A Schlumpf mountain drive is 0.4 and 1.0.

I've always wondered if combining it with an 11 speed 12-28 would be practical. No overlapping gears, 583%, no efficiency loss at 1.0, and very close gear spacing with 22 unique steps, between 6.3-12% steps.

seems like you’ve done the work for us! A modern 1x11 provides the needed gears and is cheaper, lighter and easier to service than a dual drive or even a high end IGH - thanks! Until the gearbox, pinion driven folders come out, yours may well be the ideal setup then.

I built an CS-RK3 into a 622 rim with 42mm tires on to. I installed a 11 speed 11-42 cassette because mountain 11 fits on a road 10 speed free hub. I installed a 42 tooth chainring so as to maintain a 1:1 drive ratio. The derailleur was a Shimano mountain M8000/9000 shifted with Road 11 speed shifters and aTanPan to translate road/mountain pull ratios.

The package resulted in a range of 21-146 gear inches & 680% range. I mostly cruised in 3rd/overdrive in the 24-32 tooth cogs at 16-22mph. The hub worked perfectly fine.

I've since moved that wheel set to Mrs. Base2's Salsa Marrakesh and installed 622x32 tires. 20.5-138 gear inches. She doesn't ride terribly fast, but the tall gearing allows her, her preferred 60-70 cadence with out being in the fast wearing 11, 12, 13 end of the cassette.

Hypothetically, on a 20 inch 406, with 50mm tire you'd have 15-102 gear inches with out exceeding 1:1 which is that hubs actual limit any way. A derailleur that is long enough to accommodate a 42 tooth big cog has it's own concerns with ground clearance. 1:1 gets you your 15gi low no matter what chainring & big cog you choose as long as they are equal tooth counts. All you need to do then is decide how big of a chainring nets you the top speed you want and choose ring and cassette range accordingly.

I like the RK3 and am seriously considering building another wheel set so I have another of my very own.

My only complaint, if you can call it that is the freehub engagement is a function of the ratio selected. (Underdrive/direct/overdrive) This is magnified by the cog selected. Meaning if you are coasting in overdrive in a big cog you may need to turn the crank set as much as a ⅓ to ½ revolution to engage the pawls to drive the wheel. This is not really an issue in direct or under drive or towards the small end of the cassette. It's hardly a problem. Just a source of minor irritation, sometimes.

FWIW: I'm used to fast engaging free hubs and I tend towards faster than the utility/recreational cycling end of the spectrum. So, I may be hypersensitive to very wide range cassettes and hub engagement speed. IOW: YMMV.

I'm on board with you, that's the magic range. I try not to rain on someone's parade if they want to go a certain direction, and I commend you for doing same. The OP may read the above and have more questions for you. Like you've mentioned(?), 50T is still "experimental" status for you on 406. But 42T is definitely feasible, based on your past experiences. EDIT: Oh, I see the OP has already seen your comments!

Uh, no. SunRace purchased the IP & tooling for the Sturmey-Archer product line in 2000.

SRAM stopped manufacturing (& supporting) most of their IGH models in 2015 and all IGHs in February 2017. They inexplicably didn't sell the IP to anyone.

thanks for sharing your real word experience!
glad to know the SA hub can handle the 15 gear inch low as that was my main concern. It also does provide nice ground clearance while offering a very wide range so it may well be a great setup for small wheeled bikes.
Although as Ron points out this comes with a weight penalty and the entire range may not be used often.
Still I think I may try it in one of our bikes (have been tasked with building up 4 touring folders for the family!)

With the same cassette:
SRAM DD - 540%
Sturmey-Archer CS-RF3 - 516%



Back when this hub was introduced (2012 or there abouts) this question was asked on multiple forums. A Sturmey-Archer company guy named David Prosser said one could use a primary input drive ratio on the CS-RF3 of 22x34 (i.e. 0.65 to 1). Mr. Prosser said the hub had been tested to 780kgf-cm, the maximum tensile strength of the chain used in the tests.

