Been carrying a spare cable for decades now. Why? I've never seen or heard of a cable breaking. I can hardly tin snip thru one. Wasted baggage that I will never use?

My hypothesis: The reason you've never needed one is because you've always carried one. The next time out you don't have it, you'll need it. So sayeth Mr. Murphy

I've broken RD cables, never a FD or brake. So I always carry a RD cable. Quite small, quite light, really. I'd hate to try loaded touring on a 2 or 3 speed bike, though that's fine on a sport bike.

The cable broke in half? or did the little crimp piece on the end fall off? or something else? I can't imagine an airplane grade metal cable breaking.

On my 10-speed Campagnolo shifters, the cable makes a 90 degree turn within the shifter body before it reaches the cable housing. That repeated flexing eventually breaks the cable, strand by strand, until the last few go all at once.

And it can be quite difficult to fish out the frayed stub and crimp, since there's very little of the cable sticking out. I used a bunch of different tools the last time, and it was frustrating. If I was planning a long tour, I'd swap out the rear derailleur cable in advance of the tour.

The symptoms are: 1. sluggish shifts. 2. a few missed shifts and misadjusted cog rubbing noises. 3. very sloppy. 4. snap! (Phase 2 through 4 usually happen within the same ride.)

The older style Shimano shifters with the straight cable housing coming off the side of the shifter might last longer? But they must have a rotating piece to do the shifts, so they would have a similar flexing problem.

so stick it inside your right side handlebar grip.
you'll never see it to worry about it again.
and who knows, you might need to garotte a terrorist.

anyways, you could save the same amount of
weight by trimming your toe nails.

Replace the one on the bike every year or before a multi-week tour if you have doubts... and get rid of the spare if the weight worries you that much.

Having said that, I have had two cables break at different times on tour -- years apart, but the same bike -- and I did have had spares to replace them.

Cables do break. The only place they break is up at the lever.

It's a metal fatigue process related to the repeated bending onto and off the lever drum. How long this takes depends on how often you shift, so someone riding the roller coaster hills of Connecticut will see shorter cable life than someone where it's flat or where the hills tend to be long grades.

Breakage can be eliminated through scheduled replacement, as is done for elevators. However the schedule depends on how long cables last for you. I wouldn't carry a spare when touring solo, but if touring with friends, we might carry one for the group.

I no longer carry spares. I figure that is sensible given that:
1. You can limp along with a broken cable. It is pretty easy to rig the derailleur with the broken cable to your most used gear.
2. In the US and Europe you will likely never be more than a couple days ride from a bike shop.
3. Cables rarely break and pretty much always show fraying for a long time before they do (you do have to know where to look and actually do it though).

It's happened twice to me on day rides, never on tour. My shifters do a great job of hiding the fatigue point, and as mentioned above it's very hard to pull the broken piece out in the field. The advice about replacing the RD cable before a long tour is good. I did that recently.

If you have simpler shifters, it may not be necessary to replace cables prophylactically (if that's a word). You'll have some warning when the fraying wire starts poking your hand (so to speak).

I still carry a spare on long tours because it's easy and light, but no longer have one in my seat pack. It's easier to ride home with a crappy three-speed than to fix it in the field.

I always carry one spare shifter and one spare brake cable on tour. In all the years I've carried them, I've only once used one and that was for a fellow rider whose cable had not broken completely but had become frayed within the housing making it difficult for her to shift to all her gears. Ideally I would have liked to change out the cable housing as well but I guess that's where I draw my line as in what to carry.

Just an additional thought...
On my bikes with down tube shifters, shift cables last pretty much forever. On my bikes with brifters they do tend to eventually fray in a spot hidden in the brifter. They give plenty of warning if you make it a point to look there once in a while. So no need to carry a spare IMO.

On a couple of my bikes I need a tandem length derailleur cable. The odds of finding one of those in a small town is pretty small. I probably do not need to carry a brake cable, but carry one anyway. Most of my tours have been in places where I needed both brakes.

