How to Build a Practical Household Bike Generator (lowtechmagazine.com)

No, this will never be practical. By their own numbers, 100 watts at max exertion, 75 watts over 30-45 minutes.

0.0375-0.0625 KWH

Enough to run an 1800 watt electric kettle for, oh, 1-2 minutes?

Might or might not get a cup of coffee made