FWIW, swing pedals have been around for an age, they keep dying a death as the bearings don't last when you press on (nice lever pulling on a too short an axle stub) they also push the pedals outboard, so don't suit everyone. (And to make them more durable, you need to push them further outboard or use massive bearings!) Might work well with a lower duty cycle, or better bearing selection, but there will still be a limit to their durability.
All you say is true but these pitfalls can be avoided with a little bit of first principle engineering. Even the problem of the bearing thickness pushing the pedals outboard can be resolved by building the bearing inside the crank arm.
The big problem from a product design point of view is that you need a specialist frame to accommodate the optimum 30 minute drop that has been calculated by bio-mechanical analysis.
Non-round rings aren't exactly new either, despite shimanos attempts at putting everyone off....... they've got quite a following lately (last 6 or 7 years?) on the road scene.
Again true. Though it is interesting that all but one of the makers of such rings didn't calculate the correct position of the dead-spot but assumed it to be when the crank is vertical. Only when the academics pointed out this error did companies start to retard the crank relative to the major axis of the chain-ring. This is because the pedaling force of the leg has a horizontal component caused by the rider sitting behind the pedal axis.
I am concerned that studies into the effectiveness of non-round chain-rings invariably base their studies on a cadence of 90 rpm and focus on how much power is generated.
I would personally be more interested in seeing the results of low cadence studies that focus on bio-mechanical efficiency and effects on fatigue. Especially when hill climbing.
The reason being that at high cadences you can only spin slightly non-round chain-rings smoothly. With an extremely elliptical rings spun at high cadences it is also difficult or even impossible to keep up with the freewheel. So very elliptical chain-rings are best suited to slower cadences. Used this way they make hill climbing and riding into strong headwinds noticeably less tiring.
On the topic of these ideas "being around for an age", you are of course correct. But unfortunately, I can't discus the new ideas that are currently being prototyped by Cleland just in case they lead on to patent applications.
9/16" Suntour BMX MP-1000 pedals / 56 tooth TA 6-bolt chainring.(I'm not bothered if the teeth are worn or damaged)