Old Cyclo rear derailleur
Steve Gravrock
<http://www.reneherse.com/ReneHerse1950large.html>
I'm a bit puzzled by the rear derailleur. It seems to be a simple
plunger type, which moves in and out but not up and down, with an
external spring to regulate chain tension:
<http://www.reneherse.com/images/DSCN00037.JPG>
What I can't figure out is how it shifts. The cable appears to ether
loop around or pass through the derailleur pivot and then wrap around
the shifter:
<http://www.reneherse.com/images/DSCN00138.JPG>
I assume that the copper-colored bit on the shifter serves to anchor
the cable somehow, but I can't figure out how this mechanism moves the
derailleur in and out. I realize that this sort of equipment is old
enough to be outside many posters' experience as well as far too modern
for Carl Fogel's reading materials to be of any use, but hopefully
someone can satisfy my curiosity.
carl...@comcast.net
Dear Steve,
It's a Cyclo Standard rear derailleur. Here's a diagram (figure 8.32)
and text from Berto's "Dancing Chain" 2nd edition p. 155:
http://i12.tinypic.com/4umulhl.jpg
Click on the lower right in Explorer for full size.
Briefly, it works like a huge screw with a very gentle thread. As the
two-wire model turns, it moves in or out on a gentle spiral groove in
the post.
No, you can't see the innards in the picture or diagram, which is why
it's so mysterious.
Compare it to the later Cyclo Touriste on the same page to get an idea
of how the whole jockey assembly moves in and out.
Cheers,
Carl Fogel
M-gineering
There is a course thread on the axle, turning the barrel moves the
jockeywheels to line up with the next cog
--
---
Marten
carl...@comcast.net
Here's a page with links to various Cyclo Standard models:
http://members.aol.com/SatoruMas/brands/cyclo.html
When you click on a model, don't stop at the first picture that you
see--you can usually page down to see more details.
CF
Steve Gravrock
> On Sat, 5 May 2007 20:20:14 +0000 (UTC), Steve Gravrock
><use...@sdg.users.panix.com> wrote:
>><http://www.reneherse.com/ReneHerse1950large.html>
[...]
> It's a Cyclo Standard rear derailleur. Here's a diagram (figure 8.32)
> and text from Berto's "Dancing Chain" 2nd edition p. 155:
>
> http://i12.tinypic.com/4umulhl.jpg
>
> Click on the lower right in Explorer for full size.
>
> Briefly, it works like a huge screw with a very gentle thread. As the
> two-wire model turns, it moves in or out on a gentle spiral groove in
> the post.
Thanks. That clears it up.
Although the details of the mechanism differ, the Cyclo design bears a
certain family resemblance to current Avid mechanical disc brakes.
Tim McNamara
Steve Gravrock <use...@sdg.users.panix.com> wrote:
The Cyclo derailleur used a continuous shifting cable, as you note, with
both ends fastening to the shift lever. This was necessary as there was
no return spring on the derailleur, which allowed for a very light touch
when shifting and the derailleur would self-center over the gear.
"Autoshifting" under load was reportedly absent in these derailleurs
because there was no spring pulling the derailleur towards the smallest
or largest cog. Also note the 180 degree chain wrap and compare that to
the Campy Nuovo Record chain wrap of 120 degrees or less.
The derailleur pivots on a pilot shaft with a helical slot; the cable
turns a hollow shaft that rides on the pilot shaft, moving the
derailleur in or out and shifting the gear. These were two, three or
four cog systems with a fairly limited range. Two or three chain rings
were often used with a difference of 20-25 teeth not being uncommon
(according to Frank Berto's book, you could get a 24-52 chainring
combination).
These derailleurs were reportedly real bastards to set up properly.
There were versions in steel and in alloy, the alloy derailleurs being
lighter than those available today (not taking into account the huge
chainstay mount, of course!). Because of the external chain tension
spring, the range of these derailleurs for chainring differences was
very large, but the range for freewheel cog differences was small.
The Cyclo was manufactured without significant changes in design from
1939 into the 1950s, with some people still ordering them on their Alex
Singers and Rene Herses in the 1960s.
