In the days before neo magnets, it was often necessary to use gearing on machines of 8ft and above to get a reasonable cost and weight of alternator. The best machines even then were those such as Jacobs, who neither spared the cost or weight to use direct drive.
With wound field machines there was no point in trying to extract power in less than 10 mph winds as it was wasted in the machine field. The penalty for low ratio gearing was small as long as you used high quality hardened gears ( belts were far from good). The gearbox even then was often the weakest link in the chain with regard to life, reliability and noise. This even remained true in larger commercial turbines and even the big ones are now going to direct drive. Trying for more than 3:1 speed increase for small machines was a step backwards and I see you mentioning 20:1 ( I pass no comment).
With the introduction of a decent magnet material at reasonable cost the justification of gearing for our size machines vanished and it has become possible to extend the low wind limit downwards to about 6mph at sensible cost and without iron in the alternator and a higher cost of magnets the possibility of even lower wind speeds seems possible, but wind is never cost effective in poor wind areas just as solar doesn't become cost effective in low sun areas.
Flux