Derailleur clearance with 16" wheels? Shucks, use the smallest rear derailleur made:

great info! Seems like the hub is pretty much bomb proof

Recent posters are concerning themselves only with the RD's upper jockey wheel clearance for big cogs, while ignoring the cage length necessary to wrap large ranges between big and small cogs. You cannot use a short cage (or even medium) to shift 11-50T! Luckily, most folders aren't ridden in conditions where a long cage is in serious danger. The cage is running close to the rear wheel itself and may well be inside the overlap of a large section (~40mm+) clincher. I wouldn't worry about it. That said, I really wonder how necessary a 15" to 18" gear really is on a folder. The low gears of modern folders are getting ridiculously high in order to provide satisfactory top end. A 39T to 42T chaining used to be common on folders but they are now in the 50T plus! Anything that can be done to bring this down is admirable. I'd be chuffed to have a 22" low on my folder. I've learned much in this thread that I intend to further investigate. Grazie.

You may wish to consider building the four bikes identically or quite similarly so the spare parts that you will carry on tour are interchangeable among them, thereby reducing the number, weight and bulk of the spare parts.

How would I play it? Four chromoly 20" (406) bi-folders with fattish tires; a 1x derailer transmission; wheels with no fewer than 28, 2x spokes; and Shimano hydraulics no lower than Deore with 180mm rotors front & back. All four bikes nearly identical save for individual fitment at the saddle, handlepost, grips and handlebar. KISS.

You need to update your knowledge to the state of the conversation in 2024. I have myself built and used a 11-46T cogset with a medium cage GS derailer (part Shimano Deore RD-M6000-GS, 10-speed) while having no less than 5cm of ground clearance on a 20"(406) wheel.



It works perfectly, shifting smoothly, crisply and quickly across the entire cogset, affording 21-86GI with a 47T chainring. It's actually quite amazing how well it works. I would not hesitate to recommend it.


​​​​​

Shimano Deore RD-M6000-GS

​​​Now, as for 50T max cog, there are videos on YouTube and on this forum channel which I have shared showing two other Shimano medium-cage RD that can span with a 11-51T cogset with varying success. Those parts are, in addition to the one listed above:

• Shimano SLX RD-M7000-GS, 11-speed
• Shimano XT RD-M8000-GS, 11-speed

​​
The point here is that you ought not be so categorically dismissive that it could work in the face of practical evidence that it can work.
​​​​​​

Shimano XT RD-M8000-GS rated for 46T max cog


11-46T cogset for the Shimano XT RD-M8000-GS part

Shimano SLX RD-M7000-GS, 11-speed






Finally there is a Microshift medium-cage RD, Reddleman will know which one, that can span at least 48T max cog.
.
.
Incidentally, a short-cage SS derailer like the Shimano Zee RD-M640-SS part can span a 11-42T cogset.


The trick in all instances, short- or medium-cage, is to finesse the chain length.

Oh, yeah, I think you're right. Sorry I got my IGH companies confused. That would explain why previous manufacturers using the Dual Drive dropped it completely. Anyway, thanks for the correction.

Microshift Advent’s medium RD officially spans 11-46T blocks for 9 speeds and is comfortably clear of the ground for highway and gentle gravel use. For more rocky terrain their Advent SS RD spans 11-38T blocks and was designed for 20” wheeled kids MTBs. Microshift Advent has a wide range of shifters and I’ve set it up on folding bikes with MTB, road and bar end shifters.

Their version 2 Advent X RD appears to have similar or slightly better clearance for a 10 speed 11-48T block and is compatible with their Sword shifters, but I haven’t tried this one to be sure about clearance.

At one point I had a folder with Advent and an 11-42T block and another folder with a used SRAM DD. I found that the DD added complexity and a degree of overlapping ratios in practice, and was an additional complexity to maintain or repair. I replaced that folder with another one with Advent and an 11-46T block.

