For claims like these, I think it is important to get somewhat specific about what claims are actually made. The claims are argued with logic, and as such, the claimant will eventually run into contradictions - which are the same observations that led to development of real physics. I would argue that in most cases throughout human history, the claimant then alters the story to either:
- temporarily avoid the contradiction, or "argue around it"
- allude to credible science that actually describes something else
My favorite example of #2 is Thorium laser powered cars. If you start reading, you will find articles written by people with no relevant knowledge. However, if you follow the rabbit hole on the internet long enough you'll rind references to actual science that proposes accelerator driven subcritical Thorium reactors, where the "laser" is really charged particle beams, but the innovations that allows it to be done with lasers, without producing fission products (completely absurd), and small enough to put in a car - that's secret. This point is also suspiciously close to where you'll find the donate button. That was a bit of a tangent.
After watching the videos, I'm convinced this is a case of #1. I will argue this by using these two diagrams from his video.
This is the same thing shown in the question. I wanted to be sure that the interpretation of the claim was correct. It is. Here is the 2nd part of the argument.
I would argue this as somewhat of a "smoking gun". Let's say $\theta$ is the angle from the vertical where the foot lies. He is actually arguing that when $\theta=0$ the torque is non-zero when using the z-crank, although it is zero when using a normal crank.
If one's college level first-year physics class did its job, they should be able to disprove the claim with this information, as it is plenty sufficient. The above thinking represents a fundamental misunderstanding of the physics at work. We need not look at the rest of the claims, or his approach that you can use a:
greater portion of rotation for power generation
His point form the above two images is sufficient to refute the claims. The core misunderstanding is believing that the "torque" comes from the direction of the crank material locally to the shaft. No, torque is based on where the force is applied from. The foot applies the force. The pivot is still in the same place. The pivot is in the same place, the force is in the same place (establishing $\mathbf{r}_1=\mathbf{r}_2$), is the same magnitude, and is in the same direction (establishing $\mathbf{F}_1=\mathbf{F}_2$) - the torque of the two cases is the same ($\boldsymbol \tau = \mathbf{r}\times \mathbf{F}$). He says it's not. I'm finished, because the entire point of the Kickstarter project is built on the idea that they're not.
