You can ditch the 3-speed hub, and keep it a 3 speed by fitting 3 x sprockets from a 10 speed cassette, in place of the standard 2 speed ones.
Narrower sprockets y'see.
The standard 2 speed shifter can be modified to have a third position to click to.
Or you can fit a friction shifter.
You also need a 10 speed chain.
I've had the kit for this conversion sitting on my workbench for months.
Just haven't got around to fitting it.
You can ditch the 3-speed hub, and keep it a 3 speed by fitting 3 x sprockets from a 10 speed cassette, in place of the standard 2 speed ones.
Narrower sprockets y'see.
The standard 2 speed shifter can be modified to have a third position to click to.
Or you can fit a friction shifter.
You also need a 10 speed chain.
I've had the kit for this conversion sitting on my workbench for months.
Just haven't got around to fitting it.