use external frame rucksack as 'bent bike seat back

D: pic of a vintage 80s Kelty rucksack.
Various other external tube frame ones are available.

I propose using the rucksack as a modular seat back.
Just have 2 posts the bottom of the tubes mount on.
The tube base would need to be modified slightly.

When you get up from your bike, the seat back goes with it.
This means anybody who steals your bike could not in fact ride it away.

This kills 2 birds with one stone.
Why have a seat back AND a rucksack for road trips?
I will not be able to afford to build the Mark I this year.
I might submit the design to this year's everybody-bike contest.
But this is one way to keep the weight down.
I am still intrigued by the challenge of matching the weight of a Flevobike GreenMachine.

Finding a toothed industrial belt of the correct length to replace a chain is proving difficult.
A one-size-fits-all 'bent bike solution would involve a chain arrangement involving a variable triangular layout.
That way, the single belt would always be the correct length.
See an earlier blog on that.

The Mark I, sans under-seat-suspension that looks like a pair of thudbusters, should be relatively light.
However, I have no interest in riding a bike without suspension.
I'd be tempted to have a 26" up front- 24" minimum.
And a 28-29" at the rear.
This would reduce impact when all that weight from camping gear is on the rear tire.
A seat and pedal boom that can extend forward would keep the weight distribution 40% forward/ 60% rear.