During a group workout today a rider with apparently similar abilities as mine became stuck riding next to me. We rode side by side for the entire hour long ride. Although my cadence and power remained relatively constant my speed would rise and fall constantly by 15 mph or more every couple of seconds and my avatar would continually slightly overtake and then drop slightly behind my partner. My partner’s avatar seemed to proceed with a steady pace. Nothing else with the ride was affected. Also, because of an initial error when logging in, I , and I suspect my partner, joined the ride about 2 minutes , or so, late.