I wanted create a for a long time bike with gear box in the bottom bracket
as I Expanded a rim rear hub and built a custom coaster,
I could not have gear .... and I missed it!
I'm inspired by old bikes (1900), and tractor mower gearbox!
I used bike gears, plexiglass and machined parts
I put two weeks to get the idea and create plans
and about 2 months to realize the gearbox!
there are three speeds and axis drive and output are the same
the selection system is brass
plexiglass box is to see the mechanism
First I made plans and gear ratio
Plans were made to the scale to facilitate manufacturing and various tests of setting up