Originally Posted by Deman Llama

This.

As formerly naive female who used to think that guys hung out with girls because they were really interested in what they have to say...

Male acquaintances say that guys only hang out with three categories of girls:
1) Girls they want to have sex with
2) Girls they've already had sex with and would have sex with again if given the opportunity, and
3) Ugly girls

OP, you're attracted to the girl. You're attracted because she rides. If she didn't ride, you wouldn't have any occasion to spend time with her, but the fact that she rides makes her attractive even in a (currently) non-sexual way.

So long as you realize this and control it, you're fine. And so long as everyone is honest their respective partners, you're fine.

(As far as my male acquaintances, having never slept with any of them, I don't know whether I was the chick they wanted to have sex with or the ugly chick. Not sure which would be worse....)