Bmblbzzz wrote:... It might perhaps be easiest (least difficult) to put into practice by returning the bottom bracket to being an actual bracket beneath the frame rather than part of the frame as it has been for the last hundred years or so.
what, so it breaks? That is what happens to most dangly bottom bracket designs, unless they are beefed up to a ridiculous extent. There is a reason why more bikes are not made like that.
From the manufacturer's perspective the frame is a relatively cheap component, not worth compromising on once you have decided to have some kind of expensive gearbox/motor or whatever. For the user's perspective the frame is the heart and soul of the bike, and built into it are the choices for equipment that might be used. However this shouldn't come with a major weight, functionality or cost penalty. Otherwise we'd all be riding around of framesets with eccentric bottom brackets and swappable dropouts etc. As it is, manufacturers which have offered such features built into their frames have found sales are often less, not more, in good part because the frame is heavier and more expensive, but also because when being used in one mode it is clearly neither fish nor fowl.
If gearboxes and motors were such a good idea you wouldn't ever want to change them for something different...?