Chain too Short?

[Harry 'Snapper' Organ]

I have just got a bike with one of these Shimano granny gears
considerably larger than the other gears. Its a roughy I want to use
to go to the library and shopping etc

The deraillier is a cheap one but seems to be designed for these gears
(it says so on the arm!). but it doesn't have a screw adjusting its
distance from the gear teeth and the inner most cog touches the
largest cog. (I don't mean the two screws which act to limit the
derailleur travel from high to low gear I mean the one which restricts
the ammount the small cogs can be pulled toward the sprockets by
tension in the chain)

I suspect that the chain is too short - perhaps these larger gears and
deraillers have been added but the original chain left on. Does this
sound right to you?

I have a new chain to fit and will follow the Richards' advice on the
length of the chain but I wonder if anyone has any other advice.


Regards
Harold

Timendi causa est nescire

 

[John Henderson]

Harry 'Snapper' Organ wrote:

> I have just got a bike with one of these Shimano granny gears
> considerably larger than the other gears. Its a roughy I want
> to use to go to the library and shopping etc
>
> The deraillier is a cheap one but seems to be designed for
> these gears (it says so on the arm!). but it doesn't have a
> screw adjusting its distance from the gear teeth and the inner
> most cog touches the largest cog. (I don't mean the two screws
> which act to limit the derailleur travel from high to low gear
> I mean the one which restricts the ammount the small cogs can
> be pulled toward the sprockets by tension in the chain)
>
> I suspect that the chain is too short - perhaps these larger
> gears and deraillers have been added but the original chain
> left on. Does this sound right to you?
>
> I have a new chain to fit and will follow the Richards' advice
> on the length of the chain but I wonder if anyone has any
> other advice.

Two reputable articles addressing this issue:

http://sheldonbrown.com/derailer-adjustment.html#chain

http://www.parktool.com/repair/readhowto.asp?id=26

John

 

[NickP]

If the chain is long enough to allow large chainring and large cog at the
rear then it's not too short.

The problem you describe will usually be made worse by lengthening the
chain, as the pivot point for the derailleur cage is usually below the upper
jockey wheel.

The Park web site has a good article on chain length:
http://www.parktool.com/repair/readhowto.asp?id=26.

Nick

"Harry 'Snapper' Organ" <[email protected]> wrote in message
news:[email protected]...
>I have just got a bike with one of these Shimano granny gears
> considerably larger than the other gears. Its a roughy I want to use
> to go to the library and shopping etc
>
> The deraillier is a cheap one but seems to be designed for these gears
> (it says so on the arm!). but it doesn't have a screw adjusting its
> distance from the gear teeth and the inner most cog touches the
> largest cog. (I don't mean the two screws which act to limit the
> derailleur travel from high to low gear I mean the one which restricts
> the ammount the small cogs can be pulled toward the sprockets by
> tension in the chain)
>
> I suspect that the chain is too short - perhaps these larger gears and
> deraillers have been added but the original chain left on. Does this
> sound right to you?
>
> I have a new chain to fit and will follow the Richards' advice on the
> length of the chain but I wonder if anyone has any other advice.

 

[Bean Long]

NickP wrote:
> If the chain is long enough to allow large chainring and large cog at
> the rear then it's not too short.
>
> The problem you describe will usually be made worse by lengthening the
> chain, as the pivot point for the derailleur cage is usually below the
> upper jockey wheel.
>
> The Park web site has a good article on chain length:
> http://www.parktool.com/repair/readhowto.asp?id=26.
>
> Nick
>
> "Harry 'Snapper' Organ" <[email protected]> wrote in message
> news:[email protected]...
>> I have just got a bike with one of these Shimano granny gears
>> considerably larger than the other gears. Its a roughy I want to use
>> to go to the library and shopping etc
>>
>> The deraillier is a cheap one but seems to be designed for these gears
>> (it says so on the arm!). but it doesn't have a screw adjusting its
>> distance from the gear teeth and the inner most cog touches the
>> largest cog. (I don't mean the two screws which act to limit the
>> derailleur travel from high to low gear I mean the one which restricts
>> the ammount the small cogs can be pulled toward the sprockets by
>> tension in the chain)
>>
>> I suspect that the chain is too short - perhaps these larger gears and
>> deraillers have been added but the original chain left on. Does this
>> sound right to you?
>>
>> I have a new chain to fit and will follow the Richards' advice on the
>> length of the chain but I wonder if anyone has any other advice.
>


--
Bean

"I've got a bike
You can ride it if you like
It's got a basket
A bell that rings
And things to make it look good
I'd give it to you if I could
But I borrowed it" Pink Floyd

Remove "yourfinger" before replying

 

[Bean Long]

Harry 'Snapper' Organ wrote:

> chain length suff <snipped>

A good rule of thumb is that when the chain is on the big chain ring and
largest sprocket (i.e. full stretch - please correct me if that's the
wrong gear combo) the jockey wheels (pulleys) should be directly one on
top of the other. If the tension pulley (bottom jockey wheel) is too far
forward then the chain is too short.
--
Bean
Remove "yourfinger" before replying

 

[Bean Long]

Ooops! Apologies... brain too short!

--
Bean


Remove "yourfinger" before replying

 

[Harry 'Snapper' Organ]

On Fri, 12 Oct 2007 17:22:47 +1000, Bean Long
<[email protected]> wrote in aus.bicycle:

>Harry 'Snapper' Organ wrote:
>
>> chain length suff <snipped>
>
>A good rule of thumb is that when the chain is on the big chain ring and
>largest sprocket (i.e. full stretch - please correct me if that's the
>wrong gear combo) the jockey wheels (pulleys) should be directly one on
>top of the other. If the tension pulley (bottom jockey wheel) is too far
>forward then the chain is too short.

Yes that is the way I have always understood it to be done


Regards
Harold

Tantum religio potuit suadere malorum - Lucretius

 

[Harry 'Snapper' Organ]

On Fri, 12 Oct 2007 17:22:47 +1000, Bean Long
<[email protected]> wrote in aus.bicycle:

>Harry 'Snapper' Organ wrote:
>
>> chain length suff <snipped>
>
>A good rule of thumb is that when the chain is on the big chain ring and
>largest sprocket (i.e. full stretch - please correct me if that's the
>wrong gear combo) the jockey wheels (pulleys) should be directly one on
>top of the other. If the tension pulley (bottom jockey wheel) is too far
>forward then the chain is too short.

Yes that is the way I have always understood it to be done


Regards
Harold

Tantum religio potuit suadere malorum - Lucretius