Author Topic: Vintage derailleur query  (Read 1667 times)

jimmer

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Vintage derailleur query
« on: June 28, 2012, 10:34:16 pm »
Dear All,

I'm a little chary about posting this on the forum; it relates to Thorns only in that it is about a steel framed bike, being lovingly ministered to by a bona fide Thornie.

I've offered to spruce up my neighbour's Motobecane Profil 2 framed bike as a parting gift for his naive emigration from Brum to Oz in the misguided pursuit of a better standard of life.

He's a gas fitter who works to a scrupulously high degree of professionalism and has an unforgivingly sharp eye for the quality of work. The hand over will be a nervy affair as it is, without the following problem preventing completion of the job to the standard I would aspire to work at.

The quadrant, around which the shifter cable runs above rear derailleur, has been quite badly misshapen (in a fall I presume, the frame is still in alignment). I have bent it back into shape as best I can and the full range of gears are available but I don't think it will withstand shifting under pressure, the cable is likely to slip from the guide groove running around the outer edge.

Are replacement cable guides available or will a new derailleur be required?

Replacement is difficult as there is no cable stop on the chain stay to allow fitting of a regular derailleur. A bare gear cable runs from the shifter to the derailleur along the top of the chainstay.

The net has been well and truly, but fruitlessly, trawled for solutions.

That the bike belonged to my neighbour's deceased father may explain why I am willing to risk opprobrium by making this request of the throbbing collective Thorn consciousness.

At the risk of deepening your contempt for my audacious usurping of the forum's purpose; in this instance, authenticity can be sacrificed to efficacy.

Yours, with thanks, James
« Last Edit: June 28, 2012, 10:40:18 pm by jimmer »
 

Danneaux

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Re: Vintage derailleur query
« Reply #1 on: June 28, 2012, 10:45:40 pm »
Hi Jim!

'T'were me, I would head over to ebay.co.uk and take a look at this page, here...
http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p5197.m570.l1313&_nkw=chainstay+cable+stop&_sacat=See-All-Categories
(scroll down the page)...wherein the vintage, clamp-on chainstay derailleur cable stops are listed.

Older bike shops will surely have similar in stock, though likely in the parts bin from days gone by.

I'd get one and fit it forthwith, replacing the channelled guide presently in use with a section of conventional derailleur housing and a new cable to match. If the rest of the derailleur looks fine (and the cage is aligned parallel to the freewheel/cassette and the parallelogram looks sound), then I think this will resolve your dilemma, leaving a functional and reliable derailleur.

I've had good success doing this myself on a similar setup with great success. Unless there are other issues I've missed, this should fix things right up, and for a minimum investment in time, effort and coin.

Best,

Dan.

jimmer

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Re: Vintage derailleur query
« Reply #2 on: June 28, 2012, 10:56:06 pm »
Dear Dan,

Many thanks, you ruddy marvel.

Global Moderator, my *rse. Global Brain more like.

I had an inkling that you may have the solution to this one and was hoping to catch you before your tour.

E-Bay gum, here I come; as they probably give you a shoeing for saying in Yorkshire.

Yours, James