lubrication of bottom bracket cable guides
 

I have an old MTB that has three cables running under the bottom bracket, both deraillers and a chainstay mounted u-brake. It seems hopeless to keep this area clean to begin with, and lube just attracts dirt all the worse. How should I service this? On my road bike I never had issues just putting a light oil where the cables rub on the guide. But on this MTB I road 12 miles of dusty trail today and the clean and lubed area I started with looks like a cinamon glazed donut.

Thanks

Dry lube or wax?

I noticed that the shifting was becoming more sluggish on my Schwinn SS. I found that by running the shifter cables through a couple of pieces of PTFE tubing under the bottom-bracket, helped enormously to reduce the friction, and improve the shifting; I'll see if I can dig out the pics I took at the time.

- Wil

I don't use any lubricant on bottom bracket cable guides. I just keep it clean and have never had any problems that I could attribute to that.

I've always deliberately ignored these guides and nothing has ever gone wrong with them. My present one on my road bike is plastic and easily replaced. Never had one on my mountain bike.

Al

This is from Sheldon Brown's glossary:

I ignored these as well until I bumped in that quote, so when I cleaned up my road bike I put a few drops of 3 in 1 oil where the cables rubbed the guide and everything has been fine. Not a great idea with the mountain bike under dusty circumstances.

I ride a lot on crushed limestone trails, and have had this problem. There is no way to keep the dirt out, and after a while friction builds up and interferes with proper RD shifting.

On my previous bike, I cleaned and lubed the guide regularly with Tri-Flow and a toothbrush, which worked OK but was a bit of a hassle. This past winter, when I built up a new Cross-Check, I ran the cables through 6" lengths of housing liner where they run through the guide. 300 miles so far without a problem, but we'll see how it works over the long haul.

These open cables under bottom bracket represent truly bad design. The cables would normally always break there and, in addition, interfere with attempts to mount a kickstand.

Myself, I went through the following stages with my primary bike: 1) moved the cables under BB into housing, 2) moved the cables over the top tube, employing clamp-on stops and changing the front derailleur, 3) got braze-ons done for the top-tube routing. Now I live happily ever after. However, also whenever I run into a situation where an open-air cable represents a problem of some sort, I just put it into a housing.

Clean and dry the area thoroughly. Either don't use any lube or use a dry wax-type or, better yet, graphite in an evaporative carrier such as Lock-Ease. It will lube the cables but has no tendency to attract dirt.

That area tends to get sticky if you use sugary liquids in your water bottle. I occassionally have to throughly clean that area and apply dry lube.

This is a very good idea.

Alternatively, you could do what I do: instead of light lubes like 3-in-1, pack the whole thing with axle grease (i use a high-pressure molybdenum grease) -- the dirt will stick to the outside, but it won't get where it can gum the cables up. They'll just create their own little channels in the lube and slide back an forth inside it. Occasionally you'll have to clean and relube, but that's the case with anything.

I was waiting for somebody to bring that up.

The fact is that I do virtually no maintenance on my under the bottom bracket cable guides and I've never, ever had any autoshifting or other problems that I could attrubute to the cable guide. I live 2 miles from Missouri's Katy trail so I do a good amount of riding on crushed limestone. It's still not an issue for me.

The OP, on the other hand, says that he carefully cleans and lubes his cable guide and that it's a mess.

A kickstand T_T

My front shifter was becoming slow on return, occasionally it would stick. After reading this thread, I put a little Boeshield T9 in the cable channels. My shifters work better than new!
Mud:D

RG, since you seem to bike under the same conditions as I do without problems, I'm all ears, and I'm all for minimizing maintenance. I tried ignoring the guide and experienced problems, which led me to clean/lube with Tri-Flow and a toothbrush. That works, but requires regular repetition.

Maybe using a combination cleaner/lube was my downfall. In a previous post, you said you "just keep it clean." How do you clean this area?

I don't do very much. Since you seem to be attracting a lot of dust, I think that I'd clean the cable guide area with mineral spirits to get rid of all the old lube. Then I'd just run the cables dry. It works for me but YMMV.

Thanks. If running housing liners down there doesn't work out, I'll give it a try.

A very light application of bee's wax (sold as a lubricant for wood screws) on the cable portion that runs in the bb tracks works well. Once a month I also clean the tracks with a tooth brush.

I agree the exposed design is a poor design. The problem of ignoring the cleaning is that the performance of the cable is gradually diminished, and you don't notice it. I learned this the hard way, when I broke a shifter lever because I needed to apply more force. Clearly, the shifter should not have broken - it wasn't that much force- but I don't think the added force helped.

After fixing the shifter, cleaning the tracks and lubing with a small amount of bees wax the shifting is soooo much better.

Installing a piece of housing is not a good solution because I see the housing filling up with dirt. But I've never tried it, so I can't say for certain.

In any case, the bottom bracket tracks should be on everyone's preventative maintenance routine.

Here's a picture of the BB guides on my Schwinn SS:

- Wil

Wil Davis

What tubing is that in the pic, and where did you get it? You said it was PTFE, what is that used for? I was concerned that no tubing would be small enough to pass through the cable guide, but that stuff would. This bike is 20 years old and it also has a u-brake cable running through it so I would need it sized for brake and shifter cables. Did you do anything to stop the tubing from moving around when the cable moves?

I picked it up at my LBS and they seemed to know exactly what I meant when I asked for some PTFE tubing for the shifter cables. It's just pushed into the guides, and relies on friction to keep it in place; it seems to have worked OK on my Schwinn for the past couple of seasons.

Hint: If you have difficulty in finding the tubing, you could always look around for some electrical wire with PTFE (Teflon) insulation, and remove 3 or 4 inches for your needs.

Good Luck!

- Wil

PS: PTFE

I don't know if it's PTFE, but I just cut open some lengths of housing and used the liners from those. Only problem so far is that they tend to slide a little in the guides; I'll probably put a dab of silicone under one spot to hold them in place.

Shimano sells small rolls of that tubing intended as liner for brake cables. It's about $2 for 6 feet or so and your LBS either has it or can order it.