Exposed cables between bosses.
 

What is the point of this? Instead of just having the sheath go through the boss and running the sheath the whole way?

I think keeping it enclosed would be better. I understand if there was an extra barrel adjuster, but I don’t think I ever see that.

Exposed cables have zero friction in the area where they are exposed

Ok, that makes sense.
Would a sheath the whole way keep the insides cleaner and keep corrosion away longer? So it might be appropriate if the owner was more biased towards low maintenance rather than performance? Thank you.

Call me old school, but I like segmented housing, if only so that I can see and feel how much tension a cable is under. But also, if the cable stops are slotted, you can easily pop the cable free from the frame -- helpful when taking levers off of handlebars or working on rim brakes; you can relieve the cable tension without disengaging the cable from the caliper or lever. I'm also not a fan of the zip-tie method of securing a full-length cable housing to the frame, and those little grommets they make for that purpose are prone to failure and loss.

IMO, the only real disadvantage of segmented housing is that every cable stop provides an opportunity for dirt or water to get into the housing. Since I replace my cables whenever I replace the chain, that isn't really a problem for me.

The good news for you is that a lot of contemporary bikes have gone to using a full housing for the cable's entire length, so segmented housing may soon go the way of friction shifters!

Spiral wound housing compresses under load and decompresses when the load is removed. The longer the housing, the more it moves. This made for slop in converting movement from one end of cable to the other. Before the days of indexed shifting, all housing was spiral wound. Short housing runs minimized the amount of compression, making for more precise shifting and braking. Friction was also an issue, particularly before lined housing was commonplace.

In that light, quality bikes had brazed on cable stops, while cheap bikes ran housing end to end. It was once a distinguishing feature.

With better and even compressionless housing, it's less of a concern. Cable stops still have the image, to some anyway, of quality.

Learning a lot. Thank you.

People left out that it reduces weight. Less housing=less weight. But really to reduce friction as mentioned above.

I didn’t think about the housing compressing.

Now I know what to look for when I buy housings.

I forgot about the wheel change convenience, without deflating a tire or messing up brake adjustment.

For a classic 2x road bike with down tube shifters and brazed on guides near the BB, the only shifter housing at all would be the little section connecting the rear derailleur to the cable stop on the chain stay. It’s really an elegant and light system.

Otto

Got it. And the nylon guide under the BB?

That's the item that always worries me. I see people's bikes after they've been riding on the bike path after heavy rains and their bikes are always splattered with limestone paste. I wonder what the cable guide under their BBs look like! :eek:

Braze-ons are relatively new. My 1973 British production frame has a 'gear lever stop' underneath the downtube and a cable stop on the drive-side chainstay for the RDER cable. No cable guide under BB - manufacturers made metal cable guides that attached to DT or perhaps ST. No braze-ons for water bottles. This was true for all the bikes I bought, but I haven't bought a bike or frame since 1981.

The damned cable guides can rust and get very ugly.

My cx bike (like nearly all cx bikes) runs full length cable housings. All of my hydraulic brake lines are full housings, too. ;)

For the reasons I would assume? Prevent dirt and water inclusion?

An open hydraulic brake line is when you wedge your shoe between the seat stay and rear tire, and get yelled at by your parents for ruining brand new shoes in one afternoon.

Huh. If I ever see a bike like that I’ll check it out.

It's just another burden us C&Vers have to bear. :) I really wish I could cheaply and easily use a plastic cable guide under the BB. (I don't want to tape a hole into the BB.)

Pretty common for 1970s mid- to lower-end bikes. Mfgrs would use the same frame to build both a drop- bar “ten-speed” and an upright 3-speed ‘lightweight’.
Thats why you see features like semi-horizontal dropouts, clamp-on down tube shifters, and nice derailleurs like V-GTs with ‘claw’ mounts.
They just used a combination of full-length cables an clamp-on cable stops for whatever style of bike it was going to be built as.

I utterly hate the under the bottom bracket routing of exposed cables. Basically you subject them to operate in the state of pushing against sand paper. It has been the location for me where troubles with cables started. When deciding that I will not tolerate what the bike companies impose on me, I first put the cables in full length housing expecting, what the folklore was saying, that the shifting will get worse and brakes will get harder to operate. The shock was that there was absolutely no difference when I switched to full length housing, maybe it got a tad better. Now, these days I go with linked housing and it is a revolution. A complicated long routing with sharp turns works about as well a short run of a cable.

The downside to full length hydraulic housings is the added weight and lack of air cooling.

As an aside. There is some kind of heat sink that can get put on crotch rockets between the banjo fitting and the caliper, made of AL, the dot4 goes through it.

Somewhat related. I’m not fast enough to fade brakes, but it’s an interesting idea.

The only time I have had cable corrosion it was in the section that was housed. The mousing traps grit and moisture I suppose. I have since made lubing cables as part of my maintenance routine. It's easy to shuffle the segments of housing out of the away and rub an ever so slight amount of marine grease on the cable once a year. It works great.

Two sided gorilla tape.

Epoxy if you're sure.

Well if you’re that particular about it... I have to ask what you’re going to be selling, because I want to buy my vintage bike from you.

Size 18” MTB sizing. Never ridden a road bike more than 2 circles in a parking lot.

You’re probably a good enough mechanic to know this already, but maybe drill and tap. When you’re done with the experiment screw a grub screw into the hole flush, putty, sand, and paint over?

My preference is for interrupted cable housing. Makes servicing cables easier, provides better brake feel, and it looks better. Two of my vintage bikes have full length brake cable housing held in place by cable clamps. That is the way things were done back then. Since the brake housing is spiral wound it has more sponge feel to the rear brake than other bikes with interrupted housing.
FWIW, full length housing for brakes and derailleurs still get dirt or corrosion in them and need servicing, especially on mountain bikes.

Thank you all.
I’ve learned a lot.