1981 Lady Galaxy rear brake problem

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wjhall
Posts: 65
Joined: 1 Sep 2014, 8:46am

1981 Lady Galaxy rear brake problem

Postby wjhall » 14 Jan 2017, 8:05pm

Problem:
I have just taken my wife's 1981 Dawes Lady Galaxy out of store with a view to recommissioning it for someone else to use. It has been relatively little used, so is in essentially original condition, apart from a handlebar change, during which I must have fitted a new inner wire. It is the smallest frame size, probably 19 inch, and a half twin lateral.

The main problem is the rear brake, which was not engaging with the rim, and I suspect may never have done so very firmly; we had low expectations of braking in the 1980s.

The rear brake is a Weinmann centre pull with the brake wire fed up the back of the seat tube from a cable stop about two thirds of the way up, over the pulley in a Mafac hanger on the seat tube clamp bolts, and so down to the straddle wire, the brakes being fitted on the seat stay cross piece. The hanger has a guide hole which is on the seat tube side, although it does seem to be possible to rotate it so that the hole would be on the brake side, but this does makes the clearance problem worse, and I think the current position is the ex-factory position.

The problem is that there is insufficient clearance between the straddle wire clip and the pulley, so that the clip was striking the pulley before the blocks reached the rim. I have adjusted the clip position slightly and turned it over to prevent the bolt fouling, so that the blocks do just reach the rim before this happens, and provide braking effort. There is nevertheless very little clearance left to accommodate brake pad wear. The straddle wires have a brazed on nipple at each end so cannot be adjusted.

I think this is a fundamental design fault arising from the traditional method of designing small frames by merely reducing the seat tube length, and that some other arrangement with more clearance should have been adopted for the rear brake on the smallest size. We have two other 1980s ladies tourers in similar sizes, a Raleigh trapezoid frame which uses a centre pull with the operating wire entry from below, and a Claud Butler with a full twin lateral, the brakes on a cross piece on the twin lateral and adequate clearance for a long straddle wire in between the twin lateral tubes. It is the failure of the latter's frame that has lead to the Galaxy coming out of storage for use as a spare to the Raleigh.

Questions:

1. Have I misunderstood anything?

2. Are there easy modifications, for example, replacing the pulley hanger with a short cable hanger and introducing a cable housing from the seat tube stop to create more clearance for straddle wire movement, or copying the side pull arrangement used on the Raleigh? I suspect that the existing stop is too high to give a natural routing for that. If so, what are the pitfalls to be avoided?
The current hangar has about 28 mm pulley pivot centre to clamp bolt centre spacing.

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: 1981 Lady Galaxy rear brake problem

Postby Brucey » 14 Jan 2017, 8:30pm

the easiest way of lowering the straddle and thus making clearance would be to install new (thicker) brake blocks and/or pack out the extant ones between the brake block and the brake arm, so that the caliper is wider open when the brake is on. Brake blocks meant for 'V' brakes may allow more adjustment in this respect

Other approaches might include

- making a shorter straddle wire
- if the caliper is mounted on curved washers, adjusting the angle of the caliper so that the bottom of the arms are as far forwards as possible
- fitting a clamp to the seat pin above the seat lug, and suspending the pulley from that
- using a different style of yoke, that is shorter (can't think of one offhand, mind)
- fitting a MAFAC brake (with an adjustable straddle wire)
- using a different hanger without a pulley, eg using a modified V-pipe to make the tight turn.

hth

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

wjhall
Posts: 65
Joined: 1 Sep 2014, 8:46am

Re: 1981 Lady Galaxy rear brake problem

Postby wjhall » 14 Jan 2017, 9:29pm

the easiest way of lowering the straddle and thus making clearance would be to install new (thicker) brake blocks and/or pack out the extant ones between the brake block a....
....
.... using a modified V-pipe to make the tight turn.


Thank you, I can see all those as being feasible, I will probably try packing out the brake blocks first. I already have some V-brake type brake blocks, and strange to say, also a pair of Mafac brakes, but after packing out the brake blocks I think I would then try a clamp above the seat, although the idea of making a shorter yoke did just cross my mind, it is only a piece of bent 1.6 mm steel.

tim-b
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Joined: 10 Oct 2009, 8:20am

Re: 1981 Lady Galaxy rear brake problem

Postby tim-b » 15 Jan 2017, 6:50am

Hi
If you're not too concerned about authenticity then consider a period side pull brake in place of the rear centre pull.
Swap the cable pinch bolt so that it's on the upper of the two caliper arms, and run the brake outer to the appropriate side of the seat tube and entering the brake from underneath.
New brake blocks might be an idea, my originals had hardened to the point of being useless.
Regards
tim-b
~~~~¯\(ツ)/¯~~~~

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speedsixdave
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Location: Nottingham, UK

Re: 1981 Lady Galaxy rear brake problem

Postby speedsixdave » 15 Jan 2017, 10:29am

And if you're really not concerned about authenticity, you could fit a modern Brompton dual-pivot rear brake which is designed to have the cable approach from below. I have fitted one of these on my wife's new open frame Bob Jackson and it works rather well.

The only problem with these is a lack of adjuster and quick release. If that bothers you you can buy an in-line qr and adjuster.
Big wheels good, small wheels better.
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rjb
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Re: 1981 Lady Galaxy rear brake problem

Postby rjb » 15 Jan 2017, 1:21pm

the weinmann cp brakes have various sizes of straddle wire. If you can find a short one this may be all you need.

robgul wrote:If any Weinmann centre pull enthusiasts are looking for brand new straddle wires - PM me - I have a bag that I'm taking to sell at a cycle jumble . . .

Rob


may be worth contacting rob in case he has any left, this post is fairly recent BTW. :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

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Gattonero
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Re: 1981 Lady Galaxy rear brake problem

Postby Gattonero » 16 Jan 2017, 2:03pm

speedsixdave wrote:And if you're really not concerned about authenticity, you could fit a modern Brompton dual-pivot rear brake which is designed to have the cable approach from below. I have fitted one of these on my wife's new open frame Bob Jackson and it works rather well.

The only problem with these is a lack of adjuster and quick release. If that bothers you you can buy an in-line qr and adjuster.


That sounds like the best option, as it will avoid the "S" bend of the brake cable.
Often is useful to put a ziptie around the seat-tube, leaving it a little slack, just to prevent the cable from moving around. And is reasonable neat.
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...

wjhall
Posts: 65
Joined: 1 Sep 2014, 8:46am

Re: 1981 Lady Galaxy rear brake problem

Postby wjhall » 17 Jan 2017, 12:23pm

Thanks for the further suggestions.

I have put in a pair of V-Brake blocks, which have a 10 mm spacer behind them, creating an extra 10 mm available pull on the brake wire. The simplest solution. There was actually more wear on the original brake blocks than I realised, they had lost about half, or 5 mm, so possibly just fitting new blocks would have recreated contact, I suspect that would have been the obvious solution if they had been more obviously worn, but still think that the margins in the original design were inadequate. The new brake blocks probably only have about 5 mm wear designed into them, but we now have modern, long, curved brake blocks. I suppose I ought to think about upgrading the front.

I had occasionally thought that there was no obvious reason why V-brake blocks could not go into Weinmann brakes, with Brucey's imprimatur I assume there is no reason not to use them. The curvature allows longer blocks with reduced risk of wearing into the tyre.

If I wanted to adapt further I think I would make a new hanger. Once you have found a 20 mm pulley it is only either a fairly simple U shaped piece of bent metal, or two pieces with a solid spacer.

Authenticity is nice, but not if it:

1. Costs money
2. Reduces braking power
3. Uses higher gears

Modernity is also nice, but not if it:

1. Costs more than GBP 35.

So I expect the Galaxy will acquire the triple chainset retrofitted to the failed Claud Butler.