cosmos bike

[zapata]

on the inventors tv show last week was a new type of bike gear mechanism which is claimed to be more efficient than normal bikes.
it's based on a planetary gear and looks a bit odd but seems to work.
you can see a short video of the bike in action.

http://www.abc.net.au/tv/newinventors/inventions/

the inventory reckons he's planning to sell kits that can be retrofitted to existing bikes.

[stryker84]

has been discussed before in this thread here.

http://www.bicycles.net.au/forums/viewtopic.php?t=1963

i don't know a thing about it, and haven't clicked through to it, but seems the general consensus is "tell him he's dreaming!"

must look this up a bit more...

[Bnej]

Conventionally, when using planetary gears, you select the inputs and outputs on the sun, planet carrier, or orbital of the gear set - this is how the schlumpf bottom brackets work.

For some reason this dude's decided to attach cranks to an actual planet gear, which causes the two different pedal strokes.

All meshing gear systems are less efficient mechanically than a direct chain drive. You lose energy in friction as the gears mesh. The only possible improvement he could have is by using different muscles on each pedal stroke, but IMO it's just whacky. When he started talking about using it on combustion engines... arrrgh *head explode*

[zapata]

yes it seemed a bit far fetched and also your legs are stretching out at different lengths as the crank assembly orbits the sun gear.
your leg is supposed to stretch out maximum length for best efficiency.

it took him 40 years to develop but he reckons he goes faster with same energy input.

[McPete]

With the same cadence, yes. It's a higher gear, I would imagine. It'd be a bugger to stand and pedal if you came to a hill though.