jonwvara 

I've never owned one, but I've always been suspicious of frames that route the rear brake cable through the top tube. That was what, a late-80s to mid-90s fad? It seems like a great way to get water into the frame, introduce a stress concentrations as a place for cracks to start, and it looks slightly dumb (okay, that's a value judgement). Also, what do you do when the little plastic fittings that go in the holes bust or get lost? It can't be easy to find replacements.

bumperm

I have both, and prefer the cable run inside the top tube. This, on a Trek Madone, provides a "cleaner and neater" installation. Given how much effort Trek put into this frame design, I'm sure they insured the holes are not detracting from strength or longivity. If the little plastic thingies ever break . . . not sure why they wouild, and Trek no longer stocks them, however unlikely that may be, I'll make my own. I'm sure any machine shop could do the same.

bumper

John E

I have never liked the concept of cable-through-the-tube for the reasons mentioned above. I have an equally silly cable-through-the-stem front brake setup on my mountain bike.

stronglight

Gee, I always liked that cable-through-the-stem mounting... perfect for cantilevers or center-pull brakes if you don't want the clutter of additional hangers stuffed into a headset stack.

...but, I'm not familiar with the MTB style... in fact, I can't really even imagine how that would work since brake cables would be coming from either the side or below the stem. ~ That DOES sound rather odd.

unworthy1

well, the fad caught on in late '80s, but you can find examples dating back to the '40s and probably even earlier if you know where to look. The problem with the early attempts (and some of the late ones) is that the openings were crudely finished, sometimes with big flanges or grommets, and that could let moisture into the tube. The worst was if the cable was run "blind" through the tube and you'd have to fish around for the rear opening to get it through: terrible idea! Later versions solved this by brazing in a solid cable guide tube from front opening to rear and "frenching" (that's what the car guys call it) the openings so the housing slides in clean and snug...it still adds weight (and building complexity) to the frame just for effect, but if it floats your boat...
I like those early stems above: very neat solutions!

stronglight

I think the latest iteration was born of the early 1980s "Aerodynamic" racing bike frames - such as the Cinelli "Laser"

... But, I've seen some VERY slick treatments on custom built French Touring bikes from the 1950s!

Those however had beautifully hand formed brazed-on entry tunnels and were definitely works of art, and those were very costly and labor intensive options. One example even had the cable for the rear cantilever brake routed THROUGH the seat tube and included a slot milled through the seatpost to finally exit the cable at a perfect location through a "spout" at the rear of the seat tube.

Here is a more modern TOEI version inspired by the Rene Herse original concept. This bike too was made to measure. So, why NOT bore through a seat post - which will NEVER require a lot of up and down movement...



Here is a one-off 1950s Peugeot prototype show-bike (which never saw a production run). The internal cable makes PERFECT sense here for the center-pull brake along the diagonal tube, behind the seat tube. And notice there is also an internal derailleur cable for the single shifter, which exits just ahead of the rear derailleur. Brilliant and elegant designs, FAR ahead of their time (IMHO)... even though this welded steel frame surely had weighted a ton!


I think carbon fiber (as bumperm mentioned on his Trek Madone) would be the perfect medium for internal routing since the resin impregnated CF wrap could be very smoothly integrated into the frame design, and there would be little concern about stress risers.

jonwvara 

Okay, "cleaner and neater" is another value judgement, and I guess as valid as my own. The plastic things will break because plastic things eventually break.
JV

tuz

I think it's neat! I don't think there is an induced weakness since the top tube is the least solicited tube in a bike (along with the seatstays) and in any case the holes are small. I admit there will be increased friction compared to stops or guides.

Like unworthy said the best type is with a brazed tube. Like this. My Gios has the slot/grommet type and it was a pain to fish the cable, but it's nice to see the slot is reinforced.



On some Miyatas and Mieles I've seen, the slot is not reinforced and I admit it looks sketchy to see the thin tube like that. On some cheap Raleights those slots where put on the downtube to route the derailleur cable (??) and I've seen one of those fail.

