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The Auto-Mini and the Sachs Torpedo Duomatic | Wired Cola

The Auto-Mini and the Sachs Torpedo Duomatic

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ready to go.JPG folded.JPG
Having reassembled the Auto-Mini as a project for keith, I took it for a test ride today and was reminded of my one complaint about the machine: it managed to feel simultaneously overgeared and undergeared at various times. I assumed this was the miracle of being a heavy, clunky folding bike.

But today, I was giving it one last ride for fun, and I took a closer look at the rear hub. It's a Sachs Torpedo Duomatic. Eh? With a name like that, it has to be a multi-speed hub, right? But I had always discounted that idea because there was no shifting mechanism. But today I took a closer look, and watched the holes in the sprocket to see if they stayed aligned with the oil fitting on the hub. No! That meant it had to have internal gearing, for nerdy bike reasons.

Google to the rescue. It's a "kickback" hub. The shifting mechanism is a light backpedal, which pops it from one gear to the other. Remarkable, and suddenly much more functional. An exploded view.

It still doesn't fold very well, but at least it has two speeds.


I too have such a hub and am

I too have such a hub and am wondering of the maintanence and adjustibility of it.

The usual rule of thumb with

The usual rule of thumb with gearhubs of any type is that you're best off just leaving it alone. They require very little maintenance.I haven't had to investigate adjusting this hub, either, but from the exploded view, I'd say there's virtually no adjustment to be done.The biggest trick with 3-speed hubs is fiddling the shifting adjustment, and that's a non-issue with the Duomatic.

Your blog has saved my

Your blog has saved my Moulton (1962) with Sachs Torpedo dumatic hub, which I disassembled to clean the ancient grease and am having 'difficulty' putting it back together again.The link to Sachs has the diagram I require - Thanks!Now to transalte - I think there is something about grease and these hubs that is important.....

heres the translation:From

heres the translation:From 1966, the Fliehgewichte produced be pressed of a fine feather after interior and work out turns find are from ca 16-18km/h outward the hub thereforeautomatically in ca 16-18km/h between both gears around inconspicuously to see there no Schaltzug required relatively rarely and to distinguish external onlyat the inscription of the Duomatic an explosion drawing of the hub you here the translation ratios of the hub: 1. Gear 1:1 - 2. gear 1:1,362 (see alsotranslation table)Load report Automatic hubTo be sure I am was grants myself not proud owners of a so rare piece, it however in March 2000 to cycle with a so equipped "Omafiets" a half day long through Utrecht (NL). It is already astonishing how dependably and certainly the switch results, for me rather exactly at the point, at which I would have shifted also manually. Also the shifting results inconspicuously after one becomes slower and the pressure diminishes something on the pedals (example manner in the Zurollen on a red traffic light). An ideal control for dense urban stop-and-Go-traffic. Would damage that it was constructed only a few year long in so slight number of pieces.

This is hilarious. I thought

This is hilarious. I thought you all might want to knwo that this is one of my most consistently hit old web pages. I get nearly daily searchers looking for info on the Duomatic. The best part is that the comments here are making this page even more useful.Thanks!

Hi! Happy I found this blog.

Hi! Happy I found this blog. Really cool. I'm the proud owner of a Auto-Mini in really good condition. It's white and features a Duomatic hub. It still has it's original 70´s white wall tires. I'll post some pics of it as soon as I've made some. I also have a Torpedo Automatic hub, almost unused. I'm wondering if the hub shells for those two hubs are the same? If it is, I'll try the bike with the Automatic too. Does it get any nerdier? See you around! Pär B, Gothenburg Sweden

Anyone have any info an

Anyone have any info an Torpedo Duomatic axel nuts? Mine is some wierd pitch/thread combo that according to the genius at Colorado Metric Fastener "Does not exist". I have this really cool wheel and no way to attach it to my bike... help!

