Boo. Kit, what girl is this?
I cycle the same path every day (and have occasionally noted you coming the other way). I'm always on the sniff for hot women, but rarely see any. There is one rather tasty brunette girl who always wears sunglasses and seems to have various 10k / marathon t-shirts on. Getting married next year so only up for the eye candy scene really.
In terms of asking her, why not come clean with:
"Hi, hows it going? (wait for reaction) I see you most days on my commute, think you look pretty/nice/hot/fast-on-a-bike, and was wondering if you'd like to go for a drink sometime? (wait for answer, no matter what it is, have your phone number written down to give her)"
… yeah I'm not amazingly great with women either.