Yeah, I had one of those 'dynamos' on my Schwinn for a while.
Driven by the tire tread through a small knurled wheel, with crappy bronze bearings, maybe 20x faster than the wheel.
Driving ~10W of incandescent bulbs fast enough to see by, got old real fast.
Nowadays, LED bulbs and primary batteries make more sense for bicycling.
For power generation, human powered dynamos don't really make sense either.
Mike Halloran
Pembroke Pines, FL, USA