[dcb]

There are already detents for neutral and the other gears, it is a ball on a spring riding on a drum of sorts. Trick is figuring out how/where to add more detents so you can feel it with your toe.

Since the bike HAS to fully disengage one gear before engaging another, there is such a position between every gear, but the vetter guy just added one between 4th and 5th (top), perhaps with a dremel and careful analysis and complete disassembly.

I've accidentally found these neutrals many times, especially when learning a new bike.