Very silly question - or is it?

[Norm]

I don't necessarily think that speed = efficiency. As I said above, I can travel further and for longer as well as faster when comparing cycling to waddling running.

And the OP's questions was about cycling and running (specifically, "Why is it more efficient cycling that running?") rather than, say, getting the milk out of the fridge. The most efficient way to get milk from the fridge in my house involves the use of slave labour children.

 

[vernon]

Back on topic then.
Anyone know scientifically why cycling is more efficient than running?

I've already done that. Read the post about raising the C of G of the body when running vs contant height of C of G when cycling.

 

[vernon]

have to factor in momentum I'd have thunk - stop running and you are do just that, stop, stop pedalling and you roll on. (or backwards if on a hill )

Momentum has got nothing to do with it. Trust me. I was a Physics teacher.

 

[killiekosmos]

Has it not got to do with number of factors:
low friction associated with rolling wheels, mechanical advantage of gearing etc.

Easies explanation I can give is that runners/walkers still have to work to go downhill, cyclists don't!

 

[vernon]

Easies explanation I can give is that runners/walkers still have to work to go downhill, cyclists don't!

Tell that to someone going down a 1 in 5 on a fixed wheel bike.

 

[Gixxerman]

Tell that to someone going down a 1 in 5 on a fixed wheel bike.

LOL! My computer is now splattered with coffee.