Back in post #1 it appears that this is a "twosome", not a cluster. And it seems like only one has the lagging behind problem. When I ride with one other we tend to stay side-by-side so that conversation is easier. Of course, being in better shape allows conversation instead of hard breathing. Also, we do not hold that 25MPH pace like some groups do.Each bike would need to be equipped with transmitters and reflectors. Whomever is in front, and that changes when one tires. Or when one lags behind.
Alternative solution:We are good at not rubbing tires, but I fall off the back sometimes and have a little pride thing not to shout out. My wife is in much better shape than me!
I was very pleasantly surprised at the overall experience of riding one of these. Quiet, smooth, well engineered. Much easier than I expected because the integration of the hub motor is so well done. Nothing jerky or clunky about it.My buddy has a Specialized brand e-bike, I think it's this one with the front suspension. It's a higher end brand, a lot of fun to ride. You can adjust how much help the motor gives you and you can fly along without much effort if you turn it up all the way. They claim 80 mile range, I'm not sure if that's what my buddy gets but he rides it all over town. You can pedal as hard as you want so you can still get the workout if you want it, just at a significantly higher ground speed than a non-assisted bike.