In a flatland paceline with da boyz, barring excessive wind, 19-20.

In the hills, terrain much too variable for small-group drafting, a hard ride of 30-40 miles might average 16. Much longer than that, or at an easier pace, I'm more likely to average around 14-15. That's moving average. Using total ET could be a lot slower, depending on how often we regroup, whether we stop for lunch, etc.

Same bike. Same self. Different conditions. Don't worry about it.