I agree with you, virgohippy and MrYum and combine them all.
Talk to her like only a Mom can. Drive her to school for a couple days and point out all the other kids riding their bikes. Since its the weekend go on a bike ride with her reminding her how much fun it is but definitely get her on that bike. That alone will help her move forward even if she does not think so.
Wish you the best of luck
