Hi Flybye

Welcome to TE. I think 64 is definitely doable. I rode the ULCER a few years ago as my first ever organized ride. I had not even trained and my max miled as probably 20 miles. I had no problem riding the half century...well I was a bit sore the next day. But with rest stops every 15 miles or so, there was time to get off the bike, stretch eat. If you find a trianing plan online and ride different mileage during the week, I think you will be fine for the metric by June 2nd. And remember, its a ride, not a race. You can take as long or as short as you want to to ride it. The fab guys at BBTC won't leave you out there alone on the course. You'll also probably end up riding with other ladies at your speed. Go ahead and register for the longer ride. Let that day determine how far you actually go. LRRH is a great first organized ride.