A Muzi
If you have ever used a pre-cable front changer, it's the same
mechanism. A coarse helix moves the changer across the range when the
driving pulley is turned. That helix is usually either squared or
flatted so the piece moves laterally without turning. You can see the
front on one of the photos but not much detail. There are various cable
anchor versions; I don't know this specific setup but there's likely a
simple knarp in the system (no wire 'head').
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
carl...@comcast.net
wrote:
Dear Andrew,
Knarp? What the--
I'll be damned!
Knarp!
It really is a word, not a typo. I just googled the archives and was
gratified to find that this was its first appearance on RBT.
Knarp!
My ignorance plumbs new depths, but rarely with such a satisfying
splash. So that's what you call that kind of a doohickey!
Anyone as ignorant as I am can page down here for a picture:
http://www.mopedriders.com/viewtopic.php?p=50602
Here's a chaknce for everyokne to aknknouknce that they knew what a
knarp was all alokng.
Me, I'm going to spring it on a motorcycle mechanic who's a friend and
former English teacher and see what happens.
"Knarp" would be a good name for a dog.
Cheers,
Carl Fogel
Ryan Cousineau
carl...@comcast.net wrote:
Well, I did do a degree in English...Sheldon also knows this word:
http://sheldonbrown.com/harris/cables.html
The BRH19 Odyssey Cable Knarps, useful bodges for recreating the
now-obscure Raleigh double-ended brake cable. Yes, there's a picture.
> Me, I'm going to spring it on a motorcycle mechanic who's a friend and
> former English teacher and see what happens.
>
> "Knarp" would be a good name for a dog.
I sometimes call mine "Yarpy."
--
Ryan Cousineau rcou...@sfu.ca http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos
A Muzi
>>> <http://www.reneherse.com/ReneHerse1950large.html>
>>> I'm a bit puzzled by the rear derailleur. It seems to be a simple
>>> plunger type, which moves in and out but not up and down, with an
>>> external spring to regulate chain tension:
>>> <http://www.reneherse.com/images/DSCN00037.JPG>
>>>
>>> What I can't figure out is how it shifts. The cable appears to ether
>>> loop around or pass through the derailleur pivot and then wrap around
>>> the shifter:
>>>
>>> <http://www.reneherse.com/images/DSCN00138.JPG>
>>>
>>> I assume that the copper-colored bit on the shifter serves to anchor
>>> the cable somehow, but I can't figure out how this mechanism moves the
>>> derailleur in and out. I realize that this sort of equipment is old
>>> enough to be outside many posters' experience as well as far too modern
>>> for Carl Fogel's reading materials to be of any use, but hopefully
>>> someone can satisfy my curiosity.
>> Steve Gravrock wrote:
> A Muzi <a...@yellowjersey.org> wrote:
>> If you have ever used a pre-cable front changer, it's the same
>> mechanism. A coarse helix moves the changer across the range when the
>> driving pulley is turned. That helix is usually either squared or
>> flatted so the piece moves laterally without turning. You can see the
>> front on one of the photos but not much detail. There are various cable
>> anchor versions; I don't know this specific setup but there's likely a
>> simple knarp in the system (no wire 'head').
carl...@comcast.net wrote:
> Knarp? What the--
> I'll be damned!
> Knarp!
> It really is a word, not a typo. I just googled the archives and was
> gratified to find that this was its first appearance on RBT.
> Knarp!
> My ignorance plumbs new depths, but rarely with such a satisfying
> splash. So that's what you call that kind of a doohickey!
> Anyone as ignorant as I am can page down here for a picture:
>
> http://www.mopedriders.com/viewtopic.php?p=50602
>
> Here's a chaknce for everyokne to aknknouknce that they knew what a
> knarp was all alokng.
> Me, I'm going to spring it on a motorcycle mechanic who's a friend and
> former English teacher and see what happens.
> "Knarp" would be a good name for a dog.
I admit we get a larger share of 'weird' than many service shops but we
use a lot* of knarps here.
*couple dozen a year