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@Greenbank
A simple dynamo (without any extra electronic magic) is a constant current device.
Simple bicycle dynamos will put out 0.5A and it is the voltage that is (roughly) proportional to speed. Therefore the power they draw is also proportional to speed but it is usually in the 3-6W range for normal human bicycle speeds.
Using a simple bicycle dynamo at motorbike speeds would just mean higher voltages (and therefore more power) and more likely to blow whatever is connected to it.
If the dynamo (or whatever is connected to it) has some internal electrical magic (regulator, over-voltage protection, etc) it there may still be a problem if that stuff isn't rated to cope with much higher voltages from motorbike type speeds. My old SON/Solidlights combo could cope with 45mph downhills on the bike, but may not have coped with 70mph.
If this is a different type of dynamo (it's not clear from the description) then who knows. My guess is that the lamp in question would quickly let out the magic smoke.