Did he mean the "zero carbon" that was used to make the bike? Cos it sure as hell isn't zero. Or were the pannier and saddle bags "zero carbon?" No, didn't think so. The clothes he's wearing, including specialised cycling suits? Nup.
Oh! Oh! I get it! Zero carbon in fuel! Yeah! That's what he meant. Except. That he has to eat, and food has a fecking huge carbon footprint of its own.
I think what he's trying to say is that he's going to (for unfathomable reasons, as everything you could want is right at hand in your neighbourhood in this modern world) ride around for his own amusement, and feel a little bit better in himself for only releasing fart methane while on the ride.
Except possibly for the bits where he has to ferry or fly himself and the bike across oceans he can't actually ride through.... Even sailboats had to be made you know - like bikes and bags and clothes and foods.
The only way to have NO carbon footprint is to die and evaporate.
And this is what's wrong with so many green efforts - they want to make you a greener person, as long as you buy their product, buy into their scheme, keep that money going around. And when you come down to it, money has the worst carbon footprint of anything on this world.