Honestly your awareness of 'the trap' definitely helped quite a bit - though there are some ways where your approach can still be improved. As a whole though, your work came out quite nicely as far as what I expect for this challenge.

Starting with your construction, you're doing a great job of tapering the ends of the wheel form (rather than just drawing a basic cylinder) to capture the illusion of an inflated structure. Most students here will generally just be working with a master ellipse template, so I don't expect a ton of flexibility, and what you had on hand definitely was enough for the purposes of this challenge. You are correct about the french curve - each tool has its purpose, and a french curve's is not to create ellipses.

I'm pleased with the patience and care with which you approached laying out the rims/spokes of your wheels as well - spacing them out evenly can be very challenging, and while upon close inspection there's a few that are a little off, you can't notice them at a glance, and that's generally what I'd consider to be plenty good enough. You've also played with a lot of variety here, which is always good to see.

So, getting to the matter of texture, I am very pleased to see that you did make a clear effort to work implicitly, to work with cast shadow shapes, and to resist the temptation to outline your textural forms and apply constructional techniques to such things - even if it was at least in part because you'd seen my critiques to others who had fallen in those traps. Learning from the mistakes of others is as valuable as learning from our own, in many cases.

There are however some ways in which you did not actually use cast shadows, but rather ended up using form shading instead. It's not all the time, but the fact that you end up jumping between them suggests that you're doing it unknowingly.

The easiest way to point this out is by actually outlining some of your textural forms as shown here. When the filled area is the side face of the textural form, that's form shading, because it's that surface getting darker from being turned away from the light source. Cast shadows are always entirely separate shapes that go on the surrounding surfaces, defining the relationship between the textural form and the given surface. Here's a diagram demonstrating the difference.

On the opposite side of that wheel, you're more likely to do it correctly - so it's just a matter of being more conscious of where you're putting that filled shape.

As for your question about that image at the end, what I just explained more or less goes over how I would tackle this - but I think there's something I should also clarify. The lighting in your reference isn't actually important, because we're not really trying to replicate it. The lighting in the reference instead makes it easier to understand the nature of the textural forms, so that we can then consider them in relation to our own invented light source in order to figure out where the cast shadows go.

Of course, usually that invented light source can be positioned in the same location as the one in the reference, but it's a matter of thinking about it in these steps - use the reference as a source of information, then solve the spatial problem based on what you know of 3D space.

Anyway, your challenge has indeed been done quite well, so I'll go ahead and mark this challenge as complete. Keep up the good work.