Try to draw a men’s bicycle, by heart before clicking on the link. Can you do it?
Very cool. Yes, I’ve got a box of metal tubes in a corner of my office that are supposed to be a track frame and maybe will be one day, so I can and have many times. But I especially love that first rendering, from the drawing by Anna, with the springer leather saddle and the wooden rims. Add maybe one more tube and it might even be ridable like that.
I’ve tried, but seems like I made one of failed bicycle. 
Now I spend 1000’s of hours on a bicycle, and even did some frame-building myself, so even my angles will be pretty accurate.
But yes, I’m often amazed how many pro painters, graphic designers and alike artists are uncapable of drawing any logic (just like on the examples, which I often can’t understand why they draw this).
I love how so many of the drawings shown have unicycles in them! You know, unicycles, with an extra wheel attached? One looks essentially identical to a “bike” you could buy in the 90s. And then the computer illustrations he made were beautiful.