What Irulan and Bicilista had to say. Don''t sugar coat the "bad" news. Maybe they are realize they are in way over their head with your bicycle ability and not sure how to break the news to you.

Just tell them that you enjoyed their company but training ride is just that and you have a training goal. And don't show up with a 40 pound beater bike so that you can ride slowly with them. It sends a wrong message. If you have a kit wear it. Ride your regular training bike. They'll see that your intended ride is not the same as them. They will understand.