We all have this moment.

I'm not sure asking someone to draw "a helicopter" or "a bicycle" (inherently an abstraction) is a good way to get non-nonsense simplifications. It's like asking for "a face" and expecting something that isn't cartoonish? Also, I doubt all non-aphantasiacs can draw tolerably. That said, I do sort of assume it's a spectrum, and that there's a similar-ish 1-10% of people on the far end who visualize very well.

Perhaps if you ask them to describe their first bike in as much detail as they can?