Patrick, I hope I am understanding what you are looking for, but the DOS freewheels are still made in the two tooth differential versions; it's only the three tooth differential version (16/19) that was discontinued.
I'm not sure if you are looking for DOS freewheels in this situation though as these are thread on and not splined If you are looking at a different wheelset on this hypothetical bike and a standard single speed threaded hub then the DOS will work: https://www.whiteind.com/product/double-freewheels Regarding disc brakes, to Eric's point I know of no way to have the quick change of gearing you are looking for with non constant chain length and a rear disc. Most single speed disc options that carry the disc with the wheel use sliding or swinging dropouts but these are not really something you want to be adjusting on the fly. A double chainring setup really is the simplest. It's a quick change and adds a few seconds to the process. If you adopt a constant chain length dual ring/cog setup, sliding dropouts (or an EBB) make the change even quicker as you just drop the wheel, swap the cog/ring and reinsert. -Dave On Sunday, October 15, 2023 at 10:19:14 PM UTC-4 Patrick Moore wrote: > Thanks, but I don't want that complication. I want (if I can get it) the > simplicity of my Riv customer gofast: QR rear hub, Dingle cog, long > horizontal dropouts. I don't necessarily need these means but I do want the > same end. > > On Sun, Oct 15, 2023 at 4:31 PM Eric Daume <eric...@gmail.com> wrote: > >> The simplest solution is to also use two chainrings, matching the cog >> difference (for instance, with a 16/18 Dos freewheel, use 42 and 44t >> chainrings). Then the 44/16 and 42/18 have the same chain length, and the >> rotor to pad relationship doesn't change. >> >> Or just use a disc front and a rim brake rear, and a forward facing >> horizontal dropout (like typical UJBs have) >> >> Eric >> >> On Sun, Oct 15, 2023 at 6:12 PM Patrick Moore <bert...@gmail.com> wrote: >> >>> Thinking out loud; help me clarify my thoughts. >>> >>> I think of devising a Monocog replacement, with 622X76/29X3" wheels, but >>> instead of a mono cog, with a duo cog. This hypothetical bike would have >>> disc brakes. I don't want to use a chain tensioner, and I prefer to take >>> advantage of the greater gear ratio differences between cogs of different >>> sizes compared to rings with the same tooth differences, and of the >>> consequent smaller axle movement required to adjust chain slack, so the >>> multiple cogs would be in the back and not on the crank. >>> >>> On my beloved 1999 Joe Starck Riv Road Custom fixie I use a 17/19 Dingle >>> on a Phil hub with a QR axle; it's very easy to stop, flip the QR lever, >>> move the chain, align the wheel, and tighten the QR. >>> >>> That's what I imagine for the Monocog replacement. >>> >>> 1. Disc brakes. But this bike would have disc brakes. I'd probably not >>> need more than a 2-t cog difference, but will your typical caliper/rotor >>> setup accept the 1/4" axle movement? (1/8" of axle movement is required -- >>> so they say; I've never measured it and take it on faith -- to accomodate a >>> 1 tooth sprocket difference.) >>> >>> 2. Two cogs. How to get 2 cogs onto a suitable "ss" hub with a >>> freewheel. The DIngle isn't made anymore and in any event wasn't made -- am >>> I right? -- with 2-teeth gaps. The Monocog has a freehub designed to take 1 >>> single Shimano-spline-type cog; there's no room for a second cog. >>>What >>> options does one have to get 2 cogs with a 2-tooth difference onto a hub >>> suitable for a QR axle? >>> >>> I realize that I could just use an old 7 speed Shimano freehub, and I >>> might end up doing that, but I'd prefer to have a hub that does not require >>> a wide stack of spacers. >>> >>> 3. Axle type and dropouts/trackends/thru-axle holes. I know that long >>> forward-facing horizontal dropouts, a QR axle, and a hub with 2 cogs on 1 >>> side allows very easy manual shifting, as this sort of shifting goes. I am >>> also pretty sure that a good builder can use 135 mm OL spacing and still >>> give me the stay clearance I need for true 3" tires, so I'm inclined to >>> stick with this very old-fashioned wheel attachment method. >>> >>> But if there are other wheel attachment methods that allow you to easily >>> move the chain from one cog to another, I'd be interested to learn about >>> them. Sliding dropouts? >>> >>> Are there any other things to consider ? >>> >>> Thanks, Patrick Moore, who had a nice ride to church and back today on a >>> pretty Fall day riding the Monocog with 72 mm tires and a single 65" gear >>> despite the bosque trail sand and the rear tire knobs occasionally >>> "whisping" on the chainstays (I fixed seatstay clearance with a hammer). >>> The Silca Impero with Campy head and the Road-style BB7s pulled by non-aero >>> DC levers are ironic but in fact work very well. When braking from the >>> hoods you simply pull from a bit lower down on the lever; and the Impero's >>> fat barrel moves lots of air fast into low pressure tires; 13 psi this >>> morning and it could have been lower. >>> -- >>> >>> ----------------------------------------------------------------------------- >>> Patrick Moore >>> Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum >>> >>> ----------------------------------------------------------------------------------------------------- >>> >>> Executive resumes, LinkedIn profiles, bios, letters, and other writing >>> services. >>> >>> >>> ----------------------------------------------------------------------------------------------------- >>> >>> *When thou didst not, savage,* >>> >>> *Know thine own meaning, but wouldst gabble like* >>> >>> *A thing most brutish, I endowed thy purposes* >>> >>> *With words that made them known.* >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "RBW Owners Bunch" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to rbw-owners-bun...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/rbw-owners-bunch/CALuTfgvSea80hxHZ7mMEUxzpaR551T6Q5%3DNLpAvr%2B0QOQ3rh6g%40mail.gmail.com >>> >>> <https://groups.google.com/d/msgid/rbw-owners-bunch/CALuTfgvSea80hxHZ7mMEUxzpaR551T6Q5%3DNLpAvr%2B0QOQ3rh6g%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "RBW Owners Bunch" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to rbw-owners-bun...@googlegroups.com. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/rbw-owners-bunch/CAHFNW5BLmG4%3D1ydCiu5yZ2-Z-2127DHs6%3DuozLQd-a0d7gzY1w%40mail.gmail.com >> >> <https://groups.google.com/d/msgid/rbw-owners-bunch/CAHFNW5BLmG4%3D1ydCiu5yZ2-Z-2127DHs6%3DuozLQd-a0d7gzY1w%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > > > -- > > ----------------------------------------------------------------------------- > Patrick Moore > Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum > > ----------------------------------------------------------------------------------------------------- > > Executive resumes, LinkedIn profiles, bios, letters, and other writing > services. > > > ----------------------------------------------------------------------------------------------------- > > *When thou didst not, savage,* > > *Know thine own meaning, but wouldst gabble like* > > *A thing most brutish, I endowed thy purposes* > > *With words that made them known.* > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. 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