I bought a project bike tonight, just a late '90s Specialized Hard Rock. I didn't notice until I got home that it was missing the plastic cable guide for the derailleur cables. The bolt hole is there but the guide is missing.

What in the world is that piece called and are they specific to specific bikes or can I just grab one off of any similar bike and use it.

Are they something that most LBS would have?

I need one too. There are a number of them on Ebay, but I'm inclined to let the LBS check it out and supply the right one if they have it.
Most of the guides are similar, but the main differences are the holes for the bolts and the cables' separation width.

If it's a Shimano gruppo, sometimes the part# is on their tech sheets.

why would the component manufacturer matter? the type of cable guide (i think it's
called a cable guide) needed would depend on the frame and where the cable bosses
are located.

An LBS might just give you one and call it good.

Here is an online source to buy from:

https://www.universalcycles.com/shopp...s.php?id=24009

There is a Shimano model as well:

https://www.universalcycles.com/shopp...ls.php?id=6695

The Shimano model comes with an annoying protrusion not shown in the photo that makes it useless. The Campy model is actually the one that I have used successfully.

https://www.loosescrews.com/index.cgi...d=514133418305

If you need one for a new bike with an oversize BB shell i would try to get the campagnolo one.

One of those plastic guides accompanies every Shimano brifter kit. your LBS should have a bunch of leftovers there for the asking.

Well i went ahead and threw the frame into my car. Tonight on my way home from work, I will stop at my favorite LBS and buy both the cable guide and the proper BB removal tool (need the splined one).

I suppose in a pinch, I could rig something up using some cable housing until I get one if I have to resort to ordering one.

I was just stating a fact!
Deal with it!!!

Forgot to post. Went to my favorite LBS and he just tossed me a brand new one. Shimano just for the record.

Works great.

That "annoying protrusion" can come in real handy on some frames that require it. Usually low end frames, but when you need it you need it. For those not sure what I'm talking about, there is an expander plug on the Shimano mentioned that will fit larger holes in BB shells. Sometimes the plastic guide is riveted on and interferes with cartridge BBs. Removing the rivet leaves a hole larger than an M5 thread. I just put one on a bike yesterday or so. Had to sand down the protrusion a little for the cartridge BB. Used a shorter screw as well. I was thinking the alternative was to put a copper round the same size as the id of the BB shell and mig weld the hole up. I did not want to do that on the low end bike I was working on for multiple reasons. Luckily I found a guide with an expander plug in the parts bin. Now I know that Shimano makes one I'll need one for another bike. One could always cut off the protrusion, and drill out the hole if needed.

I split the cable guide thingy on my bike (Van Nicholas Amazon) and had to get a replacement from the LBS. I duly cut off and drilled the annoying protrusion, but having used it for a while I realise it's too chunky for my gear cables and has split the inner plastic cable housing and the cable guides on 3 month old flying snake cables (they come with special plastic guides that go under the BB). I've filed it down to get a better approach angle and am now looking for a new one. Just thought I'd share this to contribute to the body of knowlege about this piece of plastic - it's worth checking there's a nice taper on it and it's not a big cheap lump of plastic like the one I got!