Subliminalshiver:Was the


Was the problem that you talked to a metric fastener guy instead of a bike guy? The canonical thread pitches for axles are 1 mm or 26 tpi. The Sachs is probably 26 tpi, that being both non-metric and the common Campy standard of the era.

I bet you one of these nuts are the ones you need. Maybe 10mm x 26 tpi? There are other possibilities, but you should be able to measure the axle diameter with ease.

If still in doubt, an imperial thread gauge is a pretty cheap tool to get some peace of mind.

Hm...this page on the Duomatic (same guy who gave us the priceless exploded diagram) has a pair of photos of the top. I don't speak German, but if those captions don't say "model with 9.5 mm axle" and "model with 10 mm axle", I'll eat my Campy hat.

More details in the footnotes, and this time translated via Google:

"it gave in two versions: old version with flattened axle (10,5mm diameter similar to torpedo Three-course hubs), newer version with round axle (9,5mm diameter similar to resignation hubs without circuit)"

So there you go. You just have to figure out if you have the newer version, similar to resignation hubs without circuit.

Joking aside, I think that last phrase means something like "...similar to common hubs without gears."

The earlier 10.5 mm axles may be a bit unusual, but the nuts for the 9.5 mm axle should be quite common. Try Loosescrews.com or the QBP catalog.

The Duomatic hub is

The Duomatic hub is back:


Also details about the F&S Torpedo Automatic hub (for 20" up to 24" wheels) which has not the backpedal inconvenience.

Gruß Marco

Sturmey Archer nuts for Sachs duomatic

This is to confirm for others that I have successfully put a Sturmey Archer nut onto the Sachs 10.5mm axle, it is a little tighter than the Sachs one because it's an Fg 10.3 rather than Fg 10.5 thread (Fg is a German standard for bike threads, Fahrad gewinde). It still went on with only fingers, so it isn't much smaller when you consider manufacturing tolerances (allowable variations), but it is definitely a little more snug fit as I predicted in an earlier message.

So if you have a slightly worn axle on any Sachs gear hub this will prolong its life rather than finding a new axle. Being nerdy can be very useful! Do you hear that ladies?

Unfortunately the Sturmey Archer anti rotation washers (HMW494 or 155) don't fit onto the axle as bought, but a few minutes of filing of both the flats and the rounded ends of the hole with a rat tail file made one fit very nicely.

Henry in Oz



Thanks for the incredibly helpful info on the Sturmey-Archer axles and nuts. This is the first place I was able to find the ACTUAL size and TPI (13/32" by 26 TPI) of the axle and nut for a S-A hub. You wouldn't think this should be secret information, but no online vendors include that info on their websites.

Tim in New Mexico

Don't thank me...

Thank the commenters!

Auto Mini

Hey everyone, I picked up a Junior Auto Mini last week and I am going nuts trying to get more info on them (no Wikipedia page???) does anyone know what year they were manufactured? I heard something about 82' but I'm not sure how accurate the source is. Thanks in advance!

Auto Mini age


Info is indeed sparse, but components often date any bicycle more accurately than the frame's brand name (because component changes from year-to-year are relatively well-documented, the type of hub or brake or derailer on a bike can give a fine-grained idea of the bike's age).

That said, the web pages I have read suggest the Auto-Minis tend to be early-70s bikes, and the components themselves (at least on my bike) suggests a late-60s early-70s age.

The Torpedo Duomatic hub, in particular, suggests my bike is no later than 1970, as I believe it has a 1st-gen hub.

1982 is a possible age, but unlikely: I don't think the Auto-Minis were likely to have had a 10-year run.

When you say yours is a Junior, what size are the wheels?

