Due to a shifting issue on a brand new bicycle, mentioned in a previous post, my LBS, which is in another city, has given me the OK to inspect and lubricate the cable to the rear dérailleur. However, in researching what lubricant to use, it seems there is a reason not to use every lubricant known to man. I need to pick something at a local hardware store. Any recommendations?

I occasionally use chain oil, but if your bike is new, it is unlikely that what ever problem you are having is related to a dry cable. You may wish to find a youtube video that may address your shifting problem. It's IMO more likely a cable that has stretched, which is normal for a new cable.

If it is cable stretch, that can easily be solved with the barrel adjusters, by turning them counter clockwise. Check out the youtube video's, such as adjusting your rear derailleur .

I generally get 4 years + on a set of cables. I only use Dura-Ace and after a change shifting is like a complete new drive train.

The few times I accidentally got lube into my cables (Lubing the shifting mechanism) the cables deteriorated rapidly.

The last time I changed Campy Record original cables, I used a Harley silicone lube made specifically for cables and the result failed. I changed the cables to Dura Ace.

Lube may help a week or so, then it is history. Take the bike back to the shop, for a new bike this should be their problem.

I'm familiar with how to adjust the cable for stretch. The problem is that when I adjust so that the bike will up-shift properly, it is reluctant to down-shift, and when I adjust it to down-shift properly, it is then reluctant to up-shift. That's a friction problem. I need to check the cable for snags, poorly cut ends, etc, but I thought a lubricant might help - perhaps a dry graphite lubricant?

+1 this

Agreed, but the LBS is a 50 mile round trip, and I want to learn. If it isn't easily solved, they will get it back, and they are supporting my efforts to fix it.

Stainless steel cables in lined housings shouldn't need any lube. Galvanized cables benefit from a light coat of something. Doesn't really matter what since pretty much everything will eventually gum up and need to be cleaned and re-lubed occasionally. I use a light coat of the same synthetic grease I use in bearings simply because it stays put and doesn't seem to wash off or dry out like light weight oils. Graphite won't give you any oxidation protection (which is what I'm mainly going for on the galvanized cables).

50 miles is a great bike ride. Ride the bike there, meet your better half for lunch and come back in the car. Or, it could be your first century effort.

On a more serious note, with sticky cables your shifting will always be an issue. It is more likely the cable running under your bar tape, than the short back section at the derailleur. IMHO any type of lube will make things worse longer term. A high quality cable set, will set you back around $35, making the upgrade worth your while.

https://www.excelsports.com/main.asp?...ajor=1&minor=9

Very funny! I haven't ridden much in years, and I'm 52. It takes me three days to recover from a 10 mile ride! The cables on this bike are routed internally, and that is probably part of the problem. I'm going to check the cable in question for obvious problems, and maybe try some graphite. It that doesn't work, I'm going to have to buy some type of low friction cable. Having to fight a shifting problem is not acceptable to me.

Per Shimano's RD-6700 Techdoc:

https://techdocs.shimano.com/media/te...9830702204.PDF

"Grease the inner cable and the inside of the outer casing before use to insure that they slide properly."

No spec for the "grease" to use.
I used Finish Line on the last several builds & overhauls, works fine as would any quality bearing grease.

A snaggle-toothed cut on the housing is likely. Remove de-burr, lube and proceed.
I purchased a pair of dedicated housing cutters, clean un-compressed housing cuts. A dremel works well to de-burr pre-cut housing. Go all the way to the brifters to make sure the run is correct, de-burred & lubed. A re-tape may well be in order.

I made sure that my CF Merckx did not route the shift cables internally ( and had a threaded BB ) before I bought it.
Style over substance is a mechanic's enemy.

-Bandera

https://www.amazon.com/Shimano-SIS-SP.../dp/B001GSSNCM

Less than 2 ozs. of grease for $26.99. Wow! I guess the Shimano name adds value to that.

+1 Before lube, in this situation, I'd completely remove the inners and inspect everything (including ferrules and housing insides) for any fault.

"Shifting issue on a brand new bicycle"

I seriously doubt you have a cable lubrication issue. If your objective is to learn, why don't you tell us what your derailleur was doing?

it is nice grease though, very light bodied but not runny. it also not sticky or tacky which is hard to find