The achilles heel of rear mechs being in the line of fire often comes up but if they were vulnerable we’d have ditched them years ago. It’s a problem that doesn’t exist.
They are vulnerable, but the issue manifests itself relatively rarely. I mean across all gear-dangler equipped bikes.
Mech smashing issues primarily affect off-road riders and mostly those participating towards the “Gnarr” end of the scale.
The problem that most alternative solutions to derailleurs face isn’t necessarily technical, it’s mostly market based, your main target group are a niche within a niche still. And when that solution potentially comes at a substantial premium converting interest to sales is even more challenging. If it could be sold in other areas it would have a better chance perhaps.
He’s done the right thing IMO; develop the idea into a working prototype, file patents and setup a company to act as the commercial side to his interests, then go looking for an established manufacturer because he’s not only pushing a drivetrain idea, it’s a whole bike essentially, and he won’t have the resources to turn that into a viable business on his own…
It’s clever and all that but man, just give me a 5 speed gearbox FFS.
Ta Da!*
(* Out of stock/probably not enough range/probably not quite what you had in mind).