Rear Mech not moving when shifiting

chris_bass

I am having issues when shifting from smaller gear to larger ones at the rear.

I have indexed my own gears for years and know what to do so it isn't an issue with not enough tension in the cable, but when i click the shifter once the rear mech doesn't move at all (whilst cycling on a straight quiet road I can change gear and watch the rear mech and it either moves a tiny amount or not at all), but if you click it twice it shifts up one gear and then click it back down once and it stays where it is. Shifting from larger gears to smaller ones is fine all the way down the cassette.

I have tried changing the gear cable and it is still the same. I have now bought some proper shimano gear cables and outers which I am going to fit this weekend, but thought I'd ask if there is anything else I could try whilst i'm looking at it?

It is shimano 105 shifter and mech.

jgsi

Get the cabling done and at same time give the rear mech a thorough cleaning in diesel bath ensuring that it pivots cleanly. When you re cable check the routing if that might be making things difficult as you tape the cable to the bars and the loop at the back of the mech itself.

desweller

It'll be the outer housing. Most likely the rear loop to the derailleur.

Inner cables don't really wear out unless they've been fretting on something.

You can sometimes get more life out of the rear loop by removing the end caps and squirting some WD40 through the housing. I like to fire some SP90 (silicone spray) through the housing as well as it leaves a nice slippery silicone deposit in there. You can also switch end so the inner cable runs on an unworn piece of the PTFE/nylon liner in the housing to get a bit more life out of it. But if you refit the old inner cable make sure you thoroughly wipe any accumulated debris off it before you thread it back through.

chris_bass

Thanks, I'll change the cables and outers and give everything a good clean and hopefully that'll do the trick