or stainless. An inner core is created using seven strands with an additional twelve
wrapped around the outside in a slight spiral.Shift housing features four layers. From the inner-most layers out, they include:
• a polymer inner liner, which may or may not be lubricated
• a shell made of linear steel strands
• another polymer layer that stabilizes the linear shell
• and an outer layer of housing that faces the elements
housing has a shell of coiled, flat wound wire wrapped around the inner liner. This
wound wire flexes slightly to resist the significantly higher load that brake cables put
on housing. This flexing would wreak havoc on shifting performance because it
doesn’t deliver the precision movement needed for clean shifts.Shift housing resists this flexing by using linear strands of wire that run the length
of the housing parallel to the shift cable. These wires experience much lighter
loads, but are designed to keep the housing from compressing, resulting in clean,
crisp shifting. If you’ve ever tried to use shift housing in place of brake housing you’ve
seen what a poor substitute it is. The force of braking will either cause the linear
strands of wire to compress and bow out or simply split the housing into pieces.
All this, not to mention the cables and housings for each application are of vastly
different size, are reasons to never switch up the two.
We’ve all seen cables rust, but could this cause them to fail?
How is the cable “head” attached to the cable, and why is it the shape it is?
Mountain bike brake cables have settled on something fairly standard, whereas road
components have a couple different types of cable heads for both shift and brake.The attachment of the cable head is accomplished by first cutting the cable, then spot
welding the end. Once complete, the welded end is “punched,” causing the individual
strands of the cable to mushroom out. This mushrooming allows the cable head to be
forged around and through the strands making it extremely strong and resistant to being
pulled off the cable during braking or shifting.
to do with housing compression that occurs after installing new cables.If you’ve ever put on new brake cables and housing you know the way to finish everything
off is to give the lever several hard squeezes. This compresses the flat-wound wire and
“stretches” the housing. There’s a noticeable change in lever feel once this has been done.
It’s less of an issue with derailleur cables and housing, but it’s still good practice to get any
settling that the cables and housing are going to do out of the way before you send a new
bike out on its maiden voyage. This can be difficult if the bike uses internal cable routing. But
again, it’s usually not as dramatic on shift cables, and if it does occur all it takes is a simple
twist of a barrel adjuster to take up the slack.
Ride better through knowledge….
Bike Mechanic / Fleet Manager
0800 444 144 / 09 257 4673