This is a well worn piece of equipment with which I have had many joyous hours traversing the local countryside. After a recent hiatus to begin caring for my mother, I hopped back on one morning and noticed my rear derailleur skipping rather unpredictability and I couldn’t understand since nothing had changed in the previous two months. After moving the setup to an old frame I finally noticed that the bottom jockey wheel is receiving the chain *on* its teeth rather than *with* its teeth. Is this simply a damaged derailleur? Or is something to do with my lack of skill in indexing? Something else? As far as I can tell, the limit screws are where they need to be but I don’t know what else could cause this besides a damaged part somewhere in the mix. Any ideas for an answer are appreciated!
Edit: right after posting and suspicion confirmed by early comments, the jockey wheel was on backwards and I also had an inkling small chainring was as well so I flipped both of those. The issue is lessened now however still appears to skip towards the larger rear cogs while on small chainring. Similar on big ring. I’m wondering if something about the bottom bracket could be adjusted to improve chain line or is that not a thing? Failing that shot in the dark I will also take to LBS to inspect hanger alignment.
Edit 2: Thank you everyone! (Un)fortunately I made some slight adjustments that made the lovely “tiptoe” effect vanish but enough skipping remained that when I took it to the LBS the mechanic went directly to the hanger which was indeed bent. I am happy to report that not only is it fixed but I had the jockey wheel on right the first time so now I get to swap that back and move on to the next unknown as I navigate my first (re)build!
by LavenderTed
15 Comments
I have never seen a derailer pulley tiptoe before. Huh.
Does it work if you put the jockey wheel in the other way round?
I’m actually curious how this would affect wear and cleanliness.
I’m not gonna lie. I’ve been at this for 20+ years and I’ve never once seen that. I’ve seen all kinds of other weird, whacked out stuff, but never a pulley that tiptoes.
My first point of check would be chain wear. You said that this is a much loved and much used bicycle. It may be that you have started to wear components out. The second point of check would be the pulleys themselves. They do not look terrible but were and tear can show up in very many strange ways.
A word of note. Once you start replacing things like pulleys and chains, you may find that they have worn together with your front chain rings and your rear cassette as well. Do not be surprised if you start replacing multiple things in order to get back to a functional bike. This is common and normal and accepted.
As a first step I’d bring the bike a local shop and have them check things over. It sounds simple, but even if the derailer hanger itself or the derailleur cage gets bent a tiny bit or twisted then I can cause funny things like this to happen. Your local Shop can check these things very quickly. However, you do need special tools to do so that are not worth buying if you’re not doing it every day.
I had such a result when I had a bent hanger and worn out chain. So I’ve replaced both and it was fixed. Check if it might be your case also.
The B-screw (or B-tension screw) adjusts the gap between the rear derailleur guide pulley and the cassette cogs, affecting shifting performance. A 5–6mm gap is standard, typically adjusted by shifting into the smallest chainring and largest cog, then tightening the screw to increase the gap or loosening it to reduce it.
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looks like it is off center, riding on the outer plates.
Is the side of the cage rubbing the chain? Hanger alignment is the first thing I’d check.
I’ve seen this with extreme cross chaining. If your chainring is too far outboard to line up with the derailleur in this gear it might explain it. Are you in the smallest cog during this video? How about a pic of the chainline (just a pic taken from the rear of the bike showing how the chain runs)
Jockey wheels are cheap!
BTW beware that the two jockey wheels in a derailleur are different – the bottom one (the one on the video) is the tension pulley (aka t pulley) and the top one is the guide pulley (aka g pulley). The t pulley is actually directional (at least in my shimano derailleur). So make sure that 1) the two are not swapped and 2) the t pulley is installed in the right direction.
Old chain, pulley or wrong pulley
Did you put a different derailleur on that bike? Might be meant for a different chain
looks like the angle of the jockey wheel and its carrier is not aligned to the rest of the bike. It looks like it’s pointing inwards a lot! Also it looks to be stamped steel so you can bend that thing back
I would be looking at the one above and/or I’d the cage is bent?