Dynamo hubs

because someone puts it on an un-machined rim, it doesn't mean it will always function well in that scenario. It is fairly obvious that when the rim gets wet the small band on the dyno isn't going to be able to provide the grip to hold contact through the water without it requiring far more force to hold the dyno against the rim.

1. Neither rim brakes nor the dynamo demand a "machined rim" but a rim with, more or less, a braking surface, viz. more or less parallel rim walls. The surface on machined rims wears down anyway rather quickly. Classical bad weather rims such as the Ambrosio Nemesis don't have machined sidewalls. There is nothing about the design of the dynamo that I see could require machining--- if so it would quickly start to fail as the rim surface starts to wear down.
   
2. The rim wall does not even need to be very deep--- less demands that most "modern" shoes.
   
3. Water? A machined surface is not more immune to water films.
   
4. Apparently a large number of people are using the dynamo for long distance touring. According to the maker "It works slip-free and with unobtrusive reliability even in the wet". I see no reason not to believe that claim.
   
5. I can see some problems in extreme cold, snow, mud etc. but that is where the accumulator based solutions come to bloom: lights are powered by a battery that is charged by the dynamo.