Any member has access to add an event to the calendar.  If you are calling a ride, just open the calendar in Google Calendar, and add your ride information.

Use this ICAL address to permanently add this calendar to your phone or desktop:

https://calendar.google.com/calendar/ical/21u7tfll8g32c6630878l0hg7c%40group.calendar.google.com/public/basic.ics