It's like there's an echo in here. Or merely consensus. I think the killer app for the Dual Drive was Euro city bikes that people used to commute in business clothes, because it could offer a reasonably effective chainguard. That wasn't the case with Bike Friday, who made a lot of NWTs with DD, even though they already had an effective triple crank setup (prior to wide doubles); Might have been for the higher-high than a lower-low, or issues with a long-cage rear derailleur 25 years ago. But yeah, I avoid DDs due to the more complex maintenance and not having the facility to do so myself. I wouldn't turn down a Rohloff 14, the drain and fill lube sounds quite straightforward. For now, I'm infinitely happier with my 2X 405% versus my previous 1X 273%. Doesn't sound like a lot of difference, but it is.

Thanks for your other info, that may be useful if go lower than my 30T low cog.

I hate it when people play semantics games with me. That is a long cage derailleur by anyone's direct observation. If they are calling that medium cage in 2024, so be it. Everyone who wasn't just trying to score semantics points knew what I meant.

And I hate it when Rip Van Winkle types stuck in the past wake up to the 21st century, speak from ignorance, and play the tired semantics card when their outmoded opinions are found wanting for fact, relevance and precision.

Is this the rear derailleur that you're talking about? If so, I'm getting it for the mods to my Origami Bull (once I'm physically capable to ride again)...
https://www.amazon.com/gp/product/B0...718ZUBOU&psc=1

The Sword RD is different from the Advent X RD and comes in two lengths. I’m not sure what the medium version is like, sorry. I suspect it’ll be okay but it might be worth comparing with the Advent X RD if clearance is a dealbreaker. I can’t see the long version working with a 20” wheel, same as the Advent long cage RD designed for 2x setups.

In theory though, there’s nothing stopping you using Sword shifters and the Sword 10 speed 11-38T block with the Advent 9 speed super short RD, beyond inserting a barrel adjuster in the cable housing somewhere…

So, it can very likely be pushed to and work fine with this $38, 9-speed, 11-50T job:

I want to look into the recommended maintenance of the IGH portion first, but I’m really tempted to put one of these on my Big Dummy. I didn’t put a Front Derailleur on it when I built it and foolishly bought a medium cage Advent derailleur rather than the long one.

You know, this was the original plan, at least the 4 identical bike part. But we are on a steep learning curve regarding folders and especially folders that kids can travel with, ride, fold and carry themselves. My 9 year old daughter is a skinny lil thing. We must also take into account that us grownups will need to pack and carry more than our own share as the kids will do less.

Then there is the fact that very few folders are available for purchase - much less test ride - here in Mexico, and none at all in Chiapas.

So Im in the process of sourcing and building up at least 4 different folding bikes to test here with the family on short outings and overnight camping trips. If we end up with an extra bike or two I really don’t mind! 😃

We have arrived at similar conclusions as yourself regarding fame material, brakes and tire size. I think after this initial big tour we may even decide to all switch to one model of bike, or perhaps two, or keeping a small stable
to choose from depending on the trip.

Two of the bikes that are available for purchase online in Mexico are the Zizzio Forte and the Dahon Mariner 40th anniversary edition. Neither are steel and neither have disc brakes though. We also can’t test either before buying.

So far we’ve purchased an Origami Swift - which is great! Big tires, hydro disc brakes, cromoly frame and a fast - albeit larger - fold. But it does fit into a wheelchair bag and I’m sure would be fine on trains and such. Maybe even as checked baggage. Ride quality and luggage carrying capacity are excellent. The frame is too tall for the kids to ride it though.

We are also waiting on an FnHon Storm frame, based on you very own! It is for the Storm that we are considering the SA dual drive hub. This *should* be short enough for the kids to ride and hopefully manageable enough to fold and carry. But we will see.

We also ordered a 20” Takachia Tiime trifold from
Singapore. That should arrive in a couple weeks. It is cromoly steel but has caliper brakes and can only for 1.35” tires. So we will see how that goes.

