Old 1/8” gear mech

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KM2
Posts: 407
Joined: 23 Oct 2008, 5:38pm

Old 1/8” gear mech

Postby KM2 » 11 Sep 2019, 6:09pm

Is there a rear gear mechanism which slides on a bar under the chainstay for a 3 cog 1/8” freewheel? Twin wire.
I guess 1940/50’s.

rjb
Posts: 3488
Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Old 1/8” gear mech

Postby rjb » 11 Sep 2019, 7:30pm

Doing a Google image search shows lots of possibilities.
https://www.google.com/search?q=1940s+d ... 0&bih=1024 :wink:
At the last count:- Focus Variado, Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin, Raleigh 20, Falcon K2 MTB dropped bar tourer, Longstaff trike conversion on a Falcon corsa. :D

iandriver
Posts: 2189
Joined: 10 Jun 2009, 2:09pm
Location: Cambridge.

Re: Old 1/8” gear mech

Postby iandriver » 11 Sep 2019, 8:06pm

Don't know about twin wire, but it sounds like an Osgear Super Champion. No jockey wheels etc, something like a movable tuning fork?
Supporter of the A10 corridor cycling campaign serving Royston to Cambridge http://a10corridorcycle.com. Never knew gardening secateurs were an essential part of the on bike tool kit until I took up campaigning.....

Brucey
Posts: 36060
Joined: 4 Jan 2012, 6:25pm

Re: Old 1/8” gear mech

Postby Brucey » 11 Sep 2019, 8:31pm

quite a few older mechs here

http://www.disraeligears.co.uk

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

amediasatex
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Joined: 2 Nov 2015, 12:51pm
Location: Sunny Devon! just East of the Moor

Re: Old 1/8” gear mech

Postby amediasatex » 11 Sep 2019, 8:51pm

Your description sounds a bit like a (French) Cyclo derailleur with desmodromic actuation.

Or possibly a very old Simpkex, depends what you mean exactly by ‘bar under chainstay’ And whether you’re talking about the mount or the mechanism.

KM2
Posts: 407
Joined: 23 Oct 2008, 5:38pm

Re: Old 1/8” gear mech

Postby KM2 » 11 Sep 2019, 9:20pm

The twin wire moved a vee shaped system which pushed the jockey wheels along a bar, so the jockey wheel moved the chain across the sprockets.

KM2
Posts: 407
Joined: 23 Oct 2008, 5:38pm

Re: Old 1/8” gear mech

Postby KM2 » 11 Sep 2019, 9:25pm

Bit like the French Cyclo, from the pictures, but not. External tension spring

Mike Sales
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Joined: 7 Mar 2009, 3:31pm

Re: Old 1/8” gear mech

Postby Mike Sales » 11 Sep 2019, 9:37pm

KM2 wrote:Is there a rear gear mechanism which slides on a bar under the chainstay for a 3 cog 1/8” freewheel? Twin wire.
I guess 1940/50’s.


There is all you might want to know about old derailleurs and their development in this book, which is also available as a pdf.

http://www.cyclepublishing.com/cyclingbooks/dc.html

https://all-med.net/pdf/the-dancing-chain/

Brucey
Posts: 36060
Joined: 4 Jan 2012, 6:25pm

Re: Old 1/8” gear mech

Postby Brucey » 11 Sep 2019, 10:06pm

the cyclo 'standard' derailleur (from 1932 onwards) used twin cable actuation

http://www.disraeligears.co.uk/Site/Cyclo_Standard_derailleur.html

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

amediasatex
Posts: 746
Joined: 2 Nov 2015, 12:51pm
Location: Sunny Devon! just East of the Moor

Re: Old 1/8” gear mech

Postby amediasatex » 12 Sep 2019, 8:43am

KM2 wrote:Bit like the French Cyclo, from the pictures, but not. External tension spring


Image

They do have external tension spring, you can see it above the actuation cable, running along under the chain stay and attached to the top of the cage.

Can you describe how then one you’re thinking of is different? Might help us pinpoint for you...

NetworkMan
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Joined: 25 Aug 2014, 11:13am
Location: South Devon

Re: Old 1/8” gear mech

Postby NetworkMan » 12 Sep 2019, 11:16am

They do have external tension spring, you can see it above the actuation cable, running along under the chain stay and attached to the top of the cage.

The Cyclo standard, in my old Pitman's Cycling Handbook, looks roughly similar but the Bowden cables both rise vertically up from the mechanism to be clamped to the seatstay. The book (first edition 1950, mine is third, 1960) says it's still in manufacture . Pulling on the cable rotates a pulley that then screws along a fixed shaft taking the rest of the gubbins with it.

Edit. Loads more in the book but apparently only Cyclo standard has twin wire actuation.

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Old 1/8” gear mech

Postby Brucey » 12 Sep 2019, 11:40am

cyclo standard (from Birmingham)

Image

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

9494arnold
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Joined: 21 Jan 2007, 3:13pm

Re: Old 1/8” gear mech

Postby 9494arnold » 12 Sep 2019, 11:54am

Trivelox ?

Afraid I don't have the technology to post images.

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Old 1/8” gear mech

Postby Brucey » 12 Sep 2019, 12:15pm

Image

the above is a 'bellcank' model, i.e. high normal. There were also 'pullchain' (low normal) models. Perhaps the most (in) famous trivelox gear was the sort that had a fixed position tensioner, and shuffled the sprockets from side to side to change gear. I don't remember seeing a twin-cable version though.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

NetworkMan
Posts: 715
Joined: 25 Aug 2014, 11:13am
Location: South Devon

Re: Old 1/8” gear mech

Postby NetworkMan » 12 Sep 2019, 12:42pm

Brucey wrote:cyclo standard (from Birmingham)

Image

cheers

Yup, that's the one in my book. In that picture the tension pulley is about 120 degrees round from where it would be in operation.
Seen any more with twin cables?