Below is a photo of my Shimano rear derailler cable after approx. 5,000 miles use. I haven't been in cycling long enough to know, but my mechanic was appalled! My shifters are Shimano 6800 series (on a Spec. Roubaix). The mech. even contacted Shimano to ask about getting me a new shifter; he feels that there is a design flaw of some sort that results in the shifter "chewing up" cables like that. No-go on replacement from Shimano, but I am very glad to know what to check on when my usually flawless shifting goes haywire. Anyone have similar experience?

Replace it before it fails, Next time .. It's Preventative Maintenance ..

the old cable out the side brifters had less cable bends ..

my bar end shifters seem to take the flexing ok for many years..

my 10 speed 105 5700 right hand shifter chomped up the cable in the shifter @ about the 10000km mark. Its the first time I have every seen that, maybe thats their life span? I normally change the cable inner and outer around that mark anyway as I ride all weather year round.

5K miles is not unusual for a shifter cable to fail. Some people have better luck than others of course but I don't see why your mechanic would be appalled. I always check for fraying about every 1k miles but you'll usually notice the shifting will start to get sloppy and act as though it's out of adjustment as the cable starts to fray and elongates. Replace it, ride on and consider it as regular maintenance.

You are fortunate that you caught it before it broke completely; getting the broken-off head out is a painful process. Best to check the cable frequently and replace it as soon as any fraying at all is apparent.

I've gone to replacing the rears every year (3K miles). I start noticing it on the low to high shifts where the RD spring is doing the work.

[QUOTE=casjr2171;18312074but my mechanic was appalled! My shifters are Shimano 6800 series [/QUOTE]

How much work on bike does you mechanic do? As others have noted, this is expected with Shimano STI's 5000 miles is more than enough to have swapped the cable at least once. Surprised your mechanic wasn't aware/hadn't seen this before.

5000 miles on a shifter cable isn't that bad actually.

Yup, shifter/brake cables are "consumables" just as tires/tubes, chains/cassettes and brake pads are.

Yes, I'm finding that out . . . 5K miles not bad for cable life. I couldn't figure out why shifting was "off." Never failed completely, but looks like it had maybe 2 shifts left in it!