Group Ride w/rubber band, speed too high

For the 2nd time in as many weekends, we’ve done a group meet-up with the rubber band on. After some riding, and despite out power data being correct (3.5-4.5 W/Kg climbing), we have being moved toward 46 kph, climbing, descending, flats, the two of us climbed the Epic KOM Reverse in sub-10 min at 3.5-4 W/kg. Then, as soon as one of us leaves, the issue is resolved. What is going on? How can we fix this?

A post was merged into an existing topic: Meetup Speeds Incorrect with Small Groups