You should be fine on the metric if you did 45 miles. If you are looking to go farther, it's good to build up gradually--adding 5 miles to your long ride each weekend. This will make it more fun and you are less likely to get burnt out. I tried to jump 10 miles each weekend in a crunch to join my husband in a century--it eventually caught up with me. I did fine in the century, but missed two longer rides because of it. Just make sure you are still having fun