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Rear derailleur won't shift onto 2 smallest cogs

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Rear derailleur won't shift onto 2 smallest cogs

Old 04-12-21, 05:53 AM
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Chubby715
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Rear derailleur won't shift onto 2 smallest cogs

Can someone please provide some suggestions on how to correct the index shifting on my rear derailleur and 11 speed cassette. It shifts fine (up and down) on the first 9 cogs of the cassette. But the derailleur body doesn’t move down onto the two smallest cogs when I pedal and click the shifter, even though there’s enough room left based on the limit screw setting.

So far I’ve done the following:

1. Confirmed the limit screw is set correctly.

2. Removed all slack from the cable at the pinch point bolt.

3. Completely tightened the barrel adjuster clockwise.

4. Lubed all pivot points on the derailleur body.

The shifting problem started this weekend after I removed the wheel to fix a flat tire. I’ve reinstalled the wheel correctly into the dropouts. So I’m stumped on why the index shifting doesn’t move the derailleur down any further. Is it possible the hanger needs to be aligned correctly? The bike has never been in a crash or banged up.
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Old 04-12-21, 05:55 AM
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If you're running the chain w/o the rear derailleur shift cable connected AT ALL, and the limit screw isn't stopping the rear derailleur from letting the chain run to the smallest cogs, then either 1) the wheel isn't seated properly, or 2) something's bent.
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Old 04-12-21, 06:25 AM
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Got a bent rear derailleur hanger?
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Old 04-12-21, 06:40 AM
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When you reattached the cable to the derailleur did you ensure that the derailleur and the shifter were both in the highest gear position, that is, on the smallest cog and with the most cable payed out from the shifter?
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Old 04-12-21, 07:45 AM
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Did you try it with the cable removed from the pinch bolt? If it will go down to the 11th cog with the cable removed, then I'd expect that the cable is binding somewhere. Maybe frayed up in the STI or shifter housing.

If it still won't shift itself to the smallest cog with the cable removed from the rear DR, and it shifted fine before, then you either bent the hangar or you got something wrong when you put the wheel back in.

Notice I called it a pinch bolt, got that from the OP..... I'm hoping cxwrench likes that instead of me calling it a holdfast. <grin>
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Old 04-12-21, 08:05 AM
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Iride01 Calvin Jones of Park Tool calls it a pinch bolt so there you go.

When I loosen the pinch bolt / remove tension on cable, the derailleur still doesn't freely move onto the last two cogs. But it moves only if I use my fingers and gently pull the derailleur body outward. And the derailleur body moves smoothly with the rear wheel removed.
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Old 04-12-21, 09:16 AM
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If I read this correctly, the RD will not return to the 1st/2nd cog position with the cable detached and the wheel installed; but you can physically move it there. With the wheel removed and the cable detached it will move completely to the limit screw.

I would probably make sure the derailleur, especially the return spring is thoroughly cleaned and there is no buildup. Just lubing the pivots may not be enough. Adjusting the B screw might give a bit more clearance for the chain and jockey wheel and help with the shift.

John
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Old 04-12-21, 09:42 AM
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Originally Posted by 70sSanO
If I read this correctly, the RD will not return to the 1st/2nd cog position with the cable detached and the wheel installed; but you can physically move it there. With the wheel removed and the cable detached it will move completely to the limit screw.

I would probably make sure the derailleur, especially the return spring is thoroughly cleaned and there is no buildup. Just lubing the pivots may not be enough. Adjusting the B screw might give a bit more clearance for the chain and jockey wheel and help with the shift.

John
thank 70sSanO for the suggestions. There's definitely no buildup on the derailleur as I keep all the parts clean after riding in inclement weather. I even blasted it with compressed air yesterday to ensure there's no grit causing it to bind. But I didn't confirm it moves all the way to the limit screw with the wheel removed AND cable detached. That will be my next check tonight.

I also have a brand new rear hanger in my parts collection so can install that as a last resort. I could have bent the hanger when reinstalling the wheel after fixing the flat. It was a roadside repair so I didn't have access to a work stand.
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Old 04-12-21, 09:49 AM
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Originally Posted by Chubby715
Iride01 Calvin Jones of Park Tool calls it a pinch bolt so there you go.

When I loosen the pinch bolt / remove tension on cable, the derailleur still doesn't freely move onto the last two cogs. But it moves only if I use my fingers and gently pull the derailleur body outward. And the derailleur body moves smoothly with the rear wheel removed.
If that's the case, and you routed the chain correctly, though I can't really imagine how you wouldn't if you didn't undo the chain, then it will almost have to be a gunked up DR mechanism. Is it filthy? Or possibly an ever so slightly bent hangar.

The comment about pinch bolt was an ongoing thing between me and cxwrench . A humorous ongoing thing I hope. Several times he expressed displeasure at me referring to the pinch bolt as a holdfast. I think he prefers the term cable clamp.

I just think it doesn't matter. By the definition of holdfast it is a holdfast. Maybe it's more proper in sailing jargon than bike jargon though.
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Old 04-12-21, 10:52 AM
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The hanger would have to be bent a TON for it to keep the derailleur from shifting to the 2 smallest cogs, let alone just the smallest cog. A bent hanger has the least affect in the small cogs, the most in the big cogs, geometry being what it is. If this isn't a cable/housing problem I'm at a loss for the cause.
And yes Iride01 , definitely humorous.
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Old 04-12-21, 11:04 AM
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I might suggest looking at from the rear of your bike at the same level as the cassette to the chainwheel. What's the chain line look like on the top and maybe compare how that looks between it and the bottom.

While you are back there follow the chain visually as it wraps around and goes down into the jockey/pulley wheels. Anything look off? Pic's of that and from the side might help us. There is a gallery here on BF if you need it to upload to..

But it's sounding like you need to clean and lube the DR or something on the DR is futched up. Maybe a spring broke.
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Old 04-19-21, 08:26 AM
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I believe the culprit is the cable. I removed the pinch bolt and the RD slides freely down to the limit screw. But when I pull the cable and click the shifter, the cable doesn't slide easily for the last two positions. I forgot to mention I'm running Dura Ace polymer coated cable and they're known to wear down after a year. So am installing a new cable later this week.
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