You did great. I agree with PPs that the grown-up comment was really unreasonable. If she persists, I don't think it rude to say "I really love bicycling and don't wish to discuss it any more."
Your clarification about the work that needed to be done and why a quote could be done over the phone makes sense. I was thinking more of a "my car is making a funny clunking sound, how much is it going to cost of fix?"
Because that is totally what I would do!