It happens fairly often…. you are out on a ride and you or a friend has a cable that snaps & all of a sudden you are riding home in the smallest cog you have.
I went out for a couple hour ride last week, but it got cut really short. Luckily, I noticed the signs of what was about to happen and I was able to pedal back to the house before it actually did. As I opened up my rear shifter, I could see that about half the cable was frayed. Several more shifts and it would have snapped, leaving me riding home in the 39/11.
My bike had been shifting nearly flawless for many rides. Suddenly on a ride, I am having to over-shift to get into gear. The gears were requiring a little extra input from me….. so I stopped made a slight barrel adjustment to the rear derailleur. That seemed to fix it for the rest of the ride. Next ride, I noticed that once again, the rear shifter was requiring more input, and the gears were ‘ghost shifting’ or wanting to shift with out any input from me. This was happening in several different gears, so I knew this was no coincidence. I stopped at the top of the next climb, grabbed the rear brake level and held it all the way open, looking into the small hole that the shifter cable gets installed through. Sure enough, I was able to see a several strands of cable that were fraying. Being only about 4 miles from the house, I turned around and headed back.
Getting the rest of the cable end & cable out of the shifter is not a task for most – take it too your local bike shop. I spent about 30 minutes getting that sucker out of there, then luckily I had a spare cable (well, I usually do for races and trips) and I re-installed and pre-stretched the new cable. Once again, I head out the door for my ride.
If a cable does break, another way to get home is to adjust the limit screw of the rear derailleur so that the chain lines up a couple of gears higher on the cog. If you know how, you can set the limit screws so that you can be a couple of gears higher than the smallest. Usually on road bikes it is on the very back of the derailleur, and if you tighten the bottom 1, it will push the chain higher on the cog (rear gears). Each cog higher it can be adjusted the easier it will be to spin the gear it is in. This will at least give you 2 gears to ride back with. However, if you know the signs, this can be avoided!