Through the miracles of the internet, I found the Brussels Road Cycling group who seemed like a good match for me (contact the organizer to get in on their WhatsApp group chat). Averaging 24kph (~15mph) I figured I could maybe keep up with them since I got up to 16mph during Cascade Training Series (CTS) last spring. Unfortunately, what I didn't remember is that I really struggled when we averaged 16mph, and I hadn't seriously ridden a road bike in half a year.
So, I left them at around 15km into the 60km ride, not wanting to hold them back, and happy to go at my own slower pace. I also had some mechanical issues I needed to address. Luckily, at 15km there just happened to be a castle along the route.
Bonus shaggy horse!