Friday, April 5, 2013

Building My Bike: #8 Cables

Stretching new cable.
What makes me the most nervous about any kind of project is doing something permanent. For example: cutting. For this project, that includes cutting a chain, cutting bar tape, and cutting cable. I try to cut long when I can because my fear is cutting short and ruining something, which means I have to spend more $$. Nervous.

Stock ferrule didn't fit.
Don't go without ferrules.
I started with the brake cables because I thought they would be the easiest and they were. Route them through the brake handles, run them through the housing and then through cable guides, hook them up to the brakes. Done. Something helpful to do, though, is stretching the cable. Once the cable is hooked up, grab a section and pull on it a few times. Then go back and tighten it up again. Cables stretch, especially when they're new, so pre-stretching as much as you can does help.

A step-down ferrule.
Another helpful tip is don't use the wire-cutters you may already have. You are not going to be just cutting cable but also the housing, which is plastic on the outside and metal underneath. Traditional wire-cutters can cut the cable but squish the housing. Get yourself a cable and housing cutter. Mine is made by Jagwire and it also does endcap crimping.

Perfect fit.
I had a bit of an adventure with the cable housing ferrules, those metal things you put at the end of a section of housing. The ferrules that came with the cable housing did not fit the cable guides on my frame. They kinda went in but didn't fit well. So, I thought I would try to get away with not using ferrules. Bad idea. Stupid idea. So I put the ferrules back on but wasn't happy. I did some internet searching and found some step-down ferrules. I went to a LBS to see if they had some, they did, I put them on, and they were perfect.

That bit of daylight is
where the cable goes.
The shifter cables were a bit more of an adventure. I started off by having a hard time figuring out where to start running it through the shifter (I should mention that these are Shimano Ultegra shifters). I should have taken a picture of where I pulled the old cable out. I figured out the right opening and ran the cable through it. However, it wasn't smooth going. I kept pulling on the cable, though. I knew I was in trouble when the cable stop kept going. It actually got a bit stuck in the shifter. After taking a few things off the shifter (those things are pretty complicated and don't disassemble so well--which is why they're so expensive), and some luck, I was able to pull the cable back out. This time I turned the bike in the stand so I could take a good look at the bottom of the shifter. See that hole in the bottom left? In there is some daylight. That is where the cable needed to run through. Once I figured that out, the cable went in smoothly.

What a cable stretcher can do
if you're not careful
The cable to the rear derailleur was easy: run it, hook it up, stretch it a bit. Piece of cake. The front derailleur, though...

Let me admit that the front derailleur has always been my nemesis, even when installed by a bike shop. It would stretch and I'd have to pull it but I would screw up and shifting up front would suck for a while. Same thing happened here. I installed the cable but I couldn't get it tight enough, shifting would be okay for a while but it wouldn't take long for the cable to stretch (I could never seem to stretch it enough), so I'd pull the cable some more, I couldn't get it tight enough, shifting would be okay for a get the picture. Clearly I was missing something and that something was a "cable stretcher" or a "fourth-hand tool". It's a clever little tool (mine is from Park Tools) that grabs the cable, lets you pull it tight, then lock that pull in place while you tighten the bolt. If you're not careful, though, you can mess up your cable while using it so let me give a few tips:

  1. Do not cut your cable until after you have used the stretching tool to install it. Even then, you'll probably want to cut it long the first time because it is going to stretch and you are likely going to have to pull it again. You do this because the cable won't fray as much if it is whole. If you try using it on a bare cable end, see the picture above.
  2. If you do cut it again, make sure you leave enough length to use the cable stretcher well-within the end cap. You don't want to knock the endcap off while you are using the cable stretcher. See the photo above.
  3. For the front derailleur, set the inside adjustment screw about midway. Once you install the cable, you are going to be screwing it in so make sure you have some room to do that.
  4. Set the chain in the largest cog in your cassette and the small chainring. This is as far in as your front derailleur will be going.
  5. Using the cable stretcher, pull the cable so your front derailleur is as close to the chain as possible. Though we will be using the screw to fine-tune the adjustment, you don't want to make a big adjustment with it.
  6. Lock the cable stretcher and screw the cable down.
  7. Stretch the cable with your fingers as much as you can. More than once.
  8. Repeat steps 5 and 6.
  9. Lastly, don't squeeze the tool with a death grip. It is not needed because with this tool you don't need that much effort to stretch the cable. If you squeeze too hard you can fray your cable even if you haven't cut it yet.

Since I used the cable stretcher my front shifter cable doesn't have slack and it shifts just fine. There is still some slack in the rear brake cable but I am not sure what I can do about that yet. The brake works just fine but when I go over bumps the cable slaps against the frame, which isn't harmful but it is annoying.

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