The 585

Hey guys, so on my bike commute home today I noticed the shifter for my rear derailleur didn't seem to be catching as well and required extra presses to get it to shift. After some quick research, it seemed like spraying out and re-lubing the shifters might help. I tried that and it's even worse... it seems that the shifter will catch and let it move to the bigger cogs, but then it won't shift back to the smaller cogs. Front derailleur is totally fine.

Any advice or suggestions on what can be done to fix this? If it isn't easy I'll probably take it to my LBS. Thanks in advance!

shelbyfv

Check your cable.

Drew Eckhardt 

1. Cables break strands due to fatigue bending around the shifter drum and 90 degree internal guide allowing under bar tape routing having hoods level with the bar top. That can happen in a few thousand miles depending on how much you shift. I got 4500 miles from rear cables before the routing change, 2500 after, and the last two broke at 1300 + 1500 miles with some sort of metalurgical or processing change in the last batch of cables. I'm replacing mine every 1000 miles until I get different shift cables.

You need to investigate that, because fishing out a broken off end is much more work than changing the cable before the last strands break.

2. Cable housings develop high friction as the cable wears a groove in the lining which pinches it.

I can get about 4000 miles out of rear housing from shifter to frame stop, but replace every 2000 miles when I'm taking care of my cable so I don't have any degradation in shift quality.

3. The rear loop gets dirty.

Those take about 5000 miles to go high friction for me, but it's less trouble to just cut another foot off the roll and replace it with the rest of the housing.

When replacing housing I unwrap my bar tape to the shifter and re-wrap after housing replacement using a fresh piece of electrical tape on the end. I reuse the same tape until it tears.

Note the distance your cable took to fail, and be more proactive next time so you needn't deal with it during an inopportune time.

I keep a Google Docs file noting every bicycle maintenance event and mileage at which things wore out. Before cloud applications it lived on my laptop.

The 585

Bingo... thanks guys. You were spot on. I didn't even think to check the cables, but I looked under the hood and sure enough the cable is frayed/broken. I think this'll be a job for my LBS.