What happens if you don't use cable outers?

[summerdays]

I started to change my brake cable, thought I had all the bits, so removed all the old stuff, and then realised I didn't have the bits that go at the end of the brake outer casing. I had to quickly replace all the old stuff though it was a right pain passing the old bent cable through the old outers.

I wondered what would have happened if I temporarily skipped the outer sections and just redid the brake cable? I didn't, but I would like to understand how the outer helps the cable perform.

 

[Spinney]

Apart from bits where the cables run straight, the outer acts like a kind of pulley. Without the outer keeping the wire curved, it would just pull tight between the guides, too much would need to be pulled through (and it would be much harder to pull) and your brakes wouldn't work.

 

[summerdays]

Thank you! I was tempted to try but I didn't have enough time before I wanted to ride it! Still might do a quick experiment to see it in practice when I take it all off again to do it when I've got the parts.

 

[Scoosh]

Still might do a quick experiment to see it in practice when I take it all off again to do it when I've got the parts.

On the flat, with plenty of room might be a good idea ...

 

[summerdays]

Test as in in the garden, not necessarily riding it

I learn visually or by doing so it will be interesting to try it to see it in action.

 

[Mile195]

If you mean you didn't have the small plastic ferrules that go on the ends of the brake cable outers, you could probably have got away without them for a few days until you got some more. The end of the cable outer will probably sit ok in the moutings that each piece terminates in without them, although the ferrule offers more support and prevents contaminants getting into the cable outer which would otherwise increase the effort needed to brake and corrode the inner cable.

But yes, in answer to your question, your brakes will not work without outers. Imagine putting a piece of string through a hospipe bent into a semi circle on a table and tying, let's say a coffee cup, to one end. If you pull the other end, the cup would move toward the end of the hose. However, if the hose wasn't there, and it was just a piece of string lying in a semi circle on the table, the semi circle would just deform if you pulled the end without the coffee cup attached to it.

 

[summerdays]

Yes ferrules on order! Just wish I'd thought about it when I was in the bike shop this week.

I couldn't even use the old ones, as they seemed to have been clamped onto the outer.

 

[summerdays]

does the gear cable outer do the same thing, since the wire in it goes a different direction so I assume has a slightly different role?

 

[Spinney]

Both outers do the same thing, both cables do the same thing (i.e. pull - that's all the cable does, the difference is in what they pull on).

 

[summerdays]

Both outers do the same thing, both cables do the same thing (i.e. pull - that's all the cable does, the difference is in what they pull on).

But the outer IS different... And isn't it that you can use a brake one for a gear but not the other way around? Because the brake needs to be stronger?

 

[Spinney]

Well one might need to be longer, or stronger, or have different fittings at the ends, but from the mechanics point of view the cables both just pull, and the outers both just give their cables something to pull against. The outers may be different thicknesses if the cables are different thicknesses, and different lengths depending on the routings, and on any adjustment widgets fitted.

By the way, when you twiddle a little thingy to make fine adjustments to the brakes or gears, all you are doing is making the outer a little longer or shorter.

 

[summerdays]

Well one might need to be longer, or stronger, or have different fittings at the ends, but from the mechanics point of view the cables both just pull, and the outers both just give their cables something to pull against. The outers may be different thicknesses if the cables are different thicknesses, and different lengths depending on the routings, and on any adjustment widgets fitted.

By the way, when you twiddle a little thingy to make fine adjustments to the brakes or gears, all you are doing is making the outer a little longer or shorter.

Yes my brain has worked that one out... Though it did take a few years to reach that conclusion, and now I find it much easier adjusting brakes. I was fairly impressed that I managed to take the old stuff off, start trying the new stuff and then search all my bits boxes in the hope of finding spare ferrules, and then forcibly put it all back on again in under 15 mins, I couldn't have done that years ago. (Though I still lay all the old bits out in order when removing it to help with working out the order and size of the bits).

 

[Spinney]

Yes my brain has worked that one out... Though it did take a few years to reach that conclusion, and now I find it much easier adjusting brakes. I was fairly impressed that I managed to take the old stuff off, start trying the new stuff and then search all my bits boxes in the hope of finding spare ferrules, and then forcibly put it all back on again in under 15 mins, I couldn't have done that years ago. (Though I still lay all the old bits out in order when removing it to help with working out the order and size of the bits).

15 minutes is impressive!
Mr Spinney is quite happy messing about with bikes, and I'm afraid I'm lazy enough to let him do it! The only thing I do practice is changing tubes, in case it happens when I'm on my own, but if I get a puncture when we're cycling together he always takes over on the grounds that it is much quicker!

 

[Mile195]

does the gear cable outer do the same thing, since the wire in it goes a different direction so I assume has a slightly different role?

Any cable with an inner and outer does the same thing. Why don't they just sell one kind of cable for bikes then? Well there are differences between brake and gear cables in their construction even though they do the same thing. Gear cables have to be manufactured in such a way that there is minimal "give" in them. A steel cable under tension will stretch a little. For indexed gears, a cable that stretches too much as force is applied will cause inconsistencies in shifting. At one end of the gear range it could work well, but at the other each "click" on the lever would equate to a smaller and smaller movement at the deralleur as some of the movement goes into stretching the cable, rather than moving the derailleur. The outers are also made differently. You'll see if you cut a gear cable outer and a brake cable outer that they are different underneath the plastic coating.

 

[summerdays]

So in summary....
Gear cables really no stretch, so precise pull
Brake cables slight stretch but stronger?