I was wondering what that was that felt sharp on my fingers under my right hand bar end shifter. This also explained why my derailleur needed frequent adjustment.

For a long time I believed the talisman theory of cables; carry one and the one on your bike will never break. But even though I've never had it happen to me I've heard stories of it happening to other people.

Seriously, I don't carry derailleur cables any more because it's not a disaster if one breaks. I'd just put the chain on the small ring and middle of the cassette and ride in a 50" gear to the nearest bike shop. Brake cables are a bit different and I still carry one of those as I never want to be on a descent on one set of brakes.......just in case that cable breaks too.

They break at the brifter. I've also had a cable kink or fray and need replacement due to overbending during shipping. Since most of the cable is usually still there, you just tie it off to the frame somewhere with enough tension to select your favorite SS cog, and behold you have a 3 speed bike if you have a triple. Back to the days of your English Racer!

Preventative Maintenance... Replace the cables shortly Before You leave, Then, rather than guess how much Wear life you Have Left ..

My old frame needed a tandem cable for the RD. I will always carry one of those if the bike necessitates it. Otherwise, no.

In the grand scheme of things the 3-4 ounces that a spare cable weighs as well as the room it takes up is minuscule. If it make you feel better carry one, or not. I cleaned out an old seat bag of mine that I used for road riding a long time ago. There were a spare brake and a spare derailleur cable in there. Probably been in the bag over 20 years. Obviously never needed on a ride. Funny thing though, on the way back from the grocery store the other evening I broke the shifter cable on my city bike, Nexus 8 hub, no spare on the bike or in my shop. Used my last spare on my son's bike and forgot to order more. Oh well, trip to town will take care of it.

Aaron

In my experience, brake cables rarely fail. Only derailleur cables seem to fail, from inadequate bending radius/shifter design limitation/fatigue.

As mentioned earlier, brifters tend to eat cables. I have much more experience with SRAM grip shifters, and they never ate a cable, because the greater bending radius doesn't fatigue the cable wires as much as brifters.

My top pull / top swing XT front derailleurs would eat gear cables every 6 months/3-5,000 miles. As my bottom pull FDs lacked the same short radius pulley mechanism, there was no cable bend and no failures.

Never had a rear derailleur cable fail until I incorporated a Jtek adapter to marry a Campy Ultrashifter to a XT RD.

Bending cables = BAD.

Coincidentally my next bike build will probably use a bottom pull FD and SRAM grip shifters, so I expect carrying a spare gear cable will be unneccessary.

The peace of mind that a brake and RD cable brings is less than the weight effect.
I carry tools that weigh more than the cables but I like to have the minimum items to keep me riding. I don't like the idea of walking 25 miles in cycling shoes to reach a bike shop.

Exactly. It ways next to nothing. A pretty ridiculous thing to worry about. This is bicycle touring not back packing where you cut the tabs off of tea bags to save weight.

To the OP, it's ever a "Waste"... 20 Years of not worrying cause you were prepared is worth a lot...

The only derailleur cable that I have ever broken (in over half a million miles of riding) broke near the front derailleur. Fortunately, we were near the top of Petrified Forest Rd, about to drop into Calistoga in Napa County so we could just lock down in the middle ring and roll into town for a breakfast break while we waited for the bike shop to open. While the shop didn't have any tandem cables, my tandem doesn't need those since the stoker handles the shifting.

I'd only carry spare cables if I was going to be very far from a shop with a lot of interesting terrain to deal with.

I really don't get all this talk about worry.

First... It isn't like it is a part that fails often. If you check your cables once in a while you will probably never break one. I have been riding deraileur equipped bikes since they became popular in the US and have worn out a few cables, but have never had one break.

Second... Even if one breaks you can rig that derailleur to be in the gear you choose and still shift the other one. So it isn't like you would be stranded.

Carry one or don't. The risk is small for not carrying it and the penalty is small for carrying it. Personally I choose not to, but either way it isn't something worth worrying much over.

I agree, basically, but some people have "safety genes"... survival instinct... Whatever...