Madscientist, I had exactly the same questions about the fluid dampers and Lieb's ideas.

Poly, that's a very interesting look at harmonics. I agree that bobweight will change the amplitude of the vibrations but not their frequency, which I believe is due to the physical dimensions and material of the crank.

Here's a question for you - Given that gray cast iron has a modulus of elasticity of 20EE6, while nodular cast iron and steel are right around 30EE6, does the material have an effect on the resonant frequency or just the amplitude?

R.