The bicycle components being used are standard bottom bracket (BB) shells
that are mounted to the Minitec extrusion which allow them to be moved fore
and aft. A square taped bottom bracket was threaded into the BB shell. A
standard crank-set is attached to the BB which allowed for various gear ratios
to be used during testing. The crank-set incorporated a 53 tooth chain ring
which was connected with a chain to a second sprocket mounted on a second
bottom bracket. This small sprocket is directly coupled to a larger sprocket
which was connected through a chain to an 11 tooth sprocket mounted to the
rear gearbox. The gear ratios may be varied by changing the sprocket sizes on
the second bottom bracket. Using this design, gear ratios between 4.81:1 and
14:1 can be produced which yields between 481 rpm and 2300rpm at the
Chains
Crankset
Pedals
Second Chain Ring
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propeller, with a predicted rider input of 100-150rpm. The appropriate ratios for
maximum performance were finalized during testing.