Unusual ways to change gear, Bikelopnik edition

"bhtooefr" (bhtooefr) 01/27/2017 at 12:43 • Filed to: bikelopnik, transmissions, fichtel & sachs, sachs, torpedo, duomatic

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Because shifters are overrated.

So, this is the Fichtel & Sachs Torpedo Duomatic 102 hub, a kickback-shifting 2-speed internally geared hub with coaster brake, intended primarily for folding bicycles, from 1964.

Similar hubs are the Duomatic 101 (the same thing without the coaster brake), earlier Bendix 2-speed Automatic hubs from the 1960s, the later Torpedo Duomatic R 2110 from circa 1970, and the modern Sturmey-Archer S2C and S2K hubs. (There was also a fully automatic variant of the R 2110, known as the A 2110, which SRAM has reintroduced as the Automatix. Shimano had their own 2-speed automatic hub, the AB-100, in the 1970s as well. These, however, don’t have the kickback shift functionality, instead using flyweights to manipulate their ring gear pawls.)

The Torpedo Duomatics share a lot with the 3-speed Torpedos of the era, but have an entirely different shifting mechanism. So, in a normal 3-speed hub, like those made by Sturmey-Archer, the sun gear is fixed on the axle (which is bolted firmly to the frame, it’s not turning), and the planet carrier and ring gear can be connected alternately to the hub shell and the input driver. Low gear is formed by connecting the input driver to the ring gear, and the hub shell to the planet carrier, middle gear is formed by connecting both to the ring gear (bypassing the gearing entirely), and high gear is formed by connecting the input driver to the planet carrier, and the hub shell to the ring gear. A shift cable moves a clutch in and out to select the configuration.

In the Duomatics, low gear is unavailable - first gear is a direct drive, and second gear is the high gear. The planet gear is always connected to the hub shell through a set of pawls (I believe at the brake assembly), and the ring gear has pawls can be engaged to the hub shell through a driver ring as well. When this happens, the hub shell will overrun the planet gear and its pawls, causing the hub to click in high gear.

Engaging those ring gear pawls is where it gets a bit interesting, though. When you backpedal, a control ring is allowed to rotate, that control ring affecting whether the ring gear pawls are retracted or extended, either disconnecting it from, or connecting it to the hub shell. This means that no shifter is required, you simply backpedal and get the other gear. And, backpedal hard, and you get both a shift and braking, on models with a coaster brake.

Chariotoflove > bhtooefr 01/27/2017 at 12:54

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Index shifter, no derailleur required:

That was seriously hard to wrap my brain around. It’s gonna take some time.

TheRealBicycleBuck > bhtooefr 01/27/2017 at 12:54

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I used to own an old Schwinn which had a two-speed kickback hub with a coaster brake. That thing was fun for what it was, but I must admit that owning something with more than two gears and more than one brake is much better.

Thanks for posting the exploded diagram. I haven’t seen the innards of one of these hubs in a very long time.

S65 > bhtooefr 01/27/2017 at 13:02

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6/10 too complicated give me my shimano derailleur and v brakes back.

bhtooefr > TheRealBicycleBuck 01/27/2017 at 13:14

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The Bendix hubs that Schwinn used had a somewhat different shift mechanism (it actually reminds me a lot of the action of a clicky pen), but the same effect. (Well, not exactly - the more common red band and yellow band Bendix hubs were underdrive, instead of overdrive - so 1st was a low gear, 2nd was a direct drive. The blue band Bendix hubs were overdrive, though.)

I actually have an R 2110 on my Dahon Boardwalk - it had a single-speed coaster brake hub that wasn’t in great shape (only the finest of bottom-of-the-line Taiwanese engineering), and I wanted more gearing. I decided that it’d be easiest to stick with a coaster brake for the rear (it has a front V-brake), and I didn’t want a cable crossing the hinge, or external shifting components to get broken if it got banged around, so I decided on the Duomatic. With how I’ve got the gearing set up, 2nd gear is a slow cruise, 1st gear is for getting off the line and climbing.

facw > bhtooefr 01/27/2017 at 13:14

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Internally geared hubs are always scary to look at.

Highlander-Datsuns are Forever > bhtooefr 01/27/2017 at 13:14

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All that internal guts for 2 gears. Thats amazing and reminds me why I never tried to fix one beyond spraying penetrating oil into the guts.

bhtooefr > facw 01/27/2017 at 13:21

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And this one’s only a 2-speed. Go look at the Big Bad Zwölf if you really want nightmares: http://www.sheldonbrown.com/elan.html and http://www.sheldonbrown.com/elanratios.html

(IIRC, it’s actually a lot more complex than a Rohloff Speedhub, at least as far as what it’s doing (IIRC the Speedhub just uses more stages of gearing to get what it wants, which is conceptually easy to figure out), which is saying a lot .)

bhtooefr > Highlander-Datsuns are Forever 01/27/2017 at 13:23

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To be fair, a 3-speed wouldn’t really be any more complex - this is just a 2-speed because there’s not a great way to do a 3-speed kickback (although Sturmey-Archer has tried, actually).

bhtooefr > S65 01/27/2017 at 13:24

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Fuck derailleurs.

V-brakes, OTOH... I don’t hate them. (I don’t like them either, but I don’t hate them.) And, the bike that I have a Duomatic on also has a V-brake up front.

TheRealBicycleBuck > bhtooefr 01/27/2017 at 13:25

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Climbing. With two gears. Hah!

