A traditional bicycle 'dynamo' (actually an alternator) achieves well-regulated power for a simple load with a clever combination of internal resistance, reactance and magnetic saturation. For an incandescent bulb of known power this is a mature and efficient implementation.
However, modern loads are more complex. They may include flashing LEDs, battery charging and transient loads. A single solution to suit these varying loads is far more wasteful because it cannot match the source impedance with the load impedance for optimal power transfer.
A variable transformer operated by a power matching algorithm would provide a more flexible match, but such complex transformers are no longer necessary when digital switching and inverter technology can simulate them more compactly.
This suggestion is to provide maximum-power matching for a range of loads in the form of a 'smart rectifier', with some user or automatic control to obtain 'free' power downhill while minimising extra effort when there is a heavy kinetic load uphill. It could be implemented using a 3-phase hub motor functioning as a generator, providing additional possibilities of regenerative braking and motor assist. Other generator applications will also benefit.
The objectives can be met with a single TAPAS board.