have to figure out how to thread in the new housing without anything inside to guide it, but that seems much easier than this removal challenge. (I do think folks have used vacuums to get the new housing in. Or, if I do end up pulling the post/fork maybe I could just guide it in that way. I'm not positive though, having not pulled the fork/post yet if I have clear access to the TT)
02-09-12, 09:49 AM
Internal cabling is handled a couple ways- The best way is to insert a full-length steel tube, inside the TT, to encase the cable housing. This makes it much easier to pull in new housing. The other way is to just insert short pieces of tubing in the drilled holes. This method makes it very difficult to re-cable. Both would be brazed into the top tube.
My guess is that your cable isn't actually siezed in the "cable guide" from corrosion, but could be if the bike is really subjected to moisture. I'd think though that the cover on the housing is swelled, or has caught on the edge of the guide tube(s).
You don't have enough access through the headtube or the seattube to do you much good. Just grab the cable with some vise grips and pull like crazy. It'll either come out, or unravel and come out that way. Or, not come out at all, in which case you just route the cable externally.
02-09-12, 11:05 AM
Try pulling on the cable housing from both ends simultaneously. If the coating is cracked and the wire spiral distorted, that may straighten out the whole mess.
From your description I suspect that the frame has a tube brazed within the top tube, through which the housing is threaded. Water can wick into the gap between the housing and tube causing rust and binding it together. Usually I can free these by threading an inner wire then pulling hard, alternating direction until I get some movement.
But if it's really stuck, I'd use some penetrating oil first, not WD-40 but something like Liquid Wrench or Kroil. Besides oil these have chemistry designed to attack the rust itself and so should provide some relief.
If that fails I'd try warming it with a hot air gun - one made for removing paint, a hair dryer isn't hot enough. Being careful not to damage the frames paint I'd warm the tube as hot as safely possible which should soften the housings plastic outer cover.
Last resort would be to carefully use pliers to grab the end of the housing's steel coil and pull it hard enough to hyper-extend it which will reduce the diameter and lett you pull it out as a stretched wire. Be careful not to snap it. Once the wire is out then I'd use a length of bare housing chucked in a power drill as a plumber's snake to clean out the plastic.
Once you get this cleared, use plenty of stiff grease or silicone lube on the next cable to prevent a repeat.
I betcha it's the plastic coating over the spiral wire that is getting the cable casing stuck. It must have split and bundled up like a sock at one end jamming the casing in place. That will be a hard thing to fix as everything you need to get at is inside the TT. All I can think of is using as much pullingforce as you can on the spiral wire without damaging the TT and the holes where the cable comes out if. Porblem might be is if you do pull it out, some junk might get left behind in the TT if there is no continuous tube in there to gude the cable casing.
Internally routed brake cables were sort of the rage back in the mid 80's but it seems like it wasn't always such a good idea as what happened on your bike. That's why it's always good to check on the condition of the internally routed cables everytime you consder buying a used bike.
02-09-12, 12:37 PM
if you are lucky your frame may provide access to the top tube (and hence a solution) via the seat tube and/or head tube. (some DISassembly required!) it's a longshot, but probably worth a try. i have a bike with the same rear brake cable set up and eventually i had to unravel the coiled metal part of the housing from the outer plastic part. leaving the plastic part of it occasionally rattling around in the top tube for a couple of years.
eventually, after disassembling it for a repaint, one end of the plastic housing peeked it's head out of the top tube and into the head tube and i GRABBED IT! yeah! :thumb:
i think traditional steel frames mitered the top tube at both ends and then brazed it to the top and seat tubes. but the builder may have drilled (like mine did) a relief hole to facilitate brazing for some reason...
02-10-12, 06:26 AM
Thanks for all the feedback!
I'm working with the LBS and they seem on top of it. One end is now moving and we're going to try a small Dremel bit to dislodge the other end. This might chip a bit of the paint around the eyelet part, but only just a bit. Thanks as well Chombi and Huey.
He was able to get the FD/RD recabled, even though they are also internally routed. Used a magnet, which I thought was crazy talk, until he pulled it off.
Not positive if it has a tube inside the TT, but we'll see today. Also, he needed to pull the seat post, which I try to never pull because it has an internal collar, which would not be easy to fix if overtorqued. He said it was spotless and corrosion free. I have pulled and cleaned that before, but not often. Never recabled it and the bike came used from NYC. I'm guessing the previous owner rode it in all conditions and was not very good about recabling or even pulling the cable and lubing the outside. Oh well, my fault for not breaking it down sooner.
Hope we get this solved today! I love to ride this particular bicycle of mine and it's been in pieces for weeks! Ah, the ago of seeing it hang on the wall in my house in pieces...
I'll go in today and check it out with these suggestions in mind. I like the double pull, HillRider, I also like the the Liquid Wrench solution FBinNY.
02-10-12, 06:35 AM
And thanks as well Chombi and Huey for the advice! It's appreciated!
02-10-12, 06:55 AM
And Chombi...I was still a bit green in my learning curve when I bought this bicycle. Kicking the tires, ya know? Never would have thought to have check the cables! Even worse...it has a compact, which never feels right. I didn't even realize the compact/standard difference back then. Ugh, what an embarrassment! All I can say is that I've come a long way since then but, of course, still learning, as this thread shows:thumb:
I think the previous owner must have ridden in rain & through winter salt/grime and not recabled often enough. Not a good idea on a bike with internal routing, nor such a nice bike!
Powered by vBulletin® Version 4.1.12 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.