TallRider

I'd never thought too much about cable housing - just make sure that I have shifter-cable housing when running indexed shifters.
But I'd noticed that the shifter on my flat-bar commuter bike isn't working great. (7-speed rapidfire unit for rear derailer, no front derailer as I'm running a single chainring) I usually would have to over-shift (push the rapidfire lever beyond the indexed click) to shift into a larger cog. And I would have to push somewhat hard, to the point that after longer commuting rides, my right thumb was sometimes sore at the fleshy point that pushes into the rapidfire lever.

I thought the cases were:
a) old chain that may be more side-to-side flexible and thus shifts less crisply - chain isn't "stretched" too far though
b) rapidfire mechanism gummed up over time on a bike that lives outside, albeit under a shelter when it rains
c) shifter cable was noticeably less smooth exterior than some shifter cables

I asked a bike shop about buying new shifter cables, and the conversation with the mechanic convinced me to try new cable housing first. According to the mechanic (and this is totally plausible, I'd just never considered it) old housing gets gunk built up in it that impedes the movement of a cable. Cables get gunked up too but it's easy enough to clean them off with a solvent-dipped rag.

So I installed a new shifter cable housing, just between the chainstay and rear derailer. Shifted fine on the bike stand.

And when I biked to work this morning, when I first made a shift, I accidentally punched through three cogs! The cable friction was so much lower, and apparently the strong pressure that had been required to depress the shifter (only for shifts from smaller to larger cogs), was entirely a result of friction within that section of cable housing.

For the record, the original cable housing between chainstay and rear derailer was also too short, and my replacement is about an inch longer so the curve is less sharp.

bikeman715

yes new housing is a wonderful thing. I replace my every year or more often when needed due to the weather here.

Panthers007

Folks should always oil the cables and drip oil inside the housing, too. Don't use grease - it can gum-up the works.

New cable-housing can/does change the whole look of a bicycle. Choose your colors with this in mind.

bikinfool

Yes, it can be amazing what a little fresh housing can do. On several of my mountain bikes I use a full run of housing, which keeps the crud out much longer, too.

Cannondaler

I've always said that a new cable deserves new housing. I always change the cable and housing at the same time as a rule, especially with the derailleur cables.. Not always necessary but it doesn't cost much more to do them both.

Basil Moss

I'd been advised not to do this, since it attracts dust, and eventually gums it all up much worse. My understanding was that this used to be necessary with old style housings, since the cable was rubbing against the coil of the housing. However, newer housings have a plasticy liner, so metal-metal friction is eliminated. So there is no need to lubricate and a longer life expectancy for cable and housing.

mloywhite

I just changed my housings and cables Monday, on my 2 year old Orbea. I could not believe the difference it made in how much pressure is needed to shift gears on the rear. I used a Jagwire Racer complete set, it came with everything, for about $30.

Al1943

Both Shimano and Campagnolo recommend lubricating all cables, but don't specify type of lube. I use automotive silicone door lock grease.
Sometimes lubricating the cable where it runs through the short housing just before the rear derailleur can make a significant improvement in shifting performance. Detaching the cable and sliding the housing forward will expose the cable for lubrication. Don't do this if you're not willing to adjust the cable.

Al

Panthers007

I like Tri-Flow Teflon liquid. It lasts a good, long time, and it penetrates the cable. I've never had a problem with it attracting dirt inside the housing.

TallRider

the mechanic I'd talked to specifically mentioned tri-flow, because of its status as a "dry" lubricant.

Cannondaler

Shimano cable sets come pre-lubed, the housings have a light lithium or teflon grease in them. I usually don't lube new cables but I will lube them after they have been on the bike a while especially if I have ridden in the rain. I use Tri-Flo or Prolink Gold. Teflon coated cable sets or Gore-tex sets should not be lubed, the lube can cause the teflon to degrade and gum up inside the housing. Shimano housings have a teflon liner but it is thicker than the teflon coatings that some cables have so it is ok to lube Shimano sets.

Panthers007

It's not the Teflon that degrades. Teflon is, for all intents and purposes, chemically inert. That's why we use it in organic chemistry labs for applications where it will be exposed to amazingly corrosive materials.

bikinfool

The whether to lube the cables or not argument somewhat reminds me of the old arguments as to whether to grease a square taper spindle or not. I've heard it both ways from good mechanics, and have success with clean dry cables as well as lubed (tri-flow if I do) cables; have had success using stainless or teflon coated ones, too.

interested

Shimano uses silicone grease in their Teflon lined, standard SP-41 dérailleur housing. Silicone grease displaces water and works well below freezing and apparently doesn't gum up so easy.

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Regards