On: 'Underwater bicycle' propels swimmers forward at s...

[uncertainrhymes]

That's a fair point. My (untested) assumption would be that it would be cumbersome and weird, and I wouldn't be 'swimming'.

If I were to guess at their motivations, it might be 'what could make me go faster in the water and also be enjoyable'? I'd try it out of curiosity, sure, but I'm pretty sure it wouldn't last beyond the novelty for me.

[DrammBA → uncertainrhymes]

Biking is definitely cumbersome and weird at the beginning, and it wouldn't be considered "running" by any stretch of the imagination.

[matt-attack → DrammBA]

A bike is just a way for runners to cheat.