We have a customer who use to break 2 or 3 cables a year. After a few years we finally trained him to have his cables replaced every 3 or 4 months. he hasn't been stranded since.

Some context- he rides 8K-10K miles a year in VT and the Finger lakes of NY, he's big and from what we see of the rest of his bike he rides in all conditions and jam shifts as needed.

We are finding that the new cable routing of the current STI shifters seem to be less fatiguing on the cable then the old external casing versions.

When I do service assessments I pull the rear der's casing loop off the chain stay stop and push the inner cable out of the lever (old version routing) and look at the first half inch of cable. If there's any doubt I suggest a replacement. $5 vs being stranded in high gear and a possible lever replacement... Andy.