how about Mountain Bike or conventional bike? And then eMTB or eBike?
We don't call non-electric cars "acoustic cars".
I do understand where you are coming from on a need to differentiate. And it isn't a criticism of your writing (it's a criticism of the industry), I just feel that calling them "acoustic" or "analog" comes off as marketing schtick or trying hard to be cool. It evokes too much of an analogy of guitars, maybe that is a function of who Specialized used to popularize the term.
Damnit, I'm going for a ride on my bike powered 100% by my legs!