Rear Gearing Issues

My latest maintenance learning is all about the rear derailleur and gearing. On a ride a short while ago, I noticed my gears were skipping – phantom changes and unresponsive or delayed shifting. This was particularly noticeable when the drivetrain was under torque i.e., when climbing. I could be in an easier gear and find the bike shifting up to the next hardest or even the one after that – obviously not good for the bigger climbs, and the sudden and unexpected jump could cause my feet to slip on the pedals which was painful at times.

Not really knowing what the exact cause of this would be, off to the internet I went for research and found a number of possibilities – dirty jockey wheels, a bent hanger, damaged cage, dirty or seized derailleur mechanism, stuck chain link, damaged gear cable, stuck shifter…

I was pretty confident the shifter was okay. It would click up and down fine with each operation. I was also happy that the chain and cassette were fine with me cleaning them regularly and they only being a few months old. So, I started first with giving the derailleur a thorough clean including lubrication first with WD-40 then some oil to make sure it wasn’t seizing. When that made no difference, I moved on to the jockey wheels, removing them, taking everything apart, thoroughly cleaning, re-greasing and reassembling.

Disassembled Jockey Wheel

Then when testing the shifting, the gear cable snapped!

I was pleased this had happened; it seemed obvious that this must have been the problem all along. So, I sourced and installed a complete cable replacement set (outer and inner). Confident this would have sorted the problem, I took the bike out for a 20 mile ride.

This was a mistake and an important learning point – don’t do long test rides. The shifting felt fine at first but I soon noticed some skipping again (though maybe not quite so bad). Combine with a noisy chain sounding like it wasn’t quite seated on the selected cog properly, it indicate to me that the indexing was probably off. I eventually stopped at a cafe and made use of an outside bench to flip the bike over in an attempt to properly adjust it. This is where I noticed a problem with my cable installation.

The barrel adjuster was far too loose and had become completely unscrewed as part of my earlier, smaller mid-ride indexing adjustment attempts. Reseating it required some brute force but I got there in the end, setting its position to around a mid-point on the thread and then readjusting the cable tension. However, I had a lot of difficulty getting the derailleur to shift across all gears. Being ten miles away from home I was a little worried that I wouldn’t get it working well enough and for the first time might need to call for a taxi, but after about 20-30 minutes of repeated tinkering on the cable tension along with fine tuning with that barrel adjuster, I eventually got it to work across all except for the easiest gear – good enough for the ride home.

Now I was starting to wonder if the derailleur itself was failing and I started to look at a suitable replacement. Not quite ready to give up though, I decided to try another thorough clean of the chain and cassette to be absolutely sure grit and grime wasn’t the cause. I gave both the most thorough de-greasing and scrubbing I’d ever done and relubricated the chain, checking each link to be sure none had seized; all was fine but still the issue persisted – I’d not had much hope that this would solve the problem.

Finally, I decided on one last re-indexing attempt, making sure I looked at all three adjustment screws. I got the shifting to work well with the bike inverted in the kitchen but this wasn’t unusual in itself – I’d found before that shifting would be fine in the workshop-like environment but would exhibit the problems when out on proper rides including going up hills.

Derailleur Adjustment Screws

This time however it was different. At this point I was pretty sure replacing the derailleur would be the route I’d want to go down, but to my utter surprise, when doing one final test ride the next day, everything worked! All gears were selectable across the entire range with none being skipped; shifting was quick, stable and quiet; no phantom shifts; no jumping down the gears on its own accord. My test included a rough up-hill route on which I need the easier gears – exactly the sort of hill where I originally noticed problems with the easier gears not being stable – and it worked absolutely fine!

I’ve done a number of short range rides of around 5-6 miles and one longer journey, and I’m happy that the problem is solved. I’m putting the problem initially down to that worn cable (obviously) but then coupled with my own inexperience with indexing and adjusting which prolonged the fault even after that cable was replaced. I’m pleased that I managed to get this solved, especially since I’ve got no local bike shop to help bar Halfords, and hopefully next time this happens, I’ll be a bit more prepared.

One thing I definitely need though is a maintenance stand. Working on a flipped-over bike on the ground is not particularly comfortable or easy!