Frequently tightening front derailleur cable

OK, so on the third time of going to the LBC to get my front derailleur adjusted on my less than two-month old bike (it gets hard and/or impossible to get it onto the biggest front chainring), I asked how to adjust it myself.

The employee happily showed me while checking out all the adjustments, but after just another 30-40 miles, I need to adjust it again. (I'm talking about tightening the cable where it connects near the chainrings, not the bolt tightener). Is this normal?

Is there such a thing as a "bad" cable? Am I doing something wrong? Could it be a problem that I need to lay my bike down in my car to transport it (alway on the left side)?

"Shift early, shift often" is my motto, so I don't think it's a problem of not shifting often enough... and I try to avoid cross-chaining.

Any thoughts? I'm getting really tired of this, and can't imagine having to pull over every thirty to forty miles on any upcoming long ride to tighten this cable...

No, it is not normal for a cable to need retightening every 30-40 miles. What type of shift levers do you have? Integrated brake lever/shifters, downtube shifters, bar-ends? One thing that would definitely cause the problem you mention is if you have downtube shifters that are sliding down the downtube. You'd see scratched paint if this were the case. Barring that, it's hard to say but here are a couple of suggestions. Maybe you've just crimped your current cable too much by having to readjust it so often, and now it pulls through the derailleur clamp. I'd try a new cable and if possible wait for it to finish stretching before retightening. I'd also be careful on shifts to the large chainring to not jamb the hard lever to the limit (if you have friction shifters).

Similar to a clamp-on downtube shifter sliding down the tube, if there are cable stops on the bike which clamp around the tube (rather than being braze-on fittings), you could have the same type of sliding problem which would loosen cables. Look where the cables from the levers change from housing (the thick plastic stuff) to bare wire.

Quote:

---

Originally Posted by DebW

No, it is not normal for a cable to need retightening every 30-40 miles. What type of shift levers do you have? Integrated brake lever/shifters, downtube shifters, bar-ends? .... Maybe you've just crimped your current cable too much by having to readjust it so often, and now it pulls through the derailleur clamp. I'd try a new cable and if possible wait for it to finish stretching before retightening. I'd also be careful on shifts to the large chainring to not jamb the hard lever to the limit (if you have friction shifters).

---

Oops, sorry I didn't include it. I have integrated brake lever shifters. I sometimes think I'd be better off with old-fashioned shifters that don't "click" over into positions, though...

And you know, now that you mention it - the first few adjustments it looked like the part of the cable sticking out of the clamp was getting longer, but now I'm not sure after the last one. I'll bring that possibility up with the LBS if it needs to be adjusted quickly again...

Finally, I'm not being intentionally obtuse here, but: how do I wait for the cable to finish stretching before retightening? It seems to me that once it stretches to the point that I can't switch to the big chainring, it needs to be adjusted. Am I wrong?

Thanks for the ideas.

Quote:

---

Originally Posted by witeowl

Oops, sorry I didn't include it. I have integrated brake lever shifters.
Finally, I'm not being intentionally obtuse here, but: how do I wait for the cable to finish stretching before retightening? It seems to me that once it stretches to the point that I can't switch to the big chainring, it needs to be adjusted. Am I wrong?

---

If you had friction shifters, you could wait and just put up with a longer lever throw to get to the gear. With indexed gears, you can't wait unless there is an adjusting barrel in the system. If so, take up the slack with the adjusting barrel as long as possible before retightening the cable with the adjusting barrel at the bottom. But I'm guessing there is no adjusting barrel or your LBS would have told you to use it.

Cables do stretch - high quality ones stretch less. But after a month or two of riding, the stretch should be gone and you should no longer be dealing with that. But if you replace the cable you have to go through it again. Good idea to determine if the cable end is getting longer. If not, the cable must be slipping back through the derailleur cable anchor.

OK - it's been solved!

First, I did start with the barrel adjuster, but when I couldn't adjust it fully and went into the LBS the last time (before today), I was scolded for letting it get too far using the barrel adjusters. :(

Anyway, here's the situation: Ironhorse has been sending too-short cable housings. Typically, apparently, bike manufacturers send all the same length cable-housings, no matter the size of the bike. It seems that Ironhorse is now customizing their housings, but it turns out that they're too short.

So, when I make sharp turns (never) or turn the handlebars to fit the bike in my car (always), the too-short housing was thrashing the cable. The guy at the LBC thought he was going crazy with being unable to adjust the cable properly until he happened to notice the cable housings and exclaimed "they put the bike together wrong!" (Again, though, it turns out it wasn't put together wrong, but outfitted poorly from the manufacturer.)

They fixed it today and replaced the cables and housings free of charge.

Yay!

(It was cute, though. The mechanic must have sensed how neurotic this all was making me, because - after he replaced the cables - he made a point of explaining that the cable would now need to be stretched for a while, so I should expect to have to bring it back in to be adjusted. I guess he was afraid that I would come in next time in tears. :o )

Thanks again for the help!

Glad to hear a happy ending to your saga. Odd though it is.