mstateglfr 

Curious to hear if anyone has a theory or actually knows why back in the day some bikes were built with cable guides for the rear brake cable, other bikes were build with cable stops atop the top tube and other bikes were built with cable stops under the top tube.

There are many ways to skin a cat and apparently just as many ways to route a brake cable.

Is there a benefit to 3 cable guides on the top tube and one long continuous housing? I would guess compression reduces effectiveness, though I can't say I have noticed it much between bikes.

Looking at it from an economic perspective, the cost of 2 cable stops can't really be more than the cost of 3 cable guides, right?


Cables routed on the top of the tube make sense if the bike is meant to be carried(cross for example).

But other than that, what was the benefit to full length housing and cable guides instead of using cable stops?

noglider 

Small differences in cost are very important to manufacturers, so you can't dismiss them as insignificant.

OldsCOOL

The older bikes had cable clamps on the top tube. I prefer the guides just like I prefer braze on shifters, bottle cages, etc. Style, convenience and evolution of the bike.

mstateglfr 

Sure, over the production run over X00,000 bikes, little costs add up.

I phrased it poorly, but I can't seem to find a correlation between high end bikes and one way or cable routing compared to entry level bikes.
I would figure the cost saving approach would have been typically used on entry level frames.

But I've seen entry level with cable guides and cable stops. I've seen beautiful high end frames with cable stops and cable guides.


Wasn't sure if anyone knew the rhyme to the reason and why one way was chosen over another on any given bike.

gugie 

If the cable guides are on the top, your sweat can build and are attracted to the guidees through capillary action. You see lots of vintage bikes that are rusted there. Regular maintenance, of course, eliminates that.

Open cable stops on the bottom of the top tube are places for water intrusion into the cable housing. If you throw the bike over the your sholder to carry it you're grabbing onto the cable. But you have less housing to compress, and a nominally stiffer cable routing.

Then there's the "hidden" cable that you see on french constructeur and higher end Italian vintage bikes, as well as many or most carbon fiber bikes nowadays.

But, meh, not enough to worry about one way or another.

79pmooney

I like the cable guides on top, continuous housing because it 1) you can pick the bike up by the top tube and not ever have to think about the cables and paint and 2) minimizes housing openings and rust and 3) adds some compression to the rear brake housing, making less effective relative to the front and making the braking front and rear more uniform.

I never sweated enough for sweat on the top tube to be an issue. (I also ate a low salt diet in my racing days and have tried to keep my salt down since. Means my sweat has never been exceptionally salty. I did it to stay away from sodium depletion issues on hot days but it had other benefits too.)

Ben

Salamandrine 

Yeah, it's basically a style issue. Cable stops are theoretically stiffer, since there's less housing to compress. Full length housing on top makes it easier to grab your bike and put it over your shoulder, as mentioned already. Early mtn bikes with cable stops often had them on top to avoid that issue.

If using stops, exposed cable will tend to slowly abrade the paint next to it, and they should be covered with lining.

RobbieTunes

6 of one...etc.

I do like top tube cable guides, mainly for carrying or storing the bike on certain kinds of racks.
Otherwise, I'm a fan of the 7 o'clock stops front and rear, open in between. I just like the way they look.

I like seeing the cables. Makes me feel...industrial.

Barrettscv 

More ways to skin a cat. Cyclocross style;








Internal;

noglider 

It's true that cable stops allow water into the cables, but it's worth that inconvenience to me. I like cable stops better than full housing, because it works better. I can either remember to shoot oil into the openings or lube the cable or replace the cable periodically. I just like the way they work. I can feel the difference in stiffness. On the other hand, if a frame came with cable guides, it wouldn't be a deal breaker. It's just a weak preference.

seypat

Some of the racks today have that arm that tightens over the TT. Not good for the top routed cable.

Miele Man

The miminal amount of cable housing will yield the miminal amount of loss to friction.

Full length cable housing = more friction

Under the top tube cable stops = less friction. BUT a more severe bend to the brake. Also the stop can dig into a shoulder when carrying the bike.

The top tube cable stops removed the problems with the under the top tube cable stops.

BTW, many wish that bottom bracket and chainstay cable guides/stop were still on top rather than under because the under ones are more prone to fouling by road/trail crap.

