time trial 
noun
1(In various sports) a test of a competitor’s individual speed over a set distance, especially a cycling race in which competitors are separately timed.Karin will be competing in both the time trial and the individual pursuit in Athens....
- Mark Scanlon will contest both the individual time trial and the road race at the European championships in France next month.
- With her place in the road race long since secure, Cooke has yet to make up her mind about competing in the time trial, the event she came unstuck in at the Commonwealths.
2An exercise designed to test the time needed for a task or activity.If you think about the activity of completing a single reaction time trial you can imagine the sorts of mental processes you go through.