Joerg wrote:

It must be supported by muscles.
Otherwise you run a real risk of neck pain.
That is something I've heard road bike riders
complain about.

Great, this has been my intuition as well!

How could pedaling "empty" decrease the
speed? The ticking freehub causes a very
small amount of braking force. If you pedal,
the ticking will drop in rate, so less drag.
However, the difference is probably so
miniscule that it really doesn't matter.

OK, let's rephrase:

If one pedals normally, the bike goes forward
because the energy from your body and legs is
transferred to carry the bike forward.

But if you pedal "empty", i.e. too low gear for
the current speed, where do the energy go? a)
same as above, only you won't notice because
the effect is so small; or, b) somewhere else?

And if b), what aspect of the construction (or
physics perhaps) is the explanation for this?

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