Stronglight check this other French bike, with similar rear brake routing (and with internal routing all over the place)

rugerben

I have a massive paper due tomorrow. If you can hold out til tomorrow night, or perhaps wednesday I'll take a pic for you. My early 90's GT talera has this set up. The cable enters the stem right below where it connects the handlebars, and then it exits the stem about 2.5 inches below that.

jonwvara 

Thanks for the Gios photo. Okay, maybe it won't crack, but I'm still troubled about water. It dribbles in there, pools on the horizontal inside of the top tube, and...what? I guess it eventually drains into the seat tube and pools in the bottom bracket, maybe even escapes through drainage holes if there are any. But what's the actual benefit? Is a the added "neatness" (assuming that you think internal routing IS neat) worth the risk of structural problems down the road sometime? It just doesn't seem to add up to me.
JV

well biked

My '97 Pinarello has internal brake cable routing through the top tube. It has an internal sleeve that makes it so easy to feed the cable through you could literally do it with your eyes closed. No plastic fittings. I think it looks very elegant, makes the left side of the bike more interesting to look at:

tuz

I'd say the rubber grommets are as watertight as they get: I actually had to pull quite hard to get the outer cable out of the grommet, and to get the grommet out of the slot. In any case it's not the type of bike you ride in pouring rain often

But you're essentially right. There is no real benefit. It's just a detail that sets the bike slightly apart, and I think it looks great. But I really doubt that it induces any long-term structural problems.

TheSojourner

My '87 Raleigh Technium 440 has the cable routed through the toptube. Seeing as how I'm about to replace all the cables and housing, it's a bit of a pain in the ass, but I kind of like the look, so I'm on the fence.

My thought it to tape the old housing to the new housing (if you can't duct it...), and then pull the old one out, which will hopefully will still have the new one following behind it. If this fails/pulls apart, I have no frickin' clue how I'll fish the new housing through the tube. Suggestions?

well biked

There's a fairly current thread in the mechanics forum with some good suggestions.

infinityeye

1. pull the old cable out
2. stick the new cable through from the rear
3. pull the old housing out
4. put the new housing in (the new cable is still threaded
5. pull the new cable out and thread it from the front through the brake lever etc.

6. tighten and you are done!

stronglight

"... Interesting to look at"? I'd say GORGEOUS to look at - entirely!

I'm usually not impressed with rather modern bikes but that Pinarello is really a beauty! A lovely and consistent color scheme throughout the entire presentation from wheels and tires and saddle to cables and bar tape. I even like the simple lettering style of the decals. Nothing like most of the all-too-distracting billboard graphics and grafitti paint schemes one often finds on newer bikes.
Now THAT is a bike which even an old retro-grouch (like me) would not feel at all ashamed to be seen riding!
Bravo well biked - a real winner!

well biked

Thanks for the compliments! It is indeed a wonderful bike, and it rides as great as it looks. Here's a link to a thread I started on it recently, with more info on the bike:

https://www.bikeforums.net/showthread...=#post7994743:

ollo_ollo

I have 3 frames with this feature: The holes are brazed on the lower quarter of the top tube with an internal guide tube & I don't see how any water could flow up into the tube or get past the brazing. No "Plastic Thingey" to break, just a metal stop for the sheath at each end, & as well biked says, very easy to thread the bare cable through. Two of mine have flush entry holes and one has streamlined stops on a diamond base. the drag feels the same as other frames which use a cable stop at each end with a bare cable running outside the tube. Don

-holiday76

I dont have much input except that in mine the cable housing fits into the first few millimeters of the hole in the tube so no extra parts are needed to make it work. You can't really tell from this pic, but hey, I get to show off my new brooks pro

RobbieTunes

+1

I'm with Pinarello. I think the top tube internal routing on the Montello was as clean a treatment of cable routing as has been done. And if you look at their new collaboration with Eddy Merckx, well, it's eye candy if you like modern.....

Now, my latest single speed project (a Caloi) is a great example of it done wrong.

wrk101

I am not looking forward to the oxalic frame soak I need to do on my PE-300, which has the rear brake cable routed through the top tube as well. I probably will leave the existing cable rather than the jacket prior to the soak. The oxalic should not affect the cable (although I will toss it regardless). I would think the cable jacket would be a mess soaked in oxalic.

Old Fat Guy

I no longer own this bike, but I really like the way Tom Kellogg did his cable entry

unworthy1

^that's^ what I meant by "frenched"...my Ciocc has it and I'm perfectly happy, YRMV

Elev12k

With one of my Zielemans it runs slotted under the tt. 'En profil' you won't see the cable, but there is no opening in the tt, so water won't enter and ...and servicing is easy.

Have the same slotted construction on my Vitus CL1 MTB frame.

martl

I've seen frames from the 50ies with interior brake cable routing.
You'll always get water in the frame anyway, and neither is that really a problem if the builder did his job and drilled some vent holes in the frame.
On the other hand i've seen many otherwise fine frames that started to rust on these spots. But that is not because of water exposure, but most likely due to overheating of the thin segments and maybe insufficient cleaning off the flux after brazing.