I’ve thought about trying out one of the new multi-speed hubs, but they don’t show up often in the bike shops around here and when they do, it’s usually on something I don’t want to ride.

What really fascinates me are the guys doing crazy gear combos on their recumbents. I saw one with a Rohloff in the back, a Schlumph crank in front, a front derailleur, and a mid-mounted rear derailleur. Tons of redundancy, but lots of choices!

Roadster Man > bhtooefr 01/27/2017 at 13:27

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We can all agree about Derailleurs, but oh baby I’ll take a nice set of Magura hydraulic rim brakes over disc brakes any day.

So nice!

Dave the car guy , still here > bhtooefr 01/27/2017 at 13:33

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I used to repair bikes for friends and I can recall taking one of those apart to work on the brake. Was a challenge to get back together on memory alone. Would rather it be a Bendix or Sturmey-Archer 3 speed with cable shift since I knew those a little. Sturmey-Archer makes a 2 speed kickback hub still and its pretty large so I’d hope the braking is better than some of the old school stuff.

PotbellyJoe and 42 others > S65 01/27/2017 at 13:38

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For ease of tuning, I have yet to find something better than SD V-brakes or BB mech discs.

For power, wear and everything else, well... there are better.

Neil drives a beetle and a fancy beetle > bhtooefr 01/27/2017 at 14:01

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I had a buddy who had a kickback. He was a strange but awesome guy. The kickback fit him, it’s a weird and cool system.

bhtooefr > TheRealBicycleBuck 01/27/2017 at 14:05

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Well, to be fair, I’m running a 48/22 into a 20" wheel, and first gear is direct drive. So, about 40.8 gear inches in 1st, and 55.5" in 2nd.

My recumbent trike has a Sturmey-Archer X-RF8(W), which is an extremely... brute-force way to get gearing - each stage’s ring gear feeds into the next stage’s planet carrier (with the sprocket driving the first stage’s planet carrier, and the third stage’s ring gear driving the hub), and you just lock different combinations of stages’ sun gears to the axle to get different gears. It’s horrifically noisy and inefficient in the higher gears - by the time you get to 5th, it starts sounding like a pack of bees, and 8th is about 84% efficient. I’ve got a 26.9 to 87.1" range right now, although the driveline isn’t fond of high torques (stupid chain routing decisions), and there’s horrific boom flex, so I can’t climb worth a damn with it.

My recumbent bike just has a 3x9 derailleur setup right now. 23.3" to 117.6" range. I just don’t like how derailleurs shift...

The insane IGH that I really want, though, is the NexxtDrive Gemini, whenever they actually release it... single planetary set, pedals are connected to the planet carrier, a generator is connected to the sun gear, and another motor and the hub shell are connected to the ring gear. If this sounds like a certain automotive transmission design, it should - it’s basically a Prius transmission, but scaled down to bicycle scale. They did add a one-way clutch, so that the sprocket cannot spin faster than the hub shell - this means that they don’t have to worry about starting torque being too high, and slipping the hub when the motors aren’t up to speed (because human power is far less even and predictable than engine power).

bhtooefr > Dave the car guy , still here 01/27/2017 at 14:09

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Those Sturmey-Archer kickback hubs are known for poor shift quality, and blowing up rather spectacularly... apparently they copied a lot of the Sachs Duomatic design, but they didn’t do the best job of it.

However, one of the big problems with the old-school brakes was... if it was Sturmey-Archer, they ran the brakes through the gearing. Braking in first gear was marginal on a SA 3-speed coaster brake hub. Braking in 3rd gear was... not pretty.

I find that the Duomatic’s brake is actually pretty good - easy to modulate, enough power - though. Then again, I’ve heard claims that the Sachs coaster brakes were some of the best of the vintage ones.

S65 > bhtooefr 01/27/2017 at 14:12

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Well I am building a fixie...

TheRealBicycleBuck > bhtooefr 01/27/2017 at 14:20

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One day I will fall into the recumbent trap and I’ll have to worry about more complicated gear ratios. Until then, I’ll stick with the 2x9 & 3x8 setups derailleurs on my diamond frames. My only unusual setup is moustache bars and barcons.

Cé hé sin > bhtooefr 01/27/2017 at 14:22

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Pah, that’s simple.

I’m convinced that this wasn’t designed by humans.

Interestingly, I’ve driven a (actually three) Citroen C3s with the Sensodrive automated manual.

It was designed by Sachs, now part of ZF.

bhtooefr > Cé hé sin 01/27/2017 at 14:24

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I didn’t say it was complex , just that it was unusual. ;)

Also, IIRC, the Sachs Elan is actually far worse, even though it only has 12 ratios.

The Lurktastic Opponaught > bhtooefr 01/27/2017 at 15:46

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+1 for mentioning Sheldon on oppo.

The Lurktastic Opponaught > TheRealBicycleBuck 01/27/2017 at 15:49

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I’m thinking about a catrike with a rohloff once my back finally gives out and I have to retire the diamond frames. I’m afraid the fat bike I’m about to buy will be my last upright.

TheRealBicycleBuck > The Lurktastic Opponaught 01/27/2017 at 16:05

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I’m not a fan of the steering on a Catrike. With the handles mounted directly on the king pin, the movement feels strange to me. I prefer a design with a separate handlebar with cross links. It’s a bit heavier, but it feels better when cornering.