Cheers

catgita

Cables along the top tube are more protected from dirt compared to downtube, so MTB and cyclocross tended to do this.
Continuous housing is not nearly as stiff, but does keep the weather out.
Less labor cutting housings and less brazing.
Clamps instead of brazing is less likely to heat affect the tubing.
Also a bit of tradition here, because Rene Herse had been doing braze on stops since the 1930s, but most bulk manufacturers continued to use bolt on stops and housing clamps up thru the 70s.
Allows more flexibility in mass production where the same frame can be set up as several different styles of bikes, such as a 3 speed or 10 speed, road or cyclocross, touring etc. all with a generic frame.
Having it above instead of below the tube facilitates carrying the bike on the shoulder, but roadies like to sit on the top tube, so it is rare on road bikes.

mstateglfr 

Interesting responses.

This is one of those things that you don't think of until it suddenly crosses your mind because of dealing with it.
I hadn't realized, but most all the full housing cable guide bikes I have refurbished had rusted guides. Some were better than others, but it seems all have been rusted. The latest project has rust marks along the top tube from the housing, even.

tolfan

lets not forget the inside the top tube routing

T-Mar

Full length brake cable housings run along the top tubes are a traditional feature of racing bicycles that goes back to circa 1910. Full length housing had several practical reasons at the time.

Racing bicycles have always pushed acceptable weight limits and consequently manufacturers have used the thinnest tubing possible. Framebuilders were leery of brazing on any additional fittings that would result in extra heating and possible failure of the tube. This philosophy gained even higher priority in the 1930s, with the introduction of several, even thinner gauge tubesets, such as Reynolds 531 and Accles & Pollock Kromo.

Initially, the housing was taped to the frame and this mandated full length housing , as it could slide back and forth under the tape. Full length housing also made cable replacement easier, at a time when riders had to perform their own repairs.

Eventually, clamps replaced tape but most builders were still reluctant to braze additional fittings onto the tubes, especially in the thinner central regions of butted tubes. It was OK to tack cable tunnels onto a thick BB shell, but clamps remained standard for rear brake cables, shift levers and bottle cages until the 1970s.

Conceivably, things should have changed in the 1950s with the introduction of lower temperature silver solder. However, the reigning framebuilders seemed more interested in maintaining tradition. When cable tunnels started replacing clamps in the late 1970s, they could easily have gone to cable stops but single length housing made it far easier for a team mechanic having to service a dozen bicycles at the end of a long day.

Meanwhile , the entry level bicycle did not have these restrictions. Overheating was not nearly as big a concern when dealing with thicker tubes and the use of stops had a slight economical advantage. The most economical approach was actually to use full length housing held in place by quick mounting spring clips but these moved easily and scratched the finish. Consequently, they were restricted to department store level bicycles.

There are several other minor pros and cons to each system but I believe the rationale for the use of full length housing on racing and high end bicycles originated in preserving the structural integrity of the frame and ease of maintenance.

jrm2010

Anyone know if it's possible to convert 3 x cable guides for full housing to use for 2 x cable stops plus split housing?

I'm thinking of something that would fit into the two outermost existing guides not simply new stops which wrap around the tube.

I'm rebuilding an old koga frame whith with modern groupset for commuting purposes and am now finding I'm wanting to tweak more and more of the fine details!!

Cheers, James

juls

Don't know that I've ever seen cable stops on the top of the top tube... (exposed cable) Was there such a thing? Many a time I had to shoulder my bike with 'exposed' cable beneath. Manufacture w/o understandage of usage???

mstateglfr 

Earlier in this thread, Barrettscv posted a couple picks of an early cyclocross with 2 exposed cables atop the top tube.

Below is one of my wife's bikes- its a 90s rigid frame Scott MTB. You can see the exposed cables on the top of the top tube. Both shift cables and the rear brake cable are located there.

fietsbob

the open cable between brazed on stops .. the shorter length of housing to the rear brake was a bit less compressible.

front brake still is the most effective, so difference in rear performance was not that important.



I have a Rohloff , its 2 gear cables run thru housing ... all the way, they stay clean in there..

ditto the housing run to the mechanical disc brakes..

juls

Good to know! Have never seen-but I'm an old coot so........

fietsbob

this a brazing then repaint project? If so that can be done..

79pmooney

I strongly prefer full length housing on top for several reasons. Makes picking the bike up easy. It is away from the top tube mounted pump. It looks clean. It goes a long ways to toward making the rear brake less effective and therefore a better match to the front. And there are fewer cable housing ends to introduce rust and other issues. (With full length cable housing, the only open cable end is at the brake, pointed down. If you ride with fenders, the greasing you do when you set it up last a long time.) Oh (edit), the cable is far less subject to damage and kinking as well.

Ben

jrm2010

ok, thanks all

no brazing/repaint so i will stick with things as they are!

eschlwc

road bkes are to have full housing in a contrast color clamped atop a level top tube leading to non-aero levers.