Oh my God, I'm so amazing!

there was a double freewheel bike with one reversed next to the normal freewheel and an idler that let the chain go round both, stop pedaling then pedal backwards to climb hills in an easier ratio.

I've seen a diagram of this setup and no matter how hard I studied it I still couldn't get my head around it! Supposedly it worked but the pedalling backwards bit was just too awkward, or something.

I think eggpie here on the forum has the book with the diagram...