My mom and I did their 4:00 PM E-bike tour this past week. It was a great experience and our guide…read morewas excellent! I would recommend doing this tour on your first day/afternoon in Madrid so you can get acclimated to the city and see some of the main sites.
Our guide, Fran, was knowledgeable, personable, and animated. The background he provided at each of the sites was interesting and helped us learn more about Madrid and Spanish history. He also had great tips and recommendations for where to go in Madrid.
The tour was about 10-15 people I'd say. It was a good size to command enough attention to safely drive on the road in a lane but have everyone stay together. They provided a water bottle, helmet, bike. Fran even took us to a special "surprise stop" at the end (churros!).
With the E-bike, you could adjust the assistance and you still pedaled to make the assist go, but it was a good choice to have some assist as there are hills and you don't want to worry about having to keep up on going when you're driving in a lane on the road.
The shop also has bikes, roller blades, and skate/penny boards for rent.