Originally Posted by
Tourist in MSN
Have you tried to turn a dynohub by hand when it was not attached to a rim? It takes a lot of energy to start to turn it. I doubt your tire will have sufficient grip. And even if it did, you might not be able to go very fast on the bike.
I haven't had the chance of holding a dynohub in my hands, let alone check its inner drag.
Your suggestion seems quite reasonable to me,
Tourist in MSN. After all, light output always comes at an energy cost.
It didn’t occur to me that the dynohub spinning drag must be much higher than that of a side bottle dyno and that it is only overcome due to the rim diameter leverage. According to that, I also gather that in my configuration the dynohub should be much heavier than they are or that some kind of compression spring would be needed (quite a claptrap to my mind) to force it down to hold grip against the tire tread. That weight, plus the added drag of an oversped dynohub is what would work against acceleration and speed.
Anyway, thank you very much for your enlightening reflection (unintended pun). A trashed bad idea saves time and money.
Cheers to your health.