When to Replace Gear Cable?

[roubaixtuesday]

And then what did you do?
Presumably not replace it mid ride?

I learned this lesson years ago, the pain from the remaining 50 miles on a century ride through the Yorkshire Dales lives with me to this day.

I carry a spare in my toolkit and ensure a screwdriver small enough for the annoying shimano cover is in too. It takes 10 minutes to do.

In a period last year I actually changed three in as many weeks: Tandem, solo bike and son's bike. It's easy if you know how to get the end out and have a screwdriver.

I've probably done it half a dozen times mid ride altogether.

 

[C R]

where did it snap though? as in where on the cable, not on B4204 thru Lower Broadheath

In the shifter, the usual place.

 

[C R]

And then what did you do?
Presumably not replace it mid ride?

Set the limit screw in the rear derailleur to the lowest gear it would go, sixth I think, and made it home with two gears. Luckily I wasn't too far and it is fairly flat around here anyway.

 

[Ming the Merciless]

where did it snap though? as in where on the cable, not on B4204 thru Lower Broadheath

That road is notorious for snapped gear cables

 

[T4tomo]

That road is notorious for snapped gear cables

My OH's snapped on the turbo trainer, it was hell for her getting home....

 

[Ming the Merciless]

My OH's snapped on the turbo trainer, it was hell for her getting home....

Must have covered a lot of distance on the turbo

 

[Ajax Bay]

where did it snap though? [@C R answered]

In the shifter, the usual place.

For shifters where the cable comes out the side (Edit: Per @C R old Sora/Tiagra/older Ultegra) the modal place for a FD cable to part is at the clamp; and second most often is under the BB shell. You want 'hidden' (under bar tape) cables: expect the cable's MTBF to be much lower (because the bowden cable is so tightly bent (and unbent) under tension so it fails by fatigue).

And then what did you do?
Presumably not replace it mid ride?

Mid-ride. For me when this happened (parted at the clamp) I was at ?65km into a 600 (changing down/up to the large ring for the drop to Talgarth). Fail. Cue serious spinning trying to stay on a wheel, on the 30t to Bronllys/Honey Cafe. Remove cable and use limit screws to the middle ring. Ride to Rhyader and the excellent bike shop there. New cable and coffee. Fit; and away (to Llandildoes and beyond).
I then carried a spare cable for a year. But @Ian H counselled that that cable was better use fitted (before the ride) - so as @ianrauk advises: do this annually, both sides.

 

[C R]

For 9sp Sora, the cable comes out the side. The modal place for a FD cable to part is at the clamp; and second most often is under the BB shell.

Not the more recent ones. In mine the cables come out under the bar tape like in 105.

 

[presta]

I once noticed a frayed gear cable the day after I set off on tour, so I stopped at a bike shop and bought another, but by the time I got home the frayed one was still on the bike and the spare still in the pannier. I've never had a cable break.

 

[roubaixtuesday]

I once noticed a frayed gear cable the day after I set off on tour, so I stopped at a bike shop and bought another, but by the time I got home the frayed one was still on the bike and the spare still in the pannier. I've never had a cable break.

The brifters where the cable goes under the bar tape are much more prone to failure than other designs. I presume the radius of the bends is much tighter.

 

[T4tomo]

I presume the radius of the bends is much tighter

It's the angles it bends through in the shifter mechanism as opposed to the under bar cable run that causes the stress. The washing line style exited straight out of the rotating mechanism, the modern ones have to bend has they come out.

 

[palinurus]

I replace them when they break (I have a number of roadside bodges depending on the particularities of the break!- using the limit screw, clamping the cable under a bottle cage bolt...)

On my commute bike I had a period where I'd just replace all cables every spring but I've done away with gears for winter use.

 

[Mazz]

Wish I'd never read this thread...the gear cables in my 1980s Mustang are probably the originals!

 

[faster]

The brifters where the cable goes under the bar tape are much more prone to failure than other designs. I presume the radius of the bends is much tighter.

I don't agree. The bend with the tightest radius is the one where it bends around the pulley on the shifting mechanism. This is much tighter than any of the bends required to run the cable under the bars and it's at this pulley, right next to the nipple, where the cables break.

The cable has to take this bend whether the shifter is 'washing line' or 'under bar tape'.

The shifters that snap cables more often are those with a long lever throw to shift, as these are wrapping the cable around a smaller/tighter pulley. You'll notice that flat bar shifters, which have a really short throw as they are pushed by your thumb (which is comparatively stronger) almost never break cables within the shifter, as the pulley the cable is wrapped around is larger/less tight radius.

My worst shifter by far for snapping cables was Shimano Sora 3400 (really long throw to shift), which was a washing line design.

Washing line vs under bar tape has little to do with snapping cables IMO.

 

[roubaixtuesday]

I don't agree. The bend with the tightest radius is the one where it bends around the pulley on the shifting mechanism. This is much tighter than any of the bends required to run the cable under the bars and it's at this pulley, right next to the nipple, where the cables break.

The cable has to take this bend whether the shifter is 'washing line' or 'under bar tape'.

The shifters that snap cables more often are those with a long lever throw to shift, as these are wrapping the cable around a smaller/tighter pulley. You'll notice that flat bar shifters, which have a really short throw as they are pushed by your thumb (which is comparatively stronger) almost never break cables within the shifter, as the pulley the cable is wrapped around is larger/less tight radius.

My worst shifter by far for snapping cables was Shimano Sora 3400 (really long throw to shift), which was a washing line design.

Washing line vs under bar tape has little to do with snapping cables IMO.

Fair enough