First of all, this is much better than your first intent. However, I don't love the pose of the girl. At first the robe confused me, and I couldn't find her legs. You can't really tell where her body ends at first sight, maybe because the colors of her boots are almost the same as the sky. I'd remove the boots all together, but you can make them shorter if you prefer, and also another color (or another color for the sky).
I'd remove completely the ostrich that's on the far right (only a small part of it is visible anyway); it's pretty distracting. About the girl's position, I'd put her closer to the ostrich's neck (I mean, move the saddle to about where the wing starts). The ostrich's wing looks weird right now, try to make it more feathery, just play with it some. Also, work more on the ostrich's tail.
You've done pretty good on conveying speed, I think. To that effect, you could make the girl's hair much longer and swirly and stuff. I think the ribbon's string (that's cut by the tail) should be longer and go over (not behind) the tail. I'm not really loving the tail right now, you could play more with it's position (look's somewhat stiff imo), or just remove it completely. Also, why does the girl have an adam's apple? If that's like "neck muscles" or something, I would make them more subtle cause right now they look like an adam's apple imo. Oh, and remove the tree branch; it takes away from the speed effect, seems like you just threw it in there to cover some space. You could also push her head downwards more, remember, she's in a race so she must use her body to guide the wind, not let it stop her (or decrease her speed), that's why jockey's crouch like that. Right now all the wind is hitting her right in the head, she'll probably lose the race lol.
Also, the girl looks as if she's slipping or sliding backwards. Make her grip on the "rope" (don't remember the word for it lol) tighter and higher up, right not it looks as if she's holding on to the ostrich instead of the ropes; and also make the ropes tense, not sloping downwards like that.
This is probably a long critique, and you're welcomed to ignore it, it's only my opinion after all, but I hope you find something useful
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