Wednesday, July 18, 2012

Fuzzy pictures with a clear message

Last week we had a rash of bikes that had developed mysterious shifting problems. Adjusted derailleurs would creep out of adjustment a little more with every shift.
 The fuzzy photo above illustrates how the inner wires of shift cable housing can punch through the ferrule and burrow into the brains of the shifter. They can also emerge from the other end, through the cable stop on the frame. Any section of housing in the system can do this, but it causes the most potential damage when the wires dig into the shifter.
This fuzzy video shows the actual extraction of exploded housing from a brifter and inspection of the shift cable itself for fraying inside the shifter, which can also have expensive consequences. A piece of the plastic liner of the housing has been shoved all the way through the shifter.

If you keep having to adjust your derailleur cable and take more and more cable through the anchor bolt, undo the cable and pull the housing out of all the stops along its route.

Five millimeter housing with beefy metal end caps is the least likely to fail in this manner. Cheesy OEM 4mm with plastic caps is the most likely. You decide.


Matt Boulanger said...

I was very surprised to find my recent Jagwire re-cable kit had linear reinforcing wires (as opposed to a coil) in the brake housing, of all things. I'm not sure if they recommend a ferrule where that housing meets the brifter, (They don't include enough in the "Racer" re-cable kit to do this) but I used metal ones there. I pulled apart an older bike a few years ago where the brake lever had started to do exactly what you describe the shifter doing, and I was sure I had really screwed up and used shift housing for my brakes. Now I'm pretty sure it was just the way the kit came and I hadn't used a decent ferrule.

cafiend said...

It's true: some in the bike world these days recommend using linear-wire housing "to make the brakes more responsive." Aieee!

Not all metal ferruels are created equal. We use Jagwire 5mm open ferrules. The ends are reinforced to take the pressure of linear wires. Cane Creek's basic metal ferrule fails rapidly when used on linear wires.

On spiral-wound casing the heavier ferrule isn't necessary, but we use it anyway because we don't want to bother with two very similar items. One good metal ferrule rules.

Matt Boulanger said...

"Aieee!" indeed. The brake housing that blew up on me was especially heartbreaking because I had just finished a beautiful diamond weave/cloth tape/shellac taping job that I had to cut apart. Probably 25 bucks worth of handlebar stuff. -

cafiend said...