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R. Derailer idler pullies

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John B.

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Nov 20, 2015, 6:06:35 AM11/20/15
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I spent some time cleaned and lubed a 105 rear derailer that I'll
probably use in the new(old) bike. I noticed that the idler pulleys
are extremely loose and wonder whether they should be replaced. The
lower one is probably not too important but the upper pulley is what
derails the chain and I would think that if it wiggled from side to
side it would effect shifting.

Comments ?
--

Cheers,

John B.

AMuzi

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Nov 20, 2015, 8:31:03 AM11/20/15
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It's not a bug, it's a feature.
Shimano calls the top roller design 'centeron pulley'. It's
supposed to slide laterally so as to center under the
sprocket without rocking. Various materials were used across
years and models, the most expensive of which have ceramic
liners over a ceramic bush.

It's a contributing part of an index system, which is to
say that several features combine for snappy index shifting
not just the shifter itself.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971


Lou Holtman

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Nov 20, 2015, 8:47:56 AM11/20/15
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Lateral movement it's OK. It makes the adjusting less critical. I prever pulley that doesn't have lateral play though. If the pulley shows rotational movement along X axes (X is the traveling direction) because of a worn pulley bearing you get sloppy shifting because of the hysteresis. Time to replace the pulleys for me.

Lou

John B.

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Nov 20, 2015, 7:45:07 PM11/20/15
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On Fri, 20 Nov 2015 07:30:57 -0600, AMuzi <a...@yellowjersey.org> wrote:

>On 11/20/2015 5:06 AM, John B. wrote:
>>
>>
>> I spent some time cleaned and lubed a 105 rear derailer that I'll
>> probably use in the new(old) bike. I noticed that the idler pulleys
>> are extremely loose and wonder whether they should be replaced. The
>> lower one is probably not too important but the upper pulley is what
>> derails the chain and I would think that if it wiggled from side to
>> side it would effect shifting.
>>
>> Comments ?
>> --
>>
>> Cheers,
>>
>> John B.
>>
>
>It's not a bug, it's a feature.
>Shimano calls the top roller design 'centeron pulley'. It's
>supposed to slide laterally so as to center under the
>sprocket without rocking. Various materials were used across
>years and models, the most expensive of which have ceramic
>liners over a ceramic bush.
>

I'll look at it again but my initial impression was that the bushing
was work and it wiggled, i.e. tilted back and forth.

>It's a contributing part of an index system, which is to
>say that several features combine for snappy index shifting
>not just the shifter itself.
--

Cheers,

John B.

James

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Nov 20, 2015, 8:23:23 PM11/20/15
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Yes.

--
JS

avag...@gmail.com

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Nov 20, 2015, 9:23:58 PM11/20/15
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SYNTHETIC BOAT TRAILER BEARING GREASE IS PERFECT FOR IDLERS

buy where you are ?

AMuzi

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Nov 21, 2015, 10:04:38 AM11/21/15
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in that case, it's worn out. They are cheap and myriad
aftermarket products exists besides a host of Shimano models.

John B.

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Nov 22, 2015, 7:20:02 AM11/22/15
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That's what I figured and will replace it :-)
--

Cheers,

John B.
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