Or how eveyone else is mucking it up!
In cyclocross, there are a bunch of compromises you make to get a bike working. It is, after all, a sport forged from road racing with just enough mountain biking thrown in, and a few proprietary goodies for good measure. One of the issues people struggle with is front brake cable routing. A lot of bikes are pretty smooshed for space where the front cable exits the bar tape and gets routed down to the front wheel. While there are plenty of ways that will effectively route a front brake cable, they all are wrong. Either they offend my delicate visual sensibilities, are a shoddy and quick way of dealing with a problem, or they have the potential for imminent death. I'll go through all of these "options", but first I'm going to show you the correct way and give you a little trick to make it even better. Do it this way or you are wrong. (Aren't you glad we got that point established? And by we I mean me.)
First, get yourself one of these from IRD.
You won't need the pinch bolt if your headset is tight, so toss it to save a few grams. Sure there are lighter ones out there, but none are better. Because it's machined from a pretty sizable hunk of aluminum and they leave a fair bit of it intact, it's pretty stiff. Meaning your brakes aren't mushy from your hanger flexing. It's a small step when it comes to eliminating brake shudder.(Another post entirely.) Your brakes may still be mushy because you don't know how to set them up, but not from your hanger flexing.
Route your cable under the stem. I don't care how the TreeFarm does it. By using the LongDrop from IRD you'll have plenty of room for the cable to make a nice smooth bend.
If you want to be extra cool like me, use an old V-brake noodle to guide the cable to the hanger. You can bend it into all sorts of configurations and the cable will slide through it better than plain housing. Plus it will help firm up the feel at the lever. If you don't have any old noodles laying around, go to your local shop. Any shop should have a bin full of the never used but always included 135degree bend ones. You can bend it yourself to any angle you want and if you need to shorten it, just pull the end the housing goes into off and cut the tube with a hacksaw.
Here's where I list all the wrong ways and make fun of them. If you route your cables this way and are offended, then good. You deserve to be. Any idjit that gets offended by teasing and brake cable routing posts on the web needs to pull up their big girl panties and have anther cup of shut the fuck up.
Resist the urge to be "Euro" and route the cable over the stem like this.
It's bad enough that the cable is on the right side, thereby giving the rider "motorcycle" or "Euro" style brake set up, but he's using Nokon housing to make a long loop of housing. Nokon, while a pain in the ass and expensive, does have the sole redeeming virtue of being able to be bent into small arc and still have the cables pass smoothly. This bike looks like he did it this way so he could show off the color matching that Nokons allow just a bit more than if it was tucked away under the handlebar.
The real reason you'll see this routing done on some Pro's bikes is because it's fast and easy to do if you are a mechanic that is replacing housing and cable fairly often. It allows for more latitude in cutting just the right amount of housing. If it's a little long, who cares?
Make certain your hanger is on straight. For the love of God, don't do this.
It makes you look like a fat man with a too short and crooked tie. Think Blimpy from Popeye. Again, if you run the LongDrop and noodle, then you won't have any issues with the stem getting in the way. Show some class and get it on there straight. If it's rotating itself, then your headset isn't adjusted properly.
This next one I just hate because of pure aesthetics.
It's ugly, I don't care how many fast guys do this. When you view the bike from the side, the cable is going dow n to the front brake at a goofy looking angle. Also, there are quite a few stems that don't have the clearance between the face plate and the stem body. If your fork suffers from shudder issues, then this will only make it worse.
If you aren't a fat, chain smoking Belgian professional mechanic, then don't even think about this next little "fix".
Drilling through your stem is stupid. Sure, there are posts on the forums with people claiming "no problems so far", but so what? I'm certain there were Yugo drivers that said the same thing at first. The Pro's bikes will have this sometimes done for special events like Paris-Roubaix. It's designed for a one time use. Not three seasons of Cat 3 mid-pack dominance and summer time adventure rides. Besides, it makes the bike look like it has a "Prince Albert". Turn your filters off on your Google Image search and you'll see what I mean.