Enduro is a form of Mountain bike racing in which there is a greater proportion of downhill sections, which are timed, to uphill and cross country sections. This aims to test rider's technical bike handling skills as well as providing endurance and climbing. Riders race multiple Enduro stages; the winner is the competitor with the lowest aggregate time. Riders are not timed on the transfer stages, those used to get riders to the start of the next timed or "special" stage. It is these transfer stages that allow for the lighter side of this sport to come out. It offers you time to chat it up with your friends as you make your way back to the top.
Enduro differs from XC cross-country cycling racing, which historically has more emphasis on cardiovascular fitness and less emphasis on technical ability, or to pure downhill cycling racing formats, which may contain little to no climbing or cross country skills. Enduro's 'All Mountain' discipline therefore favors riders with a breadth of skill, on multi discipline cycles; lightweight XC bikes may lack sufficient suspension travel for fast downhill control, whilst full DH bikes may not allow a rider to climb the uphill sections. If you want to learn more about enduro, check out this article on pink bike.com: Beginners Guide to Enduro, What the hell is it?
Generally, after you've registered there is a brief rider meeting to go over some rules, then you ride to the first special stage. Sometimes the race organizer has the pro riders go first, sometimes they go last. The transfer climbs are often a casual pace where you can catch up with old friends. Once you get to the starting line for the first timed stage, it's go time! Just you and the trail...how fast can you go? After you cross the finish line for that stage there's a chance to catch your breath then ride to the next timed stage to do it all over again. Most enduros will have 4 or 5 timed stages of varying length depending on the terrain.
The beginners guide to Enduro Racing #1 - Basic questions http://enduro-mtb.com/en/the-beginners-guide-to-enduro-racing-1-basic-questions/
Here we'll cover some basics of what you should carry with you during a typical enduro race. Water, tools, tubes and food are common items that an enduro racer will carry with them to make it through the day since we are required to be self-sufficient. If you don't carry a multi-tool on rides now then you better get one. You never know when your chain is going to break on you and being able to fix that out in the woods is the difference between keeping it fun and having a bad day. Below is a basic list of some items that you should carry with you on race day.
Timing can be done by hand where start times for each rider number are written down at the start and finish of each stage or it can be done using a chip timing system. A lot of enduros, like the Trans-provence 7 Day enduro, use the SPORTident system which uses a timing chip and a reader at the start and finish of each stage. Below is a video of how the SPORTident system works.