Not seen this gear set up before .

[bagpuss]

As seen on flickr . This lovely Viking Hosteller, with S/A FW rear hub + twin sprockets and a double chainset at the front
I have seen similar with a 3 speed hub and twinn sprockets and a single chainset ,but a double as well.....

1959/60 Viking Hosteller by Brian Jones, on Flickr

 

[keithglos]

One good shove on the pedals in the lowest gear should explode the Sturmey archer.

Keith

 

[brj]

Re:

Thanks for the nice comments, the frame has not long come off fleabay, the owner bought it new but never built it up.He has just retired to the Isle of White and didn't want to take it with, got caught up in the floods trying to get it too, then the lockdown focused the build up !
Re input ratio and torque reaction, I live in the Cambrian mountains, most of my riding is up steep stuff and it's been fine, I have kept the input ratio in lowest gear to approx 1.6:1 (which gives 27") but I will happily post pictures of any failures (if i can work out the blimin BB codes !)
cheers, brian.

 

[keithglos]

If you bear in mind I ceased repairing shattered SA gears in the mid 50s, from memory low gear is -33%, has 2 trains of epicyclics, and estimating the chainring at 38 and rear cog 26 that would be around 27 inch gear as we quoted gear ratios then.
I think the problems started with teeth breaking off the sun wheel.

By 1949 I consistently had all my cycle gears in direct drive.

Keith

 

[brj]

Wheel (700c) and tyre (28mm) = diameter 27" x 34/22 = 41.7", 33% of of 41.7" = 13.7", 41.7"-13.7" = 28"
I'll keep and eye on the sun gear, thank you.
i'm a little confused by your term "direct drive" ? do you mean 3rd gear on a 4 speed SA or do you mean you'd got rid of all your SA equiped bikes ?

cheers, brian.