Martian63

First let me state that I am a rookie to road biking. I am having some shifting issues with occasional jumping a cog usually downshifting. Had a new chain and cassette installed last week end and the mechanic at my LBS told me that I have cable issues. I have just over 3500 miles on the bike since I bought it in January of this year. Question for some of you more experienced guys, does this sound about right? Thanks from a newbie!

EvilWeasel

It's certainly possible. How long since your last tune up? Cables don't stay adjusted/ last forever.

FBinNY 

Right? who knows. But it's a definite maybe.

Sticky or worn cables are probably the number one cause of erratic shifting. It usually doesn't affect downshifting because you hand strength is able to overcome any cable friction. But downshifting, which depends on the RD return spring can suffer pretty badly, with issues of delayed shift or poor trim after a shift being common.

As far as whether this should be an issue at 3,500 miles, that's impossible to say because conditions vary so greatly. For example riding in the rain can cause water to wick in carrying fine road dirt. When the water dries, the dirt is left in the cable, and repeated wet/dry cycles can mess up cables pretty quickly. There are other factors, but that serves as an example.

Here's a simple diagnostic for cable friction. Run through the gears a few times, then go to low and upshift one gear at a time, looking for one where it doesn't trim well. If you don't find any, the cables are fine (or at least OK). But if you do find one where the trim is bad, pluck the bare wire away from the frame like a guitar string, and if that corrects the trim, you know that the RD was hanging up because of cable friction.

You can try to solve this by putting a drop of light oil, or oil/OMS mix, at the ends of the housing, and using gravity and repeated shifting to work it in. If that solves it you've saved a few bucks for a while. Otherwise, if the cables continue to cause poor shifting, replacement may be the right answer.

desertdork

Slightly off topic: Do you know how to check your chain for wear? Unless you allow the chain wear significantly (i.e., greater than 1% elongation), you can expect the cassette to last two, if not three or more, chains.

Martian63

Thanks all for suggestions. Being a rookie this is a learning experience. Since I sweat profusely I'm thinking maybe some of the sweat dripping off the top rail has migrated into the cable housing. I now wipe the exposed cables with a light oil after each ride but may be too late for these cables.

Martian63

Sure do desertdork. Have a Park Tool chain checker.