Drag From Internal Brake Cable

[bobscott]

I have an early CSI with the rear brake cable run inside the top tube. It looks beautiful but no matter how I have run the cable there is a small amount of drag. I can both hear it (sounds like the cable is dragging on the internal metal tubing) and the rear brake lever doesn't have the nice snap of the front lever.

I have rewired it several times both with and without ferrules and it makes no difference. Pulling on the housing to change the route of entry or exit does not have an effect either so the drag spot seems to not be at the these points.

Is this just the nature of the beast or is there some way around this?

Thanks,
bobscott

[David Kirk]

Do you have some lube of some sort on the cable where it passes through the internal? Light grease or even chain lube can work well.

dave

[bobscott]

I had hoped you would respond, Dave.

Yes, it is well greased; even tried different greases and Rock and Roll cable lube.

It is not a really big deal I just notice hope snappy the rear brake lever is on my other full housing bike. I really love my CSI and want everything just so on it.

bobscott

[zap]

I have bikes with internal routing so have some experience but I don't know how the Serotta is built.

Was there any sign of gunk or rust on the used brake cable when you pulled it out? Is the plumbing designed in such a way that it's possible the cable "sawed" the internal bits?

[bobscott]

Thanks for the input, Zap.

Everthing looks to be in order...clean no signs of wear, rust or damage.

This bike has been dearly cared for by me and it's previous forum owner.

bobscott

[zap]

If a liner fits, try a brake cable kit that uses a liner, like Gore, or purchase plastic tubing from HD or Loews.

[DHallerman]

Are there different sorts of setups for internal rear brake cables?

I ask because I have a Ritchey Road frame with internal rear brake, but I run the complete housing through the top tube. That makes it like older road bikes, which had external stops that required full housing.

And with a lubed cable, I don't really notice any difference than with external stops and bare cable along the top tube routing.

But it sounds like the OP runs bare cable through the top tube.

Dave, who prefers the external method for function even though the internal method is clean looking

[David Kirk]

Serotta internals are made with a brass inner tube that allows for only the cable to pass through and stainless ends that are brazed into the top tube that hold the housing. So I think you'll find that there is no room to feed a liner through there.

If it were mine I'd make sure that there are no burrs or sharp edges where the cable enters the brass tube and I'd use a compressor to blow out any old dried up lube or grit. You might try flooding the internal with spray WD40 to loosen old grease up and flush it out. Then I'd install a new lubed cable and it should work well.

Dave

[bobscott]

Thanks to all, especially the "voice of experience", Dave Kirk.

Busy these days, so it will be a while before I get to it but I plan to do the WD flush after checking the intertion areas for burrs as Dave suggests.

I will post the results.

bobscott

[bobscott]

As Dave suggested the problem was due to some sort restriction/burr inside the tubing. I masked of the ajourning area and went in with a small round jewlers file. I smoothed all the edges and now there is little to no extra drag on the cable.
Thanks to everyone for the input on this and a special "shout out" to Dave Kirk.
bobscott

[RudAwkning]

heh, heh....heh.....Dave said "lube".....

http://www.youtube.com/watch?v=WE3s_jylTOU

[David Kirk]

As Dave suggested the problem was due to some sort restriction/burr inside the tubing. I masked of the ajourning area and went in with a small round jewlers file. I smoothed all the edges and now there is little to no extra drag on the cable.
Thanks to everyone for the input on this and a special "shout out" to Dave Kirk.
bobscott

Cool.

Smooth braking is good.


Dave