SpedFast

What is the difference between 5mm brake cable housing and 5mm shifter cable housing and can I use them interchangeably? I have a large spool of 5mm brake cable housing in my parts bin, but recently ran out of 4mm shift cable housing doing charity work. Went to replace and noticed there are lots of ads for 5mm shift cable housing. Thanks

smd4

Brake cable housing is generally made of tightly coiled steel with a covering--like a spring. Shift cable--if it's made for indexing--is made of longitudinal steel wires that run the length of the housing.

Brake cable housing--because of its construction--can compress under loads--like when squeezing a brake lever. It's very strong, however. Shift cable--because of its construction--won't compress--which is great for index shifting--but isn't as strong as brake cable. But it doesn't need to be--moving a shift lever doesn't put nearly as much strain on a cable as squeezing a brake lever.

Compressionless brake housing is more like shift housing--but it's covered in Kevlar to resist any outward bursting pressure generated by squeezing the brake lever.

Unless the bike uses friction shifters, I wouldn't use standard brake housing for derailleurs.

Andrew R Stewart 

I'll add a couple of tidbits to the good explanation by smd4.

4mm and 5mm SIS casing is pretty much interchangeable WRT shifting aspects. But their end caps are rather different. 4MM SIS casing generally uses plastic end caps/ferules. 5mm casing nearly always uses a SIS spec metal end cap. These 5mm end caps frequently look just like common 5mm brake casing end caps but have an important difference. The bottom of the 5mm SIS end cap is reinforced/thicker/stronger than that of the brake casing end cap. This is to better resist the pressing forces the SIS casing strands place on the end cap base/bottom. If you use a 5mm brake casing end cap on a 5mm SIS casing the casing strands can poke through in time (usually after the customer has picked up their repair and results in a ruined ride).

The other aspect of plastic and metal SIS casing end caps is that the metal ones can produce a tick like sound as the bike is steered. The SIS casing strands grate against the metal base/bottom of the 5mm SIS end caps as the casing slightly rotates with the handle bars being swung about. Andy

cyccommute 

The only thing I would add is that 4mm metal ferrules are available and far superior to the crappy Shimano plastic ferrules.


You can also find them in garish colors if you like.

SpedFast

Thanks for the very informative responses. I never knew about the ferrule end caps and have been using whichever fit for years. Ignorance is bliss, right?

Aardwolf

On older bikes the original shift cable outer might be 5mm brake cable - SIS introduced the 4mm standard in about 1984.

The shifter cable frame stop on my 1982 Holdsworth takes a 5mm outer which confused me until I spotted the error.

Andrew R Stewart 

Perhaps, but the vast majority of new bikes sold early on in the indexed era were equipped with 5mm SIS casings for quite a few years. IIRC it was not until the 1990s before the 4mm SIS casing was OEM on the higher end bikes. Andy

Aardwolf

Fair point, I should have said SIS started 1984 and introduced the special shift cables.
My 1982 bike definitely used bowden cable for the shifters originally, and still does.