the only reason youd need to straighten your legs at the top of a pedal motion would be because your starting off and need to start with your weight on the other side of the bike that your naturally on. orrrr... your using poor pedalling technique whilst not clipped in.

When a leg is straight, all weight is on that leg.

to start it on its up journey you dont need to "lift it" just sway your center of gravity over to the bent leg and the pedal will drop down as the pedal becomes more heavily loaded (more force is applied), lifting up the bent leg. Easy.

The way serious describes cycling whilst out of the saddle, hed have us all stumbling instead of pedalling in nice controlled circles.

Without wishing to appear arrogant, I know my fair share of dynamics.  Id like to think I know a little about conservation of energy too, having spent the last two years of my life solving problems just like this.  The internets a tricky medium to convey this over as most of mechanics relies heavily on diagramatic methods.  But Ill do my best and write one more paragraph on this.

Work done = force x distance moved in direction of said force.

In this case youre talking about the benefit of using weight.  So, youre talking about using your potential energy (as an object high up) as a power source.  However, since at the end of a ride your body is in the same position it started out at, the total potential energy is the same as it started at.  Consequently, any energy "given out" by using your weight on the pedals must be exactly equal to the energy used up to get it back to its initial state.  And thusly we have proved that the weight doesnt directly contribute to the energy put into the pedals, only to how well you stay rooted and consequently how hard you can push them round.  And obviously a recumbent is better at this.  QED etc etc, Im f***ing off to bed.

In order to release energy a body has to drop though, yours remains at the same point, all the energy used comes from your leg muscles. moving your weight just balances it over the bike. Unless you pull down on the handlebars you cant increase the force over the actual weight of your body which is what I was getting at, with a recumbant you can use all the muscle strength available.

I have seen one that you can use your arms to pedal with as well as your legs.

Quote from: funkychicken9000Without wishing to appear arrogant, I know my fair share of dynamics.  Id like to think I know a little about conservation of energy too, having spent the last two years of my life solving problems just like this.  The internets a tricky medium to convey this over as most of mechanics relies heavily on diagramatic methods.  But Ill do my best and write one more paragraph on this.

Work done = force x distance moved in direction of said force.

In this case youre talking about the benefit of using weight.  So, youre talking about using your potential energy (as an object high up) as a power source.  However, since at the end of a ride your body is in the same position it started out at, the total potential energy is the same as it started at.  Consequently, any energy "given out" by using your weight on the pedals must be exactly equal to the energy used up to get it back to its initial state.  And thusly we have proved that the weight doesnt directly contribute to the energy put into the pedals, only to how well you stay rooted and consequently how hard you can push them round.  And obviously a recumbent is better at this.  QED etc etc, Im f***ing off to bed.

It clicks lol. Fair nuff mate I gets ya.

chucksbikes.com has a cheapie bent for $499.