Thud wrote: I am still of the opinion that a proper "cush" mounting of the larger sprockets will go a long way adding durability to these built for human power mechanical systems.
I don't disagree that cush in the drive system for most of us is a great idea. The way that is achieved and how much there is would be the issue. For gwhy, no cush would be best as he wants to trials ride and wants response immediately without shock loading anything.
For the rest of us, drive train lifespan would be increased if we could have a little cush with out shock loading anything. If there was none, we would probably see a lot of broken chains, sprockets and mounts, and bent shafts. The problem with freewheels and free hubs, is they have prawls that catch and create a shock load. If the hub and freewheel are not both engaged when power is applied, then a quick application of power will shock load the system as the the prawls engage. With a freewheel and free hub you get double the shock load or the chance for two shock loads.
So to get that cush, it could be a rubber mounted sprocket, or maybe there could be enough in the tire as it will flex as it gets grip with the ground. I think after ridding my bike with only a free hub, that driving the free hub direct with the motor will be the best option if you don't want to pedal alone with the least drag possible. The double freewheel is great for those that want to be able to pedal like a pedal bike and motor when they want to motor. It all depends on what you want to do with your bike. gwhy, may want instant power with with no cush, but may break other parts of the drive train.
Well, that was more than I've said in a long time. I guess I'm saying, think about what you want from your bike and build to suit. There isn't one solution for all. But come up with a cushined sprocket mount would be the cats pajamas (good for those that didn't get that).