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What is Double-Elimination
and How Does it Work?

This is a question that arises often when Cub Scout Packs begin planning for their Pinewood Derby, Raingutter Regatta, or Space Derby. Whenever scoring the race comes up, double-elimination is often mentioned. It seems like everyone has heard the term "double-elimination" before, but when it comes to finding someone in your pack who actually knows how it works and can set one up, you may be out of luck. The purpose of this discussion is to help the various scout organizations that find themselves without someone who is familiar with the double-elimination method, by explaining what it is and how it all works.

There are many other ways to judge a derby race besides double-elimination, such as single-elimination, lane-rotation, and round-robin, to name a few. However, this discussion will focus on the double-elimination method, or more specifically, the "Ladder" method of double-elimination. Although this explanation refers to Pinewood Derby racing, it would of course also apply to Raingutter Regatta, Space Derby, or any other kind of "Derby" racing.

Double-elimination is probably the most commonly used method for judging a Pinewood Derby. In a double-elimination Pinewood Derby race, cars remain in competition until they sustain two losses. After the second loss, cars are eliminated from competition. This method is not as definitive as actual timed races for determining the fastest cars and it does not accommodate any imperfections in your track from lane to lane, but it is relatively easy to manage and there are no times to keep track of. For most packs, especially large ones, double-elimination is also preferred over the round-robin method or the lane-rotation method, both of which usually require many more heats and a lot more time.

In a double-elimination race the only place that matters in each heat is first place, regardless of the number of cars in the heat. The first place winner in each heat advances to the next level. All the other cars in the heat move to the losers bracket, or if they are already in the losers bracket, having already sustained 1 loss, are eliminated. Not having to keep track of second, third and fourth places in each heat is one of the major advantages of double-elimination.

The easiest way to keep track of winners and losers in a double-elimination race is to construct a "Ladder," such as the one below.

Constructing a Ladder

The above is an example of a double-elimination ladder for a 24 car race on a 3 lane track. Using this example as a model, you can construct a ladder for any number of cars racing on any number of lanes. Determine ahead of time how many cars will be racing to construct your ladder. Just remember you must have a Winners Bracket and a Losers Bracket, and to group your heats according to the number of lanes on your track. Also, you must label each heat in the winners bracket so that losing cars may be properly placed into the losers bracket. This is easily accomplished by using letters of the alphabet. See examples below.

When a car loses it is placed into the losers bracket according to its corresponding letter. Cars advancing in the winners bracket take on new assigned letters. Notice in the example below that the corresponding letters in the losers bracket are placed so that the competitors will not be racing against the same cars they raced against in the winners bracket (at least until much later if they continue to advance). This is a key factor in running a fair race and should be maintained as much as possible when constructing your ladder.
Running the Race

Before the race begins you must number all the cars for purposes of identification. This can be a sequence of numbers or random numbers, it doesn't matter, but all cars must have a different number. It is usually best to select the cars at random for numbering. When all the cars are numbered, write their numbers into the starting column in the Winners Bracket. When racing begins, call out the numbers of the cars in the first heat. When the heat is over, place the number of the winning car into the next column in the winners bracket and place the numbers of the losing cars into the losers bracket (first loss) according to their corresponding letter. When this is done, call out the numbers of the cars in the next heat in the column. Continue in this fashion until all the cars in the column have raced. See example below.

Now that all the cars have raced one time, you have the option of continuing to race cars in the winners bracket or jumping to the losers bracket. It doesn't make any difference in terms of the final outcome. Just remember you can't start a race in a losers bracket column until the numbers in the column are complete, based on the outcome in the winners bracket. In general, it's best to begin racing a column in the losers bracket before all the columns in the winners bracket are completed. This makes the race more interesting for the boys whose cars are going into the losers bracket and more dramatic for the boys (and spectators) still racing in the winners bracket.

Racing cars in the losers bracket is done the same way as in the winners bracket except that only the winners will advance and continue racing. All cars losing in the losers bracket are eliminated from competition (second loss). See example below.

