Internal brake routing
 

I recently got a 90s Colnago Master Competition and just put it together. It has internal brake routing for the rear brake and I have a problem. I thought there was a cable stop when it goes internal so I cut the housing to the braze-on on the top tube on both ends. When I put it all together and pulled the brakes, the housing is pulled into the top tube but strips off part of the housing outer plastic. It has pulled in about 3" of housing on the rear and 1" in the front. It doesn't seem to have a cable stop. Does anyone have any insights on how to set it up?

I was thinking about getting housing and strip the plastic outer layer for the section inside the top tube then inserting the housing from both ends. Essentially doing a full housing for the rear brakes. Is this right?

Your Colnago should just take the brake cable, housing and all, through the top tube. In other words, full housing from brake lever to the caliper. On most bikes there is an internal tube for the housing to pass through. Just make sure there are no burrs or anything that would otherwise hang up on the housing.

Thanks for the reply. When I was installing it, I tried that and the housing didn't get past the entrance on either side. That's why I thought there was a cable stop for it. After putting it all together, when I applied the brakes, the opening took a sliver of the outer plastic off. I used a campy housing and also jagwire housing and happened to both of them. Is there a smaller housing to use for this?

If I were you I'd try a little investigative poking around, like with a piece of wire or an old spoke or something. See if you can detect an inner guide tube or not inside the frame tube. Some bikes don't have it, but that should be readily apparent. It still sounds to me like there is a sharp burr causing the damage you're describing. I know that there are different housing diameters for shift cables but as far as I know brake housing is all the same. Don't use a shift housing for a brake cable, BTW.
If there were meant to be cable housing stops on the tube, that should be easy to see. Unless the previous owner did a little "modifying" with a drill.

Did you try using a brake housing ferrule at the holes in the top tube? I don't think this would be the problem but I guess it can't hurt to try.

You don't want to strip the plastic layer off the outside of the brake housing. The spiral housing inside is plain steel and will rust very quickly.

I tried the ferrule and it didn't fit and the housing didn't fit in the top tube so I thought there was a cable stop inside.

Good idea, I'll keep the plastic layer on.

Right now, I had the brakes set up but I rigged it to hold with electrical tape around the housing with zip ties to hold it in place. A temporary solution since I was dying to take it out. I'll take it apart and fish around with an old spoke to see what's happening inside.

I don't know if this photo will be helpful, but my '90's Pinarello has fittings brazed on the top tube and an internal brass sleeve inside the top tube that makes for very easy routing of the brake cable, you simply run full cable housing to the rear brake-

http://i414.photobucket.com/albums/p...d/DSC02032.jpg

The fittings look just like mine but the housing won't fit. Maybe I should use some grease the housing? I think there is a sleeve inside since the cable came right out on the back of the top tube.

BTW, nice Pinarello.

It's possible that you just have burrs inside both inlets to the sleeve. Take a peek inside with a flashlight and if you see any, clean them up with a file.

I'll take a look at this. From all the replies, it's supposed to have full housing all the way through. Must be a burr.

What the on the uber modern crankset on that bike.

You love picking on my Pinarello.

The drivetrain is Centaur ten speed. The bike is a 1997 Vuelta, the stock components were Chorus 9-speed. I don't see the problem. I went with '09 Centaur because it's still available all-aluminum. The bike rides like a dream, and the Centaur group works great. I bought '09 Mavic Ksyrium Elites for it recently (silver) along with black Look Keo Sprint pedals. I'll continue to use the Open Pro/Centaur wheels sometimes as well. I have switched to black tape, cables, and a black Brooks Swift ti saddle. The white stuff was flashy, but it does get dingy very fast.

What??

Come on, that's the first time i've said anything about it :)

Maybe your cable housing is too large of a diameter. Try different housing?

I tried the Campy and Jagwire housing so far. Anyone know of a smaller diameter one? Their websites don't list the diameters.

It may exist but I've never seen brake housing any smaller (or larger for that matter) than 5mm outer diameter.

yeah like the ultra common 4mm derailleur housing...?

So... no burrs or anything in the way? If the housing was meant to end where the cable enters and exits the top tube, (cable housing stops) it should be obvious. Unless somebody altered it at some point. Otherwise then the cable housing should go all the way through the top tube, unless there's a burr or something. I really doubt Colnago would design it so that it required something other than any standard, ordinary cable housing. So it really has to be one thing or the other. You don't need some obscure type of housing. I was hoping a owner of that vintage of Colnago would chime in with some insight. Maybe try posting this in the C&V forum.

I haven't had time to look at the bike this week but will tonight. It's been a busy week. I also have to get new housing first since my other ones were chewed up. It makes no sense to design the cable routing to only accept a non-spec housing cable. I'm hoping for a simple burr and things to go easily.

I posted this in C&V but no replies there. I was hoping the same for some Colnago owners to show me their setup.

I'd bet that the brazed-on fittings and internal sleeve on your Colnago are identical to the ones on my Pinarello pictured above, intended for standard 5mm brake cable housing. The identical fittings and sleeves are still available for custom frame building.

The housing pictured on my bike is Jagwire brand. Perhaps there's a buildup of corrosion in the internal sleeve on your bike?

Sounds like you need a de-burrer on the end of a flex-drill shaft. Don't ask me where to get one of those. :) But i'll bet there's some sort of plumbing tool that would work.

I was thinking the same thing and wondering where to get it... I need something like a steel pipe cleaner that can go on a power drill.

It worked
 

Thanks all for your help. I got it to work tonight. It turns out there was a burr at the entrance at the front so a little filing did the job. I could have also been impatient putting it on before so that didn't help either.