Breaking cables

[Ranger]

I seem to be having a problem with gear cables snapping (particularly rear) having broken 3 in the last 6 months.

Any advice on what could be causing this or ways to try and stop it?

 

[John the Monkey]

Not without knowing where/how they're snapping.

Is it at the clamp bolt? At the shifter end? Is fraying visible before they snap?

 

[Ranger]

At the shifter end, there does seems to be fraying before it goes

 

[John the Monkey]

What sort of shifters?

My guesses would be either that you're not seating the cable in the holder properly, or that something in there has developed a sharp edge. I've had something similar happen with brake cables (the rotating "drum" type thing that held the cable corroded in place, and instead of rotating was static when the lever was pulled. This meant that the cable went over a metal edge every time the lever was pulled (instead of the drum rotating to allow a straight pull) and the brake cable would fray on that edge.

 

[fossyant]

Do check if possible for any sharp edges. ON STI's the mechanism just pulls the cable round so shouldn't be too big an issue.

Other question.....

Where does the bike live - i.e. outside all day...and what 'quality cables' have you been using.........have you changed the 'outers' at the same time as new 'inners' ?