hazben1

I have a small 6" tube which runs through the BB for the FD shift cable. I need to replace it. I have been to a few LBS and can't find a tube small enough. The tube needs to be a tiny bit smaller than what they stock. I have a few pieces which are just a tiny bit too big. Would it be a totally bad idea to drill the entrance and exit hole with a drill bit which is 1/32 larger than the Hole? Also what is the best way to remove the little plastic piece screwed to the underside of the BB which the shift cables ride on. The Phillips head is striped out and I currently have it soaking in PB Blaster.

Andrew R Stewart 

What is the frame material? For metal frames a slight over sizing of a small hole is usually quite OK. For carbon much less so.

One factor with these cable guide tubes/sleeves is the long term wear they can see. Some OEM guide tubes are made of a quite wear resistant material where as many of the off the shelf tubes/sleeve are much more flexible and softer. So get a bunch of extra for the future.

As to the under BB cable guide removal, first try to source a replacement guide to use if the OEM one gets messed up. Can you use needle nose pliers or small vice grips to grip the screw head with? You could try to drill and easy out the screw but I'd save this method for the last resort. Next would be to cut away the guide, leaving the screw head standing proud of the shell and then an easy thing to grab with a vice grip.

For reassembly use a stainless cap bolt and anti seize compound. Andy.

FBinNY 

I'm confused. Generally the FD cable is routed UNDER the BB shell, not through it. The fact that you have a screwed on guide seems to reinforce that this is the case for your bike. So what tube are you talking about, and where does it run?

A photo may help.

hazben1

Thanks for the quick reply. The frame material is carbon but I suspect both ends of the hole which the tube travels through is slightly smaller than the overall diameter of the whole.

The only tubing I could come up with locally is the black tubing which comes in a roll.

As far as the cable guide removal I do have a replacement so I could tear up the old one if need be. I am also thinking of buying one of those bits which you can use to remove stripped Phillips head screws.

hazben1

Sorry I can't post a photo but yes the cable is routed under the BB. Attached to the BB is a plastic plate/guide which the shift cables for both FD and RD rides on. From this plate there is a small tube about the size of what you get with WD40 which goes though the BB and then angles up towards the FD. The small tubing acts as a guide or housing while it runs thru the BB.

Miele Man

You have a bottom bracket cable guide and a tube through the bottom bracket? Seems to me you'd use one or the other. An image would be a great help.

Cheers from Miele Man

FBinNY 

OK, I get it now. The tube doesn't run through the BB. It runs through the web section which encompases the area behind the BB and what would be the chainstay bridge on a steel bike.

The purpose of this is simply to prevent the wire from chafing or scoring the entry at the hole, and sawing the frame apart over 10,000 years. Go to a hobby shop that sells gasoline powered model airplanes and shop for fuel line tubing. Or source Teflon, HSPE, or PVC tubing there.

You can also use electrical "spaghetti" or similar, but I find it to be soft and cause excess friction.

BTW- since it's a carbon frame, I'd save enlarging the hole as an absolute last resort, and would likely run the wire bare before doing so.

hueyhoolihan

i find it hard to believe that your LBS doesn't have that kind of thing. my new frame came pre-threaded (for internal electronic shifting i suspect) with about three feet of that stuff for what i believe was to be used for derailler and brake cables or wiring. ya, it's about the diameter of the WD red plastic tube, but mine is/was translucent and much more flexible, they've been using it for years (or something similar) under the BB to protect the frame from cable wear, as noted in a previous post.

tomacropod

Just take the tube out of a v-brake noodle.

- joel

Reynolds 

You can use the lining from a shift cable housing. Cut the plastic cover lengthwise and the longitudinal metal strands will come apart, leaving the inner tube free.

hazben1

Love this idea. Will get back with you'll later in the week to let you know how it goes. Thanks a lot for all the guidance.

hazben1

Update. I tried to get the inner lining out of a offcut piece from my 105 set. However getting the metal case from around the lining was super tough. I then found an old Jagwire cable housing which has the individual wires. The inner tube came out super easy and was the perfect size to go through the BB. Bike is back together and am ready to hammer 1st thing in the morning. Thanks again for all the help.