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My front derailleur cable has snapped within three months of changing. As a result I’m seeking advice on good biking practice.

I ride a Specialized Hardrock Disc SE 26 from 2014. I ride on a college campus and go off road (albeit quite elementary of a “trail”) often. There are a lot of hills and I’ve noticed that almost none of the other riders touch their shifters.

I on the other hand, treat my bike like a car, and shift constantly. I start with (1,4) front and back, and go through the 21 speeds, while skipping some.

This might seem silly, but do I have the whole concept of bike riding wrong? Am I shifting too much, causing accelerated wear and tear, because a bike’s gears aren’t meant to be shifting constantly? As noted above, I don’t see some other riders touch their shifters at all.

Kindly give me your thoughts on the matter

I appreciate your help!

Matt

[EDIT]. I was riding thru the woods when a twig got stuck in my drivetrain. The gears were thrown out of whack and my chain broke. I took it to get fixed and it ran fine. Then I noticed that the front derailleur cable was slack. It wasn’t taut as it used to be. It shifted well though, and I ignored it. Then today I shifted into gear 3 on the front and didn’t feel the resistance when pedaling. I glanced down and sure enough, cable was sticking out and the chain had not moved. The cable had snapped.

[EDIT] The Cable broke at the derailleur end, right where it was anchored to a point on the derailleur mechanism in the front. As user ojs suggested, it is indeed a pull-up type of shifter. I shall add more pictures.

[EDIT] I appreciate your patience with me, this is my first post. I've uploaded three images which I believe aid in our investigation. Attached is the link to specialized bicycles. The page is the manufacturer's specifications of the Hardrock.

Specialized Hardrock Disc SE Specifications

Cable Tie used to route cable is missing

Shimano Tourney

Front derailleur snapped cable

  • Without front derailleur, the cable certainly won't snap if you are willing to invest into 1x setup to go onto a budget bike. – Klaster_1 Dec 8 '18 at 5:16
  • How far have you ridden in that time? I'm surprised it's the front that keeps failing, but on one of my bikes the back derailleur cable lasts about 5000km. Are there any sharp bends in the cable? Does it feel stiff? Did you replace just the inner last time, or the outer as well? – Chris H Dec 8 '18 at 6:14
  • Chris H There are no sharp bends in the cable. My back derailleur has never given me any problems. Haven’t replaced in since purchase, about 4 yrs ago. – Matt Dec 8 '18 at 6:43
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    Where does the cable break? Constantly breaking cables usually mean there is a sharp edge that wears through the cable, but the question body mentions breaking cable only once. – ojs Dec 8 '18 at 9:15
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    Just to clarify, your title says you "keep breaking" cables but you only describe two incidents. If it was just two, it's entirely possible that the first one was because the cable was old and worn (every cable will break eventually) and you were unlucky with the second one. – David Richerby Dec 9 '18 at 16:21
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Excessive force or frequency in front shifting habits may be able to play a role in a cable breaking, but it's very likely that it was primarily caused by factors beyond your control.

Front derailleurs vary in how much bending in the cable at the anchor bolt is created as they move through their range of motion. Some recent mountain front derailleurs push this to extremes, which is unfortunate because in doing so they add to the risk of breaking cables.

Mechanics are at times faced with a decision in setting up cables whether to accept there being a previously anchored section between the final anchor point and the lever, or of clamping partway over a previously anchored spot. This can happen as a result of anchoring the cable and then the derailleur's mounting position needing adjustment or by needing to have less starting tension or a more inbound low limit screw adjustment. The problem with allowing this is that it creates some degree of a weak point, and whether it's enough to lead to breakage is impossible to say conclusively. Typically the more skilled a mechanic is, the better they are at sticking to an order of operations that negates this, while newer mechanics may not even realize it's something they should care about.

At some point, the scrupulous decision becomes to put a new cable in and start over, but it doesn't always happen when it should. When cables break at the anchor bolt, I think this is the most common primary reason.

As for shifting habits, most people on multiple-chainringed modern bikes (as opposed to 10 or 12-speeds, say) stick to choosing a chainring that matches the current terrain and then adjusting their rear gear as needed. So in other words you're shifting in back far more frequently than in front. Because the jumps between gears in back on modern bikes are relatively small, not much is lost with this approach in terms of pedaling efficiency, and the inefficiency and hassle of doing all that front shifting is saved. Older bike drivetrains with smaller numbers of gears in back and larger jumps pushed one more in the direction of making constant front shifts in order to find a reasonable gear to be in.

There are stylistic and strategic elements to shifting too. Some people just like using muscle to get through spots where a lower gear could also be appropriate, or conversely might choose to force themselves to operate at a higher cadence when a higher gear would also work. From an efficiency standpoint, these things have to be weighed against the lost efficiency of bothering to shift, especially in front.

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Regarding shifting practices: Most mountain bikes have much larger gear range than what is useful for normal riding. The extreme low end is there for climbing extremely steep hills and marketing. In normal riding on flat ground a normal person should be able to start from full stop and up to decent speed without shifting, and the extremes of the gear range are usually reserved for climbing and descending.

Shifting should not break cables, though. You probably have some kind of mechanical problem or very poor quality cables, but it is difficult to tell from the information that you give.

  • The cable might be excessively stressed when passing under the bottom bracket where usually grime builds up. Lube mixed with grit does exactly the opposite of what it should do and the amount of force needed to move the derailleur exceeds the strength of the cable. Get higher quality cables and check/clean that spot more often. (Also check the derailleur for lightness of movement.) – Carel Dec 8 '18 at 16:58
  • @Carel did you look up the OP's bike? I just did and it has the front derailleur cable routed from top. Also, please do not answer in comments. – ojs Dec 8 '18 at 19:03
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Answer after pics added.

Looking at the second pic, looks like your derailleur cage took a hit to the outside plate and is bent inwards - presumably from the stick the drivetrain ingested. That's going to potentially mess up downshifting.

You could think about a replacement derailleur. That would hopefully also solve the problem of the cable snapping at the derailleur attachment point. Evidently the cable is being stressed at that point.

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