I am switching a Team Fuji from Aero to non-Aero brakes. I have all the components needed, and I have to decide on the proper routing. How much slack should I have in the cables above the bars? Should I max out the stem height and adjust for that? Or just go by where the bars are comfortable to me? Unfortinately I can't just go by the original cables.

Here's an example of a Team Fuji with non-aero.

I would set the stem where you will be comfortable. Leave enough of a "loop" so there are no sharp bends even when bars are turned side to side. Just an aesthetic thing- I try to get cables to "cross" directly over stem when looking down at it. (OCD?)

There is no fixed rule for housing length. That pic looks good as a model. The thing about bar height is unless you are using a really long stem the difference between stem up or down isn't so great as to make the housing look odd. Just get the bar dialed in roughly where you'll ride it then install the brakes to look like that pic. The only real error could be that you make it too short so that raising the bar (literally) pulls the housing tight. If you make it long you can always cut it later if you need to.
[MENTION=455882]Bianchi84[/MENTION] makes a good point about turning. That pulls the cables tighter than raising the bar generally would.

In that pic the cables appear to run in front of the bar. Some of us, perhaps almost all, would say they should run behind the bar. It's a tossup about whether the rear should run to the left of the right of the stem.

"I've cut this cable three times and it's still too short."

Interesting. Almost every vintage bike I have ever seen has the cables in front of the bar. Is there some advantage to switching or is it just aesthetic?

I don't know that there's any rule. As suggested in earlier posts, they should be only as long as they need to be.
I know that I have a tendency to make the cables longer than needed, so I try to keep an eye on my old catalogs and use them as a guide.
For instance, this shot of a Raleigh International is a typical example...



As far as whether the cables should be in front or behind the bar, I run them behind. Of course, my stems tend to be 100mm or so. With a much shorter stem, the smoothest routing might be in front of the bar.

Steve in Peoria

From Sheldon Brown:

The Four Commandments of Cable Routing:

1. The handlebars must be able to turn as far as they can in both directions without being limited by a cable pulling taut. Instead, the turning limit must be set by the handlebar bumping into the top tube or by the brake arm or reflector bracket bumping into the down tube.
2. No wrong direction bends (For example: as the rear brake cable leaves the top tube and makes the bend down toward the caliper, it should make a smooth transition from parallel to the top tube to parallel to the seat stays. If the cable bends up from the top tube before bending down toward the seat stays, it is probably too long. If the cable curves out past the caliper, then bends back at an angle more vertical than the seat stays, it is certainly too long.
3. The bends that cannot be avoided should be made as wide (gradual) as possible,
4. Cable housings should be as short as they can be without violating the above rules. If a housing is attached to a part that moves, test it at the extreme positions it will take when in use. Apply a brake; shift a derailer to the positions where the cable is tightest and where it bends the housing the furthest in each direction.

More here.

My rule is what counts and the first criteria is to have the bar at the right location. Second is to have the cables as short as possible with the maximum radius and minimum bends. As stated, the stem will dictate if the cables run in front or behind the bar. I am one of the few with the front brake controlled by the right lever. The result often is that the cable don't cross. WRT the rear cable rounting around the stem, it is determined by how much the cable is "stretched" when turning the wheel.

In addition is the issue of the rear brake cable housing from either the clamp or exit of the tube to the brake. My preference is not to have it bend up to go down. The criteria for me is to avoid the cable rubbing on the frame. If the rule for the front is followed on the back then it will rub on the frame, depending on the exit location of the clamp/tube exit.

Having been so straight forward in the above comments, I don't really care too much how other do it. To me it is all about cable/housing performance with economy of cable/housing length, in that order.

I run mine in front of the bars on my main bike because going behind put a bad kink in the rear housing. I'll probably change it when I get a longer stem.
Most of the bikes that had stem shifters were routed in front to prevent clutter. That's my understanding anyway.

Last detail has to do with how the cables cross above the stem extension. I usually find that if they are crossed one way, that the housings touch and remain in contact.
But putting the other cable in front may leave the two housings separated by some distance, often with one of them clattering against the handlebar or stem.
My preferred way here is to have the cable housings touching, and with the front brake housing in front of the rear brake housing where they cross before going to each side of the stem.
This is for non-aero cable routing of course.

The rule(s) I was taught to follow were the same as the ones Sheldon wrote as quoted in post #7 . Basically you made them as short as possible while still being able to fully turn the bars in both directions until they touch the top tube. I'd usually give them an extra inch or so beyond this, to allow some trimming in the future as the ends got mangled. This method is/was possibly influenced by Eddy Merckx, who was famous for his extremely short cable housing. Also, unless there's very good reason to do otherwise, cables should be behind the bars. Generally speaking, you just want the smoothest most logical and shortest path from lever to brake.