Anyway we are looking forward to testing and reviewing all these bikes, and are also very open to suggestions!

First I'll ask if you do the maintenance on your existing freehub, disassembling, cleaning and relubing? The F30 hubs have pretty much the same service interval, and service is pretty much just more of the same kind of thing.

From the Instruction Sheet: "No routine lubrication is required. During a major service, the hub greases should be replenished or replaced especially for transmission parts of internal hub."

CS-RF3 disassembly:

CS-RF3 assembly:

With a 58cm top tube, the FnHon Storm is not a small bike. Caveat emptor.



Instead of bringing the bikes to Mexico and then back out to Asia, you may wish to consider instead flying to Bangkok, KL or Jakarta and spending a week there acquiring the bicycles immediately prior to the tour.

I don't know where in Asia you are planning to tour, but Aeroméxico does a CDMX-Tokyo direct haul. Once there, the Asia-Pacific region is your oyster. Garuda flies Jakarta-Tokyo direct.

yes this is definitely an option, although we’re still learning and testing as much as possible beforehand.

our itinerary will be Mex—Tokyo, ride Japan for a couple weeks, then Tokyo—Bangkok and ride Thailand for 3+ weeks. Any extra flights really put us beyond budget as there are 4 of us!

Would Tokyo be a good place to source folders? If we were to fly anyplace else, wouldn’t Singapore be the best option? It seems like it has become the Mecca of folders. Although that United Trifold only available in Indonesia is very intriguing — if only for the fact that I really think it could accept 18x2 tires! Which would mean ultra small (perhaps even gate check size) fold, disc brakes and fatties, although boo aluminum

On whether the United Trifold can accommodate a 50-355 wheel/tire from its stock 37-349 wheel/tire, note that the former is about 3.2cm larger in diameter than the latter.

How/where would I play it, climate permitting?

• Fly into Osaka's Kansai airport,
• Take the train from Kansai airport to Wakayama,
• Take the ferry from Wakayama to Tokushima on Shikoku island
• Tour Shikoku island and end up in Yawatahama
• While on Shikoku, take a side trip to do the Shimanami Kaido route
• Take the ferry from Yawatahama on Shikoku to Beppu on Kyushu island
• Tour Kyushu
• Take the ferry from Fukuoka or Kitakyushu on Kyushu to South Korea's Busan
• Ride from Busan to Seoul along the Five Rivers Bike Path

Or in reverse, flying in to Incheon airport in South Korea and cycling in to Seoul from the airport on a bike path. In either case, the Seoul - Osaka haul will be epic. If you've got the time and coin, that's the ride in Asia-Pacific, and if you're still keen when you roll in to Osaka at the end, simply fly to Taipei and ride Taiwan's East Coast. I'm getting a woody just thinking about it. 😂

​​​​​​The wife and I are big fans of Osaka. Friendlier, less intimidating, cheaper accomodation and fewer tourists than Tokyo (think Guadalajara vs. CDMX) while affording all amenities of a large city, with quick, easy access to Sakai, Kobe, Nara and Kyoto. I know two shops that specialize in folders if you are interested in sourcing your bikes there.

Don't be wedded to disc brakes. Rim brakes are fine and perfectly serviceable. All of my tours have been with rim brakes, in fact. But if you go with disc, make sure they are good, reliable brakes. Last thing you want is to be leaking or rubbing throughout the tour from the ghetto brakes that usually come stock on low cost bikes. It's a tour, not a ride in the park, where day in day out reliability is key. Biggest bummer on tour is to have to your bike worked on and not being able to ride. As you are a party of four, the chances that any one of four bikes will have a breakdown is higher than the chance of single bike. If the probability that bike A will break down is 0.01 and the probability that bike B will break down is 0.02, the probability that either bike will break down is 0.01 + 0.02 - (0.01 x 0.02) = 0.03. You get the point. Elementary probability is why I ride alone.