I, too, have an ancient Duomatic... maintenance instructions


I randomly found this site when looking up information for 3-speeds. But it so happens that I also have a 2-speed Duomatic I can tell you all about. I am studying in Sweden right now, and a friend of mine found this lovely old Danish SCO brand bike in a field. I fixed up the bike to decent condition, the only tricky part was of course getting this hub to work nicely again. I think the bike was from the early 70's, it has 650A wheels, cottered cranks, and Olympic branding (an obvious '72 I imagine). SCO bikes are quality, great lugged frame construction and beautiful metallic hunter green paint.
Of "wow times have changed" note, the label on the bike states an incredible 10-year warranty, totally insane in this day and age!

I had some trouble pulling the hub apart, but an axle vise helps. I got the entire thing apart and cleaned everything out. The grease had turned almost into mastic, it was very sticky and slow, making shifting unreliable and rolling rough. Clean it with a light solvent. Pack the bearings at each end with grease. Very liberally apply a light machine oil to the gear mechanism, and then pack the coaster brake area with as much grease as possible (high heat tolerance, if you can find it). Coaster brakes are terrible, but they are a lot less terrible when they are well lubricated.
The brake shoes are probably the only part of these hubs that really do wear out. So regardless of being well lubricated, they still totally suck at stopping, *especially* downhill. Make sure you at least have a handbrake on the front!!

Don't be afraid of taking the hub apart (the same method goes for 3 speeds as well). Unless you start pulling apart the gearing mechanism (which is hard to do) you can't do any harm. And even then... you can figure it out. Getting the right compression when you put the hub back together is easy too. They are not high-precision devices. If it spins freely with no bearing friction, it's fine.

As far as the axle nut, I had that problem as well. One of my local bike mechanics managed to find a nut that fit okay, though it is a little on the loose side. Took him a few minutes, but he found it.

All in all it rides very well now. It certainly makes for a nice vintage bike when you can use all of the original parts, especially when the wheels are an antiquated size. It's certainly not a Nexus but it's a nice cruise.

Almost forgot: Disintegrating bearings

I almost forgot to write this. If you take apart your hub, take a look at the bearing ring on the the brake (left) side of the hub. The bearings on this side tend to disintegrate faster. If they look a little worse for wear (after you get all the gunk off), seriously consider popping them out of the ring and finding replacements at a machine shop/hardware store. Bearings that disintegrate spew shards of metal that dig into the bearing cup, making even smooth pavement feel like you're riding on gravel. You can replace bearings, but you can't replace the hub!!

Have an auto-mini junior i'd like to sell..

I am looking to sell an auto-mini that i picked up at a garage sale. could anyone tell me what the value of one of these bad boys are worth. Internet info is very scarce and i'm not much of a bike collector to know in detail about part dating. Would be great to get an idea of what they would be worth. Thanks anyone.


The collectible value of any Auto-mini is moderate to low. Since their reputation is that of a fragile imitation of a Raleigh Twenty, you can assume the sorts of values that implies.

Without claiming to be an expert, I'd say that a very nice Auto-mini is worth less than $100.

If your Junior has a 3-speed Sturmey-Archer hub, then dating it will be fairly easy: S-A always stamped the year into its hubs. You should see a two-digit year code (eg "68" for a made-in-1968 unit) stamped on the body of the hub.


I am interested in purchasing a sachs torpedo kickback hub. i am a fixed gear rider who has recently blown my knee out. i love to ride with the simplicity of a fixie but with the injury can no longer do that. If anyone has one willing to sell will you be willing to sell one. here's my email. please no spam. motoello@hotmail.com. send pictures if you have them

New Duomatic-like hubs!

Sunrace/Sturmey-Archer is about to start selling new Duomatic-type hubs! I don't know if it's a licensed copy of the original, an unlicensed clone, or a completely new design.

Duomatic stripdown in photographs

The whole hub is dismantled and rebuilt with all steps photographed on my website here:



Very interesting site.

Very interesting site. Greetings all from North Bay Ontario up in Canada. I have a CCM CHEETAH in my garage with serial number either A or a triangle 176625. Would it be better to part it out or sell it as a complete project. It has a great working Torpedo Duomatic 2 speed 28 spoke kickback hub.

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