The cables on my personal bikes almost never cross, because I've always hooked them up Italian style - right hand front brake.

Never saw the reason or logic to route cables in front of the handlebar.
Not sure why people still consider doing such.....

The bike in this picture is a small frame with a short stem, so putting the cable behind the bars would bend the rear more than necessary. Also, the front cable aligns with the brake by going in front of the bars.
Larger frame sizes tend to also have longer stem extensions, to the "behind the bar" rule makes more sense.

I always try to run cables behind the handle bars.If they cross over the stem, i use hemp and tie them together and finish with a coat of wood glue(clear) over the hemp. As far as length, I make a fist and vertically slide it under the cable for gage length. No set rule , it just seems to look correct, IMO. Joe

Not just aesthetic. My experience on every bike I've ever built is this. For the rear the housing runs forward horizontally from the TT on one side or the other of the stem or HT. It also has some amount of its own weight. The combination of its weight and the stiffness coming off the TT make it want to drop before somehow going high enough to enter the lever from above. If it isn't supported it ends up with a bend where it enters the lever, essentially trying to enter the lever from the inside. The longer you make the housing to open up that bend, the heavier it is so the more it wants to sag. It may not look that way in ad photos where the steering is pointed straight ahead, but when you turn the handlebar toward whichever side the lever is mounted it falls down and kinks the cable at the lever. When routed above the bar it rests against the back of the bar. This give it a slightly sharper bend upward off the TT but this bend is still less than the kink it can develop at the lever. You can experiment with whether it should go on past the stem on the side with the lever or on the other side. I can't remember which way I do mine, and it sort of depends on how you run the front and whether the TT has braze-on housing eyelets on one side or the other.

On my bikes the handlebar always sits ahead of the front of the fork. So for sidepull brakes routing the front cable behind the bar means it drops straight down to the caliper. By choosing whether you run it across the rear cable you can make it help keep the rear cable in place too. FWIW, I always have the front brake on my left hand, and my sidepulls have the cable on the right, so the cable always has a smooth loop over the top, left to right. For centerpull brakes the hanger tends to be directly below the stem extension but still behind the bar. Looping the cable over the stem to enter the hanger from the opposite side gives it a nice smooth bend.

That's probably because it's been 30 years + since non aero brake levers have been standard, and people no longer know how to set them up.

I can assure you that the vintage correct way is behind the bars. There were always exemptions for personal preference - anyone can set up their bike however they like, but no bike would have left a professional shop floor with cables in front.

You might be right, but a good number left the factory with cables in front of the bars, especially the front cable.

Whether a bike has stem shifters, centerpull front caliper or a stem shorter than 8cm or so can affect where the optimum cable routing position will be.

I've surprised myself a few times, when I ended up routing cables in front of the handlebar for one or more of the above reasons.

None of the bikes I ride has a stem shorter than 8cm, so I route the cables behind the bars even when stem shifters are used.

I don't think that the factories were always very particular about where the cables on boom bikes were routed, as evidenced by some of the catalog photos, and I think that it's possible that simple things like packaging/shipping concerns could have swayed the decision on how cables would be routed.

What I'm gathering from this is, there is no "right" way. Every bike is different, and you need to respect that. A lot of good points were made.

You can always try getting your hands on a Specialites TA brake cable guide (Velobase).



More info in a previous thread or here

Way back, racers went as short a bend as possible. Very little arcing over the bars. I went with what would keep my hand from snagging the cable housing as I raised it to scratch my nose. I bought one bike with the super short cable approach, took a while to train myself to swing my hand clear of the cable when raising it, too much effort.

A Big arc does look tourist. But who is racing?

I suspect housing was a lot more compressible back then too, so you'd want it as short as possible.

For the record, the factories didn't have much to do with cable routing. Bikes arrived at bike shops disassembled and in boxes. The LBS assembled them and made any determination about cable routing.

More often than you would think, catalog shots had poorly assembled bikes in the product shots. Presumably this was because they dragged bike boxes to a photo studio, without getting them professionally assembled.

It's true sometimes Peugeot shops would route cables under, especially older ones with under TT routing. They were an exception. May have been more sloppiness than preference. Schwinn may have had guidelines, but I never worked in a Schwinn shop so I don't know.

As far as I can tell this was midway through the restauration of that bike and I don't see any leftover threading in later pictures.