The championship will be determined when the winner of the winners bracket races the winner of the losers bracket. However, keep in mind the following regarding this last race:
  • If the losers bracket winner beats the winners bracket winner, then they must race again for the championship (on different lanes preferably). This is because the winners bracket winner has not yet sustained a loss and must lose twice to be eliminated (double-elimination).
  • If the winners bracket winner beats the losers bracket winner, then the losers bracket winner is eliminated, having lost twice, and the winners bracket winner is champion.

In other words, the losers bracket winner must beat the winners bracket winner twice to become champion, but the winners bracket winner must beat the losers bracket winner only once to become champion.

The following is an example of a completed 24 car race on a 3 lane track, so you can see how all the numbers flow on the ladder. This race would consist of 26 or 27 heats (depending on the outcome of the championship race) and the time required would probably be from 45 minutes to an hour.

The trickiest part of any double-elimination race is managing the flow from the winners bracket to the losers bracket. By reviewing the preceding material and studying the examples, hopefully, you will be able to construct your own ladder for a successful race.

Summary

When running your race, follow these guidelines:

  • Determine how many cars will be racing ahead of time.
  • Construct your double-elimination ladder.
  • Number the cars before the race.
  • All cars start in the winners bracket.
  • Only the first place finisher in each heat advances.
  • Losing cars go to losers bracket (first loss).
  • Place cars in the losers bracket according to their corresponding letters.
  • Cars which lose in the losers bracket are eliminated (second loss).
  • Complete all the racing in any given column before going to the next column.
  • Winning car in winners bracket races winning car in losers bracket for championship.
  • Losers bracket winner must beat winners bracket winner twice for championship.
  • Winners bracket winner must beat losers bracket winner only once for championship.

Double-Elimination - Caveats

A double-elimination race can accurately determine only the first and second fastest cars (assuming all lanes are the same in terms of speed). To accurately determine the third fastest car you would need to have a triple elimination race. In a double-elimination race, a third place finish can be awarded based on the final heat in the losers bracket (third place going to the loser of this heat, or to the second place finisher if more than 2 cars in the heat) but this place is subject to the "luck of the draw."

For example, if by chance the actual first, second, and third fastest cars were in the same heat in the winners bracket, then the second and third fastest cars would go to the losers bracket, having lost to the fastest car. Then, if by chance, the second and third fastest cars met in the same heat again in the losers bracket - other than the last heat (which is possible) - then the actual third fastest car would be eliminated (second loss) by the second fastest car before the last heat in the losers bracket. This means that if your pack will be awarding a third place using the double-elimination method, it is possible for a car to win third place which is not the actual third fastest.

A triple-elimination ladder can be constructed by adding another bracket, a double losers bracket. All cars which lose in the losers bracket (all cars with 2 losses) would go into the double-losers bracket, and the winner of this bracket would be the actual third fastest car (once again, assuming all lanes are the same in terms of speed). However, running a triple-elimination race adds a degree of complexity that most people don't want to deal with, especially in the chaos that ensues during most Pinewood Derbys.

In reality, there is no way to know ahead of time which cars are the fastest and what heats they will be in, so the above example might be illustrating a moot point. Moreover, using a carefully constructed ladder, the third place finisher in a double-elimination race will, more often than not, be the actual third fastest as well. I only mention it here so that you are aware of the fact that a double-elimination race, by definition, will determine only the actual first and second fastest cars, and that any places beneath those are somewhat a matter of chance. And as I stated earlier, all of this is assuming that all the lanes of your track are the same in terms of speed. If the lanes are significantly different from one to the next, then the only way to accurately determine the fastest car would be to race each car in each lane of the track, time the races or award points according to finishing place, and average the times or tally the points to come up with an overall time or score (lane-rotation method).

Final Thoughts

Our pack is willing to live with the "luck of the draw" when awarding third place (and sometimes fourth place) so we stick with the less cumbersome double-elimination method. And because double-elimination doesn't account for any speed differences among the lanes, and no track has all lanes identical in speed, all the boys are subject to a certain degree of luck anyway. Plus, we feel this is more in keeping with the true spirit of Pinewood Derby Racing - they're all winners.

Another reason our pack uