tcs

Yes, models from Sturmey-Archer and another from Eagle (a Bendix reproduction).

CS-RF3 for caliper brake; CS-RK3 for disc.

djb

re 2 speed igh, a few years back I knew someone who bought an Ikea branded winter city bike, all aluminum frame, disk brakes and a 2 speed igh with belt drive.

upon remembering this, it was an automatic shift 2 speed igh

tcs

The now discontinued Ikea Sladda bike was fitted with the now discontinued SRAM Automatix two speed. SRAM ceased production of their entire line of IGHs in early 2017.

Sturmey-Archer currently offers a manual ('kick-back') shift two-speed, the S2, and an automatic shift, the A2. Both offer a 1:1 low gear and a 1:1.38 high gear.

In 1970 cycletourist Colin Martin rode from England to Australia on an Alex Moulton bike fitted with a Sachs (the company was later purchased by SRAM) two speed hub and two chainwheels and two cogs. The bike therefore had a 'flat land' two speed range and a 'mountain' two speed range. The chain was moved by hand in response to conditions encountered.

Happy Feet

The goal would be a loaded touring bike based on a converted rigid mtb I already have. Steel frame, easy to cold set. As it is I have what I want in terms of bikes for regular road touring and off road touring so there isn't much practical need for building yet another platform in those areas. However, I have a good frame and lots of parts to build a conventional four pannier bike so without practical considerations I can experiment a bit. Boredom with derailers makes me look to something different but not so far as the expense of a Rohloff because I doubt I would ever use such a bike to its fullest extent.

I've have several SA hub'd bikes and like the simplicity of design so I could just go with that but I think the restricted range would be a bit of a pita for loaded touring on steep sustained hills. Most everything I do seems to involve a mountain pass of some sort. A hybrid double/triple IGH would be fun to build and withinin my experimental price range.

https://www.sturmey-archer.com/en/pr.../detail/rx-rd5

BobG

Wrap your heads around this drive train!



courtesy of Charles Siple, Greg Siple & Bicycling Magazine April 1, 1965

djb

this is becoming a "compilation of wacky and wonderful bicycle drivetrains" thread.

thanks bob, I personally think it would be required of riders to loudly bbbbwwlftttt bbbwwfftttt with their lips as they brake, to make that truck engine braking sound, or it just wouldn't be realistic.

Happy Feet

From the looks of it they were designing an air brake system for bikes. I wonder if they could have imagined current hydraulic brakes and electronic shifting.

BobG

Is this in reply to the "Checkered Flag Special"? If so that is just pure tongue in cheek, the April 1 issue of the magazine!

I guess the idea was to pedal downhill like heck to build up air pressure in the sealed tubes. On the next uphill you flip the valve lever and the compressed air is released to push the piston and turn the cranks for a boost up the next hill. If it also works as a brake that must mean it has fixed cogs on the rear.

Just a prototype, maybe they hadn't figured out the braking part yet!

djb

What would be cool would be to make a good seal between that cylinder thing, figure out how to mix fuel and air, I dunno, atomize it? And then light a match to make a teensy explosion that could push this cylinder thing down real fast like.
could work
some sort of "motor " , but on a "cycle"
I think this merits some tinkering

Tourist in MSN

That five speed Sturmey Archer hub could work. Using a five speed cassette to approximate the five speed IGH in the calculator. Something like this:
https://gear-calculator.com/?GR=DERS...N=MPH&DV=teeth

For the crank I used an older road triple (52/42/30) which Campy used for their square taper cranks. FSA still makes a road triple, but not sure what the chainrings are.

And chose 20T sprocket. Calculated a five speed cassette that would be equivalent to the IGH, but the 13 and 31T sprockets are slightly off since a sprocket has to have a whole number of teeth for the calculator to work. Used 26 inch wheel.

There are a few redundant gears there, but you could play around with different chain ring sizes to get rid of some of the redundancies.

I did not read any of the PDFs, so I do not know if they have a minimum chainring to sprocket ratio. Rohloff sets a minimum chainring to sprocket ratio of 1.9 for riders that weigh less than 100kg (plus a few other restrictions), the reason for that is to prevent too much stress on the internal parts in the hub. My point is that in first gear on the hub, with a small granny gear on the crank you would put a lot of stress on some of the internal parts. It would be a major bummer to start cranking up a steep hill and suddenly shear off one of the planetary gear shafts or start stripping off some of the spur gears.

Yeah, that five speed IGH with a triple could work. Would have 15 gears and cross chaining would be insignificant..

For discussion purposes, this is the gearing on my folding bike, I am using an approximation of a triple crank in the calculator to substitute for the 3 speed IGH. Bike has 24 inch wheels, 8 speed Sram 11/32 cassette on a Sram Dual Drive rear hub, 39T chainring. The 29 and 53 sprockets are approximations of the actual gearing, Has 24 gears. With short chainstays, there is some cross chaining but not as bad as would be with a real triple.
https://gear-calculator.com/?GR=DERS...N=MPH&DV=teeth

Happy Feet

Thanks for that reply TiM, I have to think about what you wrote for a bit.

Off the top though, if we use the 1.9 ratio as a limit, what would the best combination be to allow the climbing of steep hills fully loaded while still not over stressing the hub? What would one choose for the Rohloff? I am admittedly, not a gearing expert.

Tourist in MSN

I think Sturmey Archer instructions should be used, if any.

My Dual Drive, if I recall the only constraint from Sram was that it should not be used on cargo bikes, but your Sturmey Archer link said the Sturmey Archer was designed for heavy duty use.

The Rohloff has a third planetary gear that acts as a low range, so the Rohloff can put a lot of torque onto the non-drive side of the frame. Sturmey Archer can't put that much stress on the frame because the gear range is much smaller. If you took that Sturmey Archer five speed and added a low range to it so that it was a 10 speed, and the lowest 5 speeds were in the low range and your existing 5 speeds would be the high range, that is basically what Rohloff did. The Rohloff is 14 speeds, gear 11 is direct drive.

I would think that a 30T chainring and 20T sprocket like I used in the calculator would work ok, but I still think it would be a good idea to verify with Sturmey Archer that it would not over stress the hub.