What is the best way to lubricate gear and brake cables in their tubular housings? Up until now, I've used CRC/WD-40 with an extension tube and attempted to squirt the lubricant into the tube housings. However, I suspect that this is fairly ineffective because 1. WD-40 is not a great lubricant (judging by the other Q+A on this site), and 2. the lubrication doesn't travel very far into the tubes.
So what is a good way of doing this?
I use chain lube since I also prefer the solvent+grease wet chain lubes. That's exactly what you want inside cable housings. Popping the quick releases on brakes or frame attachments on gear cables, then dribbling chain lube along the inner so it runs down into the outer works well on cables that are already installed and doesn't require re-adjusting anything afterwards.
Many outers are pre-greased these days, and the way to fake that if you get cheaper outers is a grease gun. A syringe will work at a pinch, but it needs to be a small one or the force needed to squirt grease into the tiny hole in the outer will be extremely high. Trying to manipulate grease into a cable outer any other way is frustrating and I find it ineffective (I have tried!)
Using oil kind of works, but I find I need to re-oil the cables way too often. Grease works better. Teflon coated cables work even better, and the combo of teflon cables and pre-greased outers (or plastic-lined outers) is amazing. But not worth the $80 a set unless you're running 10 speed gears or something expensive (I use a Rohloff, and that doesn't care about fine adjustment, only cable friction).
As many cable manufacturers recommend, modern cables+housings are designed to not be lubricated.
So, if you have modern cables, I'd probably avoid lubricating the cables period.
As stated, modern teflon line outer cables do not require lubrication. These cables are often designated as being 2P-class cables. 1P cables lack the liner. Not all cables carry such an indication, visual inspection will quickly show if a liner is present. A teflon liner is a thin, plastic layer inside the outer cable, often white or light blue. If you have older, or cheaper cables, without such a liner, lubrication is required. Teflon lined cables with inner cables that have corroded and are stuck should be replaced, due to damage to the inner cable and/or liner. In an emergency however, lubrication can help to unstick these cables.
Note that WD-40 is NOT a lubricant and should never be used for any type of serious lubrication. It does more harm than good. See also this related question. Buy a specific cable lubricant, which is designed for penetrating through the whole cable. If this is not available, any other light oil or grease will do.
Cable lubrication is much easier using a specific cable lubricator. Mount the lubricator with the large hole over the outer cable, the small hole over the inner cable. Tighten the screws (gently!), insert the lubrication spray can straw and insert small quantities of lubricant until it flows out the other end. In general, you would want to lubricate from top to bottom, in order to have gravity help distribute the lube. Not for the brake cables however, be very careful not to get any lubricant on your brake pads/disc/wheel rim or any other friction part. For brakes, always lubricate Bottom-Top, or completely detach the cable from the brake before lubricating.
I use Rock 'N' Roll Cable Magic cable lube created specifically for non-coated cables. http://www.rocklube.com/cable.htm
Without taking the cable all the way out of the housing, I'll shift to get as much slack as I can in the cable so I can get the housing out of the stops (my bike has slotted cable stops) and put in a few drops and move the housing back and forth to get the lube distributed.
As has already been pointed out, good quality modern cables come already lubricated. However, if you must, how about one of these Lube Tube End Ferrules from a well-known cable manufacturer
?
The packaging notes:
JAGWIRE Lube Tubes for 4.5mm or 5mm Outer Cable
Lube Tubes allows for quick application of oil directly onto the cable Special boots seals oil in the housing Lube greatly reduces friction for improved cable performance Replaces standard outer cable ferrules Simply pull back the rubber boot to reveal the lubricating pad
Easy lubrication for your gear or brake cables For 5mm brake or 4.5mm & 5mm gear outer cables 3 Lube tubes supplied in each pack
I have worked lube into "difficult" cables by unhooking one end, working a piece of "rubber" hose over the end (actually two pieces, a short piece of small diameter and a larger piece several inches long, one within the other). Put a small spiral hose clamp around this assembly.
Use a bike stand with a rotating head to get the cable end pointing up, then spray lube into hose. You can generally wait for gravity to the work the lube into the cable, but if the hose is long enough you can grab the end and squeeze the lube into the cable with your fingers.
(I should also note that, when confronted with a rusty cable, I will first give the cable a treatment with "oxalic acid" solution (available from paint stores as a type of "wood bleach"), trickling it into the cable the same way one would do the lube (but before any lube). This, to a degree, dissolves rust, will often free up a "frozen" cable, and makes "so-so" cables move much more smoothly. Of course, one should follow up with regular lube.)
Motorcyclists face the same problem and ask the same question. While discussion is often hot and opinions are divided, I advocate oiling, as advises a man, whom I trust, with years of servicing several drivig school motorcycles. Citation:
I lubricate the clutch cable in school motorcycles weekly, which prolongs the life and improves ride comfort. For the lubrication I bought device allowing use sprays containing eg. a silicone oil or stuff containing molybdenum disulphide. However, I've copied once in a mechanic sensational patent: I solder quite accurately cable section of 0.5 cm from the end on both sides. It's to avoid abrasion and come off. Note that the cable breaks usually at the barrel (I have not seen other cases) by the rotation of the barrel in the handle (at which it rubs.
There is special device available:
I would never bother 'lubricating' cables. They cost around $20 each.
I have them lubricated at the annual tune up. If they go bad I simply have the shop put new ones on.
My free time is too important and valuable to me to waste on such nonsense. I spend it in getting educated and working. Therefore I have the money and spend it to have other people doing such work for me.
What is left is that I can enjoy my bike, while others lube.
