BigPoser

It's my understanding that when running internal cables on a metal frame most people run some sort of tube all the way through the frame tube. Is it possible to just have cable stops on each end like carbon frames have? Cables would be hard to run I assume, so you'd have to run liner through before pulling out the old cable I suppose.

Are there reasons why this wouldn't be a good way to do it?

Been thinking about and curious.

Thanks in advance.

Brandon

Andrew R Stewart 

Rust inside the tube and cable slap against the tube ID are two issues I can think of. Andy

squirtdad

FWIW probably need some reinforcement. My '89 Miyata 1400 (RIP) cracked at the opening for the internal cable routing. Known problem with that frame. it had purpose designed plastic cable stops and hole plugger dodads. No rust issues

BigPoser

I could see rust. What about framesaver?

If the cable stops were inset from the outer wall enough, wouldn't that keep the cables from slapping? Much like the cables in my carbon bikes don't slap.

BigPoser

Right. I've seen some pieces at Ceeway that are just for reinforcement. If the cable stops had some overhang themselves and were brazed in, I would think that would be good for reinforcement purposes. Of course I don't really know that much either. Just thinking out loud.

unterhausen

haven't seen them for a while, but there used to be assemblies with brass tubing for the cable and stops on either end for the housing.

how do you run the cable through a carbon frame?

rm -rf

Carbon Frames
Yeah, there's no internal guides on most or all carbon frames.
The rear brake cable on my carbon frame:

Feed thin "liner" tubing into the rear frame hole, near the seat tube. With the fork removed, use fingers to guide the tubing out the front cable hole. Now there's liner tubing sticking out 6 inches on either end, so it's easy to push the brake cable through the liner. Now, either pull the tubing out the back, or trim it to fit inside the frame. (That's how my bike was from the bike store, with tubing inside.)

To replace an existing cable, do NOT pull the cable out of the frame just yet!
For bare internal cable: push tubing onto the cable from the brake end, until it sticks out the front hole. Now pull out the old cable, keeping the tubing sticking out both ends of the frame, and install new the same way as above.

With internal tubing over the cable, neither end of the tubing is anchored. So push on new tubing as far as possible, then "carefully" pull old tubing and cable slowly from the front while pushing the rear tubing at the same rate. Keep going until the end of the new tubing comes out the front. I suppose the tubing was left on the cable to avoid any rattling.

See the photos in my previous post.

long john

Canaboo

I prefer to run tubes for the cables to run in a bamboo frame. It's just easier all around and keeps the interior of the tube totally sealed. I make tubes from small diameter braided sleeves.

unterhausen

I wonder if the brass tube is big enough for an internal liner tube.

I suppose it would be easy enough to fabricate the ends and use another internal tube

dsaul

I have used that tube twice to run an internal brake cable and found that the bare cable rattled like crazy inside. I was able to fit a liner inside the brass tube to silence the rattle, but it was a tight fit to get it past the bends. No more internal routing for me. It looks cool, but makes the bike more problematic to service.

unterhausen

I have never done internal routing. Violates my desire for simplicity. Thinking about it for a bike that intentionally goes against that ethic. I'll probably just run a tube for full-length housing. I have an All City that runs the FD cable through the top tube in full length housing and it works okay. It's nominally a CX bike, so they wanted the cables to be out of the way for ease of carrying. But the bike is so heavy you probably would have problems running with it.

I'm not sure when internal routing started being common. Must have been sometime in the '80s. But there are plenty of pictures of failed frames from builders that took a haphazard approach to it. I even saw one from a fairly recent build using full length tubing and the standard reinforcements that was somewhat concerning. Not sure why that failure happened. I usually save pictures of bike frame failures I find, but I didn't get that one. I'm guessing the bike had really short butts on the top tube.

BigPoser

This is why I posed the question of routing internally without the brass tubes. No rattle if it can be done.

unterhausen

a tube with housing the full distance isn't generally known to rattle.

You would have to get housing stops to line up in a straight line with no bend at the end of the housing or it's going to suffer from poor cable performance. So you probably will not be able to have a good entrance and exit location. I think most of the bikes that just had housing stops at the ends had the entry/exit in a straight line. Think of it as a couple of stops on the top tube, only inside, to see what I mean. The bikes like that had a very high failure rate.

Andrew R Stewart 

At Cyclery North we made a couple of frames with internal rear brake cables using simple open ports (ringed with a reinforcing lip and plugged with poor fitting "rubber" boots). We ram the housing full length. I didn't like the lever pull feel (mushy) and there was casing slap over bumps. In the few months I saw the bike I did, after delivery, there was no known rust... yet. The few Panasonics PICS I sold a few years later at my shop also suffered casing slap. In fact the one that served as the shop sample didn't sell for a few years. We ended up stripping off the parts and sold it as a bare frame after the test ride feedback of "what's that noise?".

I deal with a lot of current carbon bikes with internal routing. Some are not too bad for recabling and in use cable friction. But others should get triple+ the flat rate for a cable replacement due to their designs. Why should a shift cable take 45 minutes to replace? Because the internal routing will make you faster Andy

dsaul

It can be done. There is no reason for the full length tube, other than a guide to run the cable. The only way, that I can think of, to run a cable would be to install a length of cable before joining the frame and then install some liner for a cable guide after the frame is finished. If someone unknowingly removes the liner in the future, it will be near impossible to get a cable through the frame again.

As for the cable slap issue, shifter cables have tension on them and generally won't flop around and slap the inside of the tube. Brake cables are slack, when they are not being used, and can move around quite a bit when you hit bumps.

I think the better question is, why run internal cables at all? If there is some performance reason, then go for it. If it is purely aesthetic, don't do it.

unterhausen

the reason for the full length tube is to stop water intrusion into the tube. But water is going to get in there with the housing, so that's a good reason to use stainless.

Plenty of people build with internal routing, and a lot of riders want it. Granted, it's mostly for looks, but there is nothing wrong with that. Some builders put all the cables inside the tubes, which I always thought was risky. But just running one brake cable inside the top tube is very common, and unlikely to fail if you put a full length tube for housing in there. Otherwise, history says the chance of failure is fairly high if water can get in there. The top tube takes a reasonable amount of stress, so it's a concern.

If it's just for fun, then experimenting is fine. If it's for someone else, I think a conservative, mainstream approach is best.

BigPoser

Yes for now the first several frames I'm building are just for me. I want to be able to try things and learn in the process. If it breaks, it'll be me riding it. Once I perfect it, then I'll put them out there.

long john

unterhausen

https://www.flickr.com/photos/bishop...89348263/page1
not sure I ever wanted a portacana on my rando bike, and running the back brake through the seatpost seems like a bad idea, but that's a really nice bike.

David Tollefson

Yeah, hits me as a "WTF?" kind of thing. What could possibly go wrong?

Cynikal 

The routing through the seat post was an old CX thing. Keep in mind that this was for NAHBS so it was done for effect. There is a benefit of making the seatpost and saddle more theft proof. I am always in awe of Chris Bishop's work. It is amazing.

unterhausen

I know it was for nahbs, but it was also built for someone. There are very few bikes at nahbs that aren't already sold. I am pretty sure I have also seen old French rando bikes with this "feature." I suppose if it was my bike, I might feel more comfortable doing it, because I could always modify another seatpost.

BigPoser

Thanks for that. There's a lot of eye candy to drool over.

Is it better to have stops when running the brake cable internally or just run the full housing?

mikeread

Can anyone tell me what the rubber strip is for on the chainstay? I can only think it is to protect from the chain but it seems a bit over the top for that alone.

Mr Bishop is definitely not from the KISS camp :-)