Could you go out on your bike at a time and on a route where you know she'll be one day and strike up a conversation that way?

I know I'm much more open to being approached by other cyclists who look like cyclists -- I'll ride with strangers I meet when I'm out, but I don't know if I'd feel comfortable getting a note. I guess my general suggestion is try to encounter her in person, preferably as a person who has an obvious shared interest with her, and then explain from there.

Another idea - maybe post something on the Craigslist Missed Connections for your city?

And I second the previous comment - I love the thread title!