Surprisingly enough, this makes acoustic bikes less carbon efficient per unit distance than electric ones, depending on the details of your diet. Of course, once the emissions are that low, this is more a curiosity than actionable insight (beyond the typical "less meat/dairy = lower emissions").

https://www.youtube.com/watch?v=HW5b8_KBtT8

"Acoustic" bike? What is this madness?

I thought you were autocorrected badly but I guess this is a term people use?