Most races do not have a time limit. Sign up, show up, and don't give up! AROO!
However, longer races may have cut-off times for safety concerns.
If this is the case, cut-off times will be posted on the event page or the Race Day Program the week before the race.
Be sure to check your events Race Page periodically for updates and changes, as you are responsible for knowing the cut-off times for your event.