Hub gears on a horiz-dropout frame?

[James Thomson]

>> My aunt's Twenty came with a half link. Series 1 and 2 Moultons
>> came with a half link, and many older hub-geared roadsters I've
>> seen have a half link even when the length of the dropouts makes
>> it unnecessary.

>> I've often wondered why. My feeling was that it was seen as a
>> normal feature at the time to be able to adjust a new chain by
>> half a link if necessary,

"Pete Biggs" <removehighlyimpracticalfruitbiggs.tc> volunteered:

> It's so you can adjust by removing the half link when the chain
> is so stretched that you can't shove the wheel back enough to
> compensate.

Well, yes. The question is why use a half link when there's (generally)
ample room in the dropouts to adjust by a full link pair at a time?

I guess it makes sense to minimise axle movement when dealing with rigid
steel mudgards and chaincases. But then why provide long dropouts?

>> vintage chains I've bought (Coventry and Renold)
>> haven't come with a half link in the packet, so I'm not
>> sure that that theory holds water.

> They weren't so thoughtful.

I'll add Brampton and Sedis to that list. Do you know of any vintage chain
manufacturers who were "thoughtful" in this regard, i.e. who sold chains
packaged with half links as a matter of course?

James Thomson

 

[Pete Biggs]

James Thomson wrote:
>>> My aunt's Twenty came with a half link. Series 1 and 2 Moultons
>>> came with a half link, and many older hub-geared roadsters I've
>>> seen have a half link even when the length of the dropouts makes
>>> it unnecessary.
>
>>> I've often wondered why. My feeling was that it was seen as a
>>> normal feature at the time to be able to adjust a new chain by
>>> half a link if necessary,
>
> "Pete Biggs" <removehighlyimpracticalfruitbiggs.tc> volunteered:
>
>> It's so you can adjust by removing the half link when the chain
>> is so stretched that you can't shove the wheel back enough to
>> compensate.
>
> Well, yes. The question is why use a half link when there's
> (generally) ample room in the dropouts to adjust by a full link pair
> at a time?

Don't know the answer if the dropout really is long enough for that, but I'm
not sure it is that general for horizontal dropouts to be that long.

I could not have removed a whole pair of links from the Dawes Nexus bike I
was trying to fix the other day with a slack chain. A half link would have
done the job but unfortunately there wasn't one. Didn't help that the bolt
to secure the roller brake gets in the way too and effectively makes the
dropout even shorter.

I resorted to replacing the bolt with a thinner one while I order a new
chain and sprocket.

~PB

 

[Pete Biggs]

I scribbled:

> I could not have removed a whole pair of links from the Dawes Nexus
> bike I was trying to fix the other day with a slack chain. A half
> link would have done the job but unfortunately there wasn't one. Didn't
> help that the bolt to secure the roller brake gets in the way
> too and effectively makes the dropout even shorter.
>
> I resorted to replacing the bolt with a thinner one while I order a
> new chain and sprocket.

This enabled the wheel to be moved back enough to get just-about good enough
chain tension.

~B

 

[James Thomson]

>> The question is why use a half link when there's
>> (generally) ample room in the dropouts to adjust
>> by a full link pair at a time?

"Pete Biggs" <[email protected]> a écrit:

> Don't know the answer if the dropout really is long enough for
> that, but I'm not sure it is that general for horizontal dropouts
> to be that long.

The bikes I'm talking about, classic roadsters and early Moultons that were
supplied with half-links, had long dropouts.

Only half an inch of axle movement is necessary to tension a normal chain
with any combination of chainring and sprocket. Any hub-geared bike with
shorter dropouts is designed by morons. They exist, of course.

> I could not have removed a whole pair of links from the Dawes
> Nexus bike I was trying to fix the other day with a slack chain.
> A half link would have done the job but unfortunately there wasn't
> one. Didn't help that the bolt to secure the roller brake gets in
> the way too and effectively makes the dropout even shorter.

You did make sure the anti-rotation washers were fitted tabs-out?

A few manufacturers are now making chains that consist entirely of half
links:

http://www.chainreactioncycles.com/Models.aspx?ModelID=12076

James Thomson

 

[Pete Biggs]

James Thomson wrote:

> The bikes I'm talking about, classic roadsters and early Moultons
> that were supplied with half-links, had long dropouts.
>
> Only half an inch of axle movement is necessary to tension a normal
> chain with any combination of chainring and sprocket. Any hub-geared
> bike with shorter dropouts is designed by morons. They exist, of
> course.

I have to confess to beng a moron myself....

If I shorten the chain by 1 inch, I was thinking the axle has to move by 1
inch to compensate. But it's half an inch, is it?

>> I could not have removed a whole pair of links from the Dawes
>> Nexus bike I was trying to fix the other day with a slack chain.
>> A half link would have done the job but unfortunately there wasn't
>> one. Didn't help that the bolt to secure the roller brake gets in
>> the way too and effectively makes the dropout even shorter.
>
> You did make sure the anti-rotation washers were fitted tabs-out?

Yes

~PB

 

[Rob Morley]

In article <[email protected]>, Pete Biggs
[email protected] says...

> If I shorten the chain by 1 inch, I was thinking the axle has to move by 1
> inch to compensate. But it's half an inch, is it?
>
Slightly less, assuming the chainring and sprocket aren't the same size.

 

[David Damerell]

Quoting James Thomson <[email protected]>:
>Well, yes. The question is why use a half link when there's (generally)
>ample room in the dropouts to adjust by a full link pair at a time?
>I guess it makes sense to minimise axle movement when dealing with rigid
>steel mudgards and chaincases. But then why provide long dropouts?

Why have short dropouts specially made?
--
David Damerell <[email protected]> Kill the tomato!
Today is First Leicesterday, December.

 

[James Thomson]

"David Damerell" <[email protected]> a écrit:

>> I guess it makes sense to minimise axle movement when
>> dealing with rigid steel mudgards and chaincases. But then
>> why provide long dropouts?

> Why have short dropouts specially made?

In the Moulton's case, everything was specially made.

There's another possible justification for a half link on the Series 1 and 2
Moultons in that the rear brake position on the rear fork, just behind the
pivot, means that brake adjustments are necessary to compensate for axle
movement. That doesn't hold for the Raleigh Twenty though.

In the case of roadsters from Raleigh, Rudge etc. the dropouts would have
been made in-house, and roadsters dominated the market. It would seem
strange to go on using such a simple part on hundreds of thousands of bikes
simply because it existed already.

James Thomson