Cable outers curiosity

[lutonloony]

apologies if this is on the wrong forum, maybe I should be in the cafe. Replaced brake and gear cables at the weekend (how the other half live). I noticed that one of the outers was like the old "net curtain wire" ie spiral wound, but the other was more twisted wire if that makes sense. Just wondering why the two different types.

 

[Yellow Saddle]

Brake cable outers are made from a steel ribbon wound into a tight, compression-less spiral. Gear cable outers are made from helical-wound steel wire.

Brake cable outers can make tighter corners than gear cable outers. Gear cable outers will burst open if a high-tension cable is pulled through it, whereas a brake outer won't burst.

The helical version forces large radius corners to keep friction to a minimum, a crucial element for good shifting.

 

[lutonloony]

Thanks

 

[Ihatehills]

On this subject, what are peoples opinions on ptfe coated cables? I'm due to change my gear cables soon and wondered if that was the way to go.

 

[Tim Hall]

On this subject, what are peoples opinions on ptfe coated cables? I'm due to change my gear cables soon and wondered if that was the way to go.

My experience of them some years ago was that the PTFE coating eventually came unstuck (not surprising, it is meant to be slippery stuff) from the cable and clogged up the outer with predictable results. This was on a drag brake cable on a tandem.

 

[Yellow Saddle]

My experience of them some years ago was that the PTFE coating eventually came unstuck (not surprising, it is meant to be slippery stuff) from the cable and clogged up the outer with predictable results. This was on a drag brake cable on a tandem.

I think that's everyone's experience if they are honest and not trying to rationalize the premium they paid for that defective product.