Shifter/brake cable with a partial cover

[oilboy123]

What is the main reason that the cables are not fully covered with the plastic/metal cable cover. In other words the cable housing goes into a lug and just the cable comes out. It then goes to another lug and back thru the cable housing. All my shifter and one of my brake cables does this.

Is this to save weight? I am going to replace the cables on my old mtn bike at some point. I think I am going to replace the cables witha a full covering instead of with just a partial cover to keep more dirt out.

It won't look as pretty but less dirt will get into the cable.

Any thoughts on this?

 

[huffmuds9320]

Good question.

The cable housing goes to the stoppers so that it can form a smooth bend and route its way to the brakes and the derailers. The way the shifter and the brake controls are designed make it necessary to form a bend since the cables are going from perpendicular to parallel on the frame.

I've seen some bikes that route the cable housing through the frame and use a complete length of housing. Also bikes that run the whole length of housing usually use zip ties to hold it along the frame of the bike. The way I see it is if there is more housing, it might be more drag.

Hydraulic disc brakes will have the whole length of hose of course. The front brakes have a full length of housing.

My old 2001 Diamondback mountain bike I ride in all kinds of conditions and terrain. I never had a problem with poor shifting due to the housing. I would put some lube though the housing to keep it smooth. However bad routing (short, sharp bends) however I experienced problems.

These are just my opinion.

 

[moribundman]

Plastic (PTFE, nylon, PP etc) lined cables don't need any added lube. The lube will eventually (S.S. says so) gum up and cause increased friction.

If increased dirt and moisture ingress is to be expected due to a bike being ridden under adverse (sandy, muddy, rainy, humid, freezing) conditions, I would definitely go with much cable housing coverage as possible.

 

[NYEngineer]

All of my old bikes had cables exactly like you say. They always worked fine and I did remove the cables from the housings and clean and lube them from time to time.
My new bike has full length housings that go all the way to the derailers. They're Jagwires. Very smooth.

 

[moribundman]

I once owned an old 1950s touring bike. The cable housings were made from just spiral-wound steel without an inner liner. There were cable oilers on all sections of cable housing. That system worked pretty well, too.

 

[mpvue]

cable drag is/was the enemy. like mori said, years ago, there weren't any liners in the housing, so they would need to be oiled. on old road bikes, downtube shifters only needed one small piece of housing at the rear der; the front der didn't need any. no housing, no place for dirt to hide.
cheap dept store bikes would frequently use full length housings; trust me, it wasn't a better way. they felt like poop, impossible to lube the cable, high restriction.
slotted cable stops really show the advantage of exposed wires; put the rear der in low gear, then push the lever to high, releases tension, allows you to pull the wire out and lube it. put it back in, der satill in adjustment. AND, contrary to popular opinion, PTFE/teflon wires DO wear out, and if you don't want to replace them all the time, you will lube them.

 

[ilh]

Originally Posted By: lpcmidst128
The cable housing goes to the stoppers so that it can form a smooth bend and route its way to the brakes and the derailers. The way the shifter and the brake controls are designed make it necessary to form a bend since the cables are going from perpendicular to parallel on the frame.

I've seen some bikes that route the cable housing through the frame and use a complete length of housing. Also bikes that run the whole length of housing usually use zip ties to hold it along the frame of the bike. The way I see it is if there is more housing, it might be more drag.


this feller hit the nail on the head right there!

the exposed cable is for friction purposes. while you cant have an open cable because it would slop all over the place, housing a cable simply equals drag. thus, modern bikes use as little housing as they can, to minimize frictional losses. there's nothing worse then stiff cables to ruin your ride!

as for lubricating the housings? the cables that Shimano provides are already pre-greased with a thin grease for their derailleur cables. the Jagwires we use at my shop come dry. Sheldon Brown, the late guru of bicycles, advises to not lubricate them for the worry of them gumming up. I go by Sheldon's teachings like a bible (and I'll be the first to admit it. the man was brilliant!)

check his website if you have free time... some excellent lessons to be learned on that site. I have over, and over, and over again... and I'm a shop mechanic!

Hope that helps,
-Ian

 

[rpn453]

I think it's just done to save weight and cost, and to keep the cables from rusting solid. A full-length cable in lined housing can be just as smooth as exposed cables - the friction is in the bends, not the straight sections - but water can collect in low spots and cause rust. I've seen many bikes with full-length housing whose cables were totally seized up.

White Lightning works great for lubricating cables. I've never seen cables that work as good dry as cables that have been lubed with White Lightning, and that includes the teflon-lined cables. The lubrication can last for years and doesn't attract dirt. I'm sure there are other dry wax lubes that work well for that too.

A few people have grabbed my brake levers and squeezed them, and then continued to squeeze them for a while, amazed at how smooth they feel. These cables are probably 10 years old and I lube them about once a year.

My other piece of advice for smooth cables is to clip off the sharp edge of the housing after you cut it. You almost never get a clean cut when you cut a piece of housing.

 

[tom slick]

I'd think that the longer the housing the more it could compress when the cable in under tension. Less housing could make for less "spongy" feeling.

 

[oilboy123]

Been to Sheldon Browns site before....RIP.

I like the different ideas and responses. Gives me something to ponder. Thanks

 

[rpn453]

Originally Posted By: tom slick
I'd think that the longer the housing the more it could compress when the cable in under tension. Less housing could make for less "spongy" feeling.


That could be part of it, but most of the sponginess will occur in the bends, where the coils separate, and most of the flex with V-brakes occurs in the brake posts and seatstays, which can be extremely flexible with an aluminum frame. My BMX bikes have full-length cable housing and they feel as stiff or stiffer than any other bike with the same brakes.

 

[oilboy123]

I will probably go with full cable housings. Unless one of the guys at the bike shop reveals some revelation to me.