> > battery operated bicycle lamps also, the
> > dynamo (is it called that in English?) has been
> > working just fine for 100+ years...
>
> Except that when the tyre sidewall is slippery or when stopped at traffic
> lights etc, it's nice when your lights still work!
>

Bicycle tyre sidewall dynamos are mechanical abominations with horrendously
low efficiencies. Probably under 10%.

"Hub dynos" or similar modern alternatives that wave rotating magnets past
fixed coils, have every high energy conversion efficiencies. My own
experiments with a hub-dyno MANY years ago showed that the rider could not
tell whether the light was on or off. Load was probably 2 x 3W or maybe 6W +
3W.

Doesn't have to be a bulb light.Using LED's actually doesn't improve
efficiency over a bulb if an electronic converter was used to optimise bulb
voltage BUT for a varying voltage a LED lamp may be a good idea.


        RM


> Even with a small secondary cell to cover brief interruptions from the
> dynamo, I prefer to keep my cycling as effortless as possible.  So I
> recharge my lights from the mains supply at home (or from a solar cell
etc)
> intead of powering them as I ride.
>
> A good bicycle headlight is at least 10W (ignoring the little candle-like
> ones!), that might be an extra 50-100W of dynamo effort, which is quite a
> lot for me!

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