Crast

A front brake, sure. You'd just have a taut cable run coming straight down from your levers down to your front brake. I've seen ghetto setups like that, especially on fixies, even for caliper brakes. But what about a rear brake? If you tried to run it without a housing, regardless of how you routed it, if it was tight enough to be useful then as soon as you turned your handlebars to the right you'd actuate your brake. That or start to rip your handlebar tape off, if you had the brake cable routed along the handlebar. Turning to the left would cause the brake cable to become slack and useless (this all assuming the brake cable routes along the left side of the top tube).

The use of housing when operating a canti (or any brake) is to allow the cable to become taut while resisting the cable's tendency to deform first and take the shortest path. In this, force is applied along the inside and ends of the housing, a simple application of newton's third law. It may be directed in many directions along the length of the housing as it curves, but the total force adds to the same. What's causing this "equal yet opposite" resistance? the cable housing stop itself, actually. Even with a cable stop at the rear brake bridge and one at the front of the top tube, you need a housing to go between your top tube and handlebars unless your brake lever is attached to the top tube, simply to allow for turning of handlebars while retaining efficacy of your brake.

Leyczo

I can see what you are trying to say, but it is still not correct. The compression in the housing is still equal to the tension in the cable. It is true that you could design a cantilever system that does not require a housing, and then, obviously, there would be no compression in the housing, but this is not how brakes are designed.

Think of it this way: if you had a cut in the cable housing, you could pull it apart, and it would result in the brake actuating. If you squeeze the brake lever, to the point that the brakes actuate, it gets more difficult to pull the housing apart, because the compression on the housing increases. This is the whole reason that those inline cable adjusters work.

dirtyphotons

it is my contention that in the case of a traditional cantilever brake with no inline lever, it is not. it's a bit too late on a friday, and i've had a couple too many beers to prove my point tonight, but i'll try to get to it this weekend.

i agree that this is the way inline levers work. but i do not agree that this proves that in the absence of inline levers (or any manual compression of the housing as you describe) that the force of braking is transmitted through the housing of a cantilever brake.

dirtyphotons

i'd like to see a caliper brake where both arms apply force on the rim in the absence of housing.

you're fixating on a comment i made that was beside the point. the point is that the housing for cantilever brakes isn't subject to the same force of braking that the housing of caliper brakes is. i'm not telling anyone to run a cantilever brake without housing.

Leyczo

The problem with your thinking is that you are assuming that the brake lever and the cable stop are solid mounted in relation to each other. If they were, it would be possible for you to be right. However, they aren't(at least in most situations). The ability of the bike to steer basically means that the two pieces are mounted independent of each other. Because of this, all the force is tranmitted by tension through the cable, and is counteracted equally and oppositely by compression in the housing. If you were to disconnect your handlebars from the bike, with the brake lever attached, you could still apply the brakes with just as much force as if they were connected, right?

flargle

1. Cable tension is constant along the length of the cable.
2. Housing compression is constant along the length of the entire housing, including at the housing stops, whether the stop is connected to the frame or to a brake arm.
3. Cable tension and housing compression are exactly equal. If not, the housing and cable would simply deform until they did equalize.

svtmike

It took a while for Jagwire to respond, but here's what I got back from them --

So there you go.

thirdin77

You were right.

I got my Travel Agents from Excel Sports for $41 incl shipping. Since mine have barrel adjusters which makes the Travel Agent "taller" than those without, they were the same length as my oem noodles so I didn't have to use longer brake cable housings as suggested by the TA's installation instructions. However, since I am using the TA's as brake doublers, I needed newer, longer brake cables.

Also worth noting was that while the instructions state the the Bridging Hole should be at the 2 o'clock positon, mine's more like at the 1 o'clock but it works fine.

So I got what I wanted- the ability to run my pads farther from the rims to make brake disconnection and wheel removal easier but when the brakes are connected, I have about half as much brake lever travel as before.