Tracktivity provides a great feature for this - Race Control. It is a communication channel for important messages from Partner Venues. Typical examples of Race Control messages include:
Short notice event date/time changes
Important track news
Whenever a Race Control message is posted, the message will be published in the Race Control window for all users following your track. In addition, users will receive a corresponding push notification to their device.
Tracktivity does not employ an algorithm which determines what appears in users timelines and what doesn't. All messages posted into Tracktivity will be delivered to the users.