Sachs and Sturmey Archer Compatibility

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Invicta Tourist
Posts: 123
Joined: 19 Jul 2009, 10:18am

Sachs and Sturmey Archer Compatibility

Postby Invicta Tourist » 12 Feb 2019, 5:35pm

Does anyone know whether a Sturmey Archer toggle chain (HSA125) could successfully replace a Sachs Torpedo three speed coaster brake toggle chain? Do you have any information whether the threads are the same diameter at each end of the chain and would it be the right length? Thank you.

Brucey
Posts: 35553
Joined: 4 Jan 2012, 6:25pm

Re: Sachs and Sturmey Archer Compatibility

Postby Brucey » 12 Feb 2019, 6:13pm

it is a yes, no, no type answer.

Yes you can usually use one but the threads are different; it is best if you remove the Sachs/Sram toggle key and replace it with (modified where necessary) SA item.

The Sachs/SRAM rodss vary and the SA rods come in about nine different lengths; probably it is best if you get one that is close in length and mark it so that it can be set as per the original rod.

Another alternative (if the chain is broken) is to rivet a SA chain to the SRAM end fittings.

NB because of the way these older hubs work, it is most important that the gear2 setting is accurate; the high and low gear settings have a bit more leeway in them.

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

rogerzilla
Posts: 1315
Joined: 9 Jun 2008, 8:06pm

Re: Sachs and Sturmey Archer Compatibility

Postby rogerzilla » 12 Feb 2019, 8:53pm

I would be on the lookout for NOS Sachs/SRAM spares, since SRAM stopped making or supporting IG hubs in 2017. The clutch keys tend to snap on the Torpedo and I would definitely buy those if you see them. FG 10,5 axle nuts are made by other people so should still be available. Still, be careful not to overtighten them as they are usually sacrificial and will let go before the axle threads, then you'll have to buy them from Germany. SA recommend 25Nm on the axle nuts but I find 20Nm to be quite sufficient. Ball bearings can be replaced in the old cages but NOS cages are worth buying if they come up.

I managed to get a brake cone for my Duomatic 102 just before they all sold out. Hopefully the hub will now last for ever!

Brucey
Posts: 35553
Joined: 4 Jan 2012, 6:25pm

Re: Sachs and Sturmey Archer Compatibility

Postby Brucey » 13 Feb 2019, 1:06am

they were still making hubs in 2017 but had announced that they would stop. I don't know exactly when they actually stopped but it was either very late 2017 or very early 2018.

Currently there is no money to be made in cheap 3s hubs; judging from the cost of the things and the price differentials that exist for models of 3s hubs, you ought to be able to buy OEM 3s hubs kits (i.e. including the shifter and cable as well as the hub itself) as a bike manufacturer for about ten quid, maybe a touch more. I wouldn't like to make a hub for that money!

BTW there have always been a few pattern spares available for SA and Sachs hubs, like control toggles and shifters. I wonder if they will carry on being made...?

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

Invicta Tourist
Posts: 123
Joined: 19 Jul 2009, 10:18am

Re: Sachs and Sturmey Archer Compatibility

Postby Invicta Tourist » 13 Feb 2019, 4:09pm

Thank you for your replies Brucey and Rogerzilla. It's helpful to know that the SA threads would not be compatible with the ones currently existing on the Sachs Torpedo hub.
You're right, Brucey, the toggle chain has broken, it snapped at the point where the toggle chain leaves the hollow end of the axle nut. I bought a replacement Sachs toggle chain from the internet, but found that although it screwed into the hub OK, the part where the end of the toggle chain joins to the connector is too large a diameter thread. I joined the two parts with a piece of wire and, although I can access all three gears, prefer to leave it in second, as the wire is not very strong.
Brucey, you mention that it may still be possible to buy pattern parts for Sachs hubs. Do you know where I could buy one like toggle chain shown in the photos? I have searched the net, but we may be using different search terms.
Image Attachments
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Brucey
Posts: 35553
Joined: 4 Jan 2012, 6:25pm

Re: Sachs and Sturmey Archer Compatibility

Postby Brucey » 13 Feb 2019, 4:34pm

your new toggle chain is not designed to couple via a screw thread; it is intended to be used with spring loaded anchorage.

https://www.sjscycles.co.uk/hub-spares/brompton-gear-cable-anchorage-sram/

it wouldn't be very difficult to rivet or weld the new chain to the old adjuster, so maybe you could do that.

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

Invicta Tourist
Posts: 123
Joined: 19 Jul 2009, 10:18am

Re: Sachs and Sturmey Archer Compatibility

Postby Invicta Tourist » 13 Feb 2019, 8:01pm

I'll look into how to do rivetting. It is probably quite a useful skill to have. :)

Brucey
Posts: 35553
Joined: 4 Jan 2012, 6:25pm

Re: Sachs and Sturmey Archer Compatibility

Postby Brucey » 13 Feb 2019, 10:14pm

If you have some basic tools and a load of bicycle parts it is easy enough to rivet this sort of chain using a short length of old galvanised 14G spoke as a rivet. Just drill the holes out to 2mm, insert the 'rivet' and peen the ends over with a little light hammering. It doesn't matter much if the riveted joint onto either solid endpiece doesn't articulate freely; if these joints need to articulate freely then there is something wrong with the installation.

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

Invicta Tourist
Posts: 123
Joined: 19 Jul 2009, 10:18am

Re: Sachs and Sturmey Archer Compatibility

Postby Invicta Tourist » 14 Feb 2019, 4:54pm

Thank you for the useful idea, Brucey. I started looking on the net to find a beginner's guide to riveting and came across this useful clip on YouTube. https://youtu.be/cP14SBqvpYM I believe using this riveting technique for the ends of the toggle chain with two pieces of a 14g spoke, as you suggested, should solve the problem.

Brucey
Posts: 35553
Joined: 4 Jan 2012, 6:25pm

Re: Sachs and Sturmey Archer Compatibility

Postby Brucey » 14 Feb 2019, 5:02pm

surely you only need one rivet, to join the new rod and chain to the old adjuster section?

Image

shows a remanufactured FW control rod; you can see a conventional 3s chain and adjuster has been riveted onto a newly made rod assembly; in the case the 'odd rivet' is at the other end of the chain.

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

Invicta Tourist
Posts: 123
Joined: 19 Jul 2009, 10:18am

Re: Sachs and Sturmey Archer Compatibility

Postby Invicta Tourist » 14 Feb 2019, 5:30pm

I'll check but I'm pretty sure the new toggle chain is slightly longer then the original. I've needed to move the rear wheel backwards to the furthest extent of the dropouts and add two new drive chain links.

I see what you mean. What I could do is use the new indicator rod and shorten its toggle chain by removing a few rivets, then rivet this to the old connector, having checked that the newly made and old toggle chains have approx the same overall length.