What this chainstay braze-on is for ?

General cycling advice ( NOT technical ! )
RobC
Posts: 106
Joined: 5 Feb 2008, 3:27pm

What this chainstay braze-on is for ?

Postby RobC » 21 Jun 2020, 12:32pm

This is on the underside of the RH chainstay on the frame of a 1930s FH Grubb tandem frame. Frame is upside down in the pic.

It has a rod-operated rear drum brake but that is routed along the other side obviously, so I don’t think it’s anything to do with that.

I half thought it might be something to do with an old chainguard but very much doubt this tandem was ever equipped with one.

(Yes I know the rings are very worn!)
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Jdsk
Posts: 784
Joined: 5 Mar 2019, 5:42pm

Re: What this chainstay braze-on is for ?

Postby Jdsk » 21 Jun 2020, 1:41pm

Is there another clip about a spoke's length away?

Jonathan

RobC
Posts: 106
Joined: 5 Feb 2008, 3:27pm

Re: What this chainstay braze-on is for ?

Postby RobC » 21 Jun 2020, 2:13pm

Nope!

Jamesh
Posts: 1269
Joined: 2 Jan 2017, 5:56pm

Re: What this chainstay braze-on is for ?

Postby Jamesh » 21 Jun 2020, 2:19pm

I think it's probably designed to thread di wiring through.....

:lol: :lol: :lol:

Cheers James

Marcus Aurelius
Posts: 1504
Joined: 1 Feb 2018, 10:20am

Re: What this chainstay braze-on is for ?

Postby Marcus Aurelius » 21 Jun 2020, 3:30pm

It looks like an anchor point for a chain ring guard.

tatanab
Posts: 4081
Joined: 8 Feb 2007, 12:37pm

Re: What this chainstay braze-on is for ?

Postby tatanab » 21 Jun 2020, 3:47pm

Given the age of the frame I would say it is for one end of the spring on a Trivelox rear gear. See the video on this link http://www.classicrendezvous.com/Britis ... ivelox.htm

RobC
Posts: 106
Joined: 5 Feb 2008, 3:27pm

Re: What this chainstay braze-on is for ?

Postby RobC » 21 Jun 2020, 4:06pm

Thanks for the ideas. It’s right at the bottom bracket end of the chainstay so I doubt it’s anything to do with a rear gear.

Not exactly the most pressing issue in the world but I’m just curious!

tatanab
Posts: 4081
Joined: 8 Feb 2007, 12:37pm

Re: What this chainstay braze-on is for ?

Postby tatanab » 21 Jun 2020, 4:19pm

Same video her plus some more info and you can see that the spring clearly goes all the way forward especially at about 47 seconds. https://www.youtube.com/watch?v=9SzzUuykBSw

Brucey
Posts: 39379
Joined: 4 Jan 2012, 6:25pm

Re: What this chainstay braze-on is for ?

Postby Brucey » 21 Jun 2020, 4:47pm

tatanab wrote:Given the age of the frame I would say it is for one end of the spring on a Trivelox rear gear.


+1

cheers
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thirdcrank
Posts: 28807
Joined: 9 Jan 2007, 2:44pm

Re: What this chainstay braze-on is for ?

Postby thirdcrank » 21 Jun 2020, 4:48pm

disraeli-brochure-conversion-kit.jpg


Well spotted tatanab. (I'm 75 and this was long before my time, I think.)

Brucey
Posts: 39379
Joined: 4 Jan 2012, 6:25pm

Re: What this chainstay braze-on is for ?

Postby Brucey » 21 Jun 2020, 4:57pm

For those that have never seen one, the Trivelox was a derailleur that preserved a perfect chainline; the guide pulley was in a fixed position, and the sprockets moved from side to side on a splined carrier when you changed gear. You can just see the end of the splined carrier in Thirdcrank's illustration.

There were at least two versions of the triVelox derailleur; one where the 'derailleur' used a 'blade' that sat between two of the sprockets and moved the sprockets from side to side

Image

and another where the sprockets were controlled using a toggle chain in the hub axle

Image

both used the 'long spring' (with optional bootlace or binder twine, etc etc). In later years the TriVelox name was used on more 'normal' derailleurs.

cheers
Last edited by Brucey on 21 Jun 2020, 5:11pm, edited 1 time in total.
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Grandad
Posts: 1163
Joined: 22 Nov 2007, 12:22am
Location: Kent

Re: What this chainstay braze-on is for ?

Postby Grandad » 21 Jun 2020, 9:59pm

I remember having a derailleur gear with a similar spring in the early 1950's. Can't remember the name though, certainly not TriVelox

RobC
Posts: 106
Joined: 5 Feb 2008, 3:27pm

Re: What this chainstay braze-on is for ?

Postby RobC » 21 Jun 2020, 11:19pm

tatanab wrote:Same video her plus some more info and you can see that the spring clearly goes all the way forward especially at about 47 seconds. https://www.youtube.com/watch?v=9SzzUuykBSw


I stand corrected! Thank you for enlightening me and apologies for poo pooing the idea. Thanks everyone for your thoughts, mystery solved.

RobC
Posts: 106
Joined: 5 Feb 2008, 3:27pm

Re: What this chainstay braze-on is for ?

Postby RobC » 21 Jun 2020, 11:54pm

Grandad wrote:I remember having a derailleur gear with a similar spring in the early 1950's. Can't remember the name though, certainly not TriVelox


From the serial number I know the frame is 1933 or 1934, and I’ve found this excerpt from the catalogue online which seems to be a good match. The original rear wheel is long disappeared as the current rear hub was “only” built in 1938. The gearing options in the 34 catalogue include two that are derailleurs, both by Cyclo. Would that have had the long spring..?

57D5A3FB-8024-4A81-92F0-C0A7F23A354D.gif