It would be nice if members could declare each other as VTPs (virtual training partners). VTPs can race against each other without being online at the same time.
When you choose a route you can add one or more of your VTPs and you can race against one of their recorded rides on the selected route. At least for Strava-Users it should be fairly easy to replicate previous rides.
VTP avatars do not need to be visible for the other real riders, they could be red “ghost riders” that are just added to the world as the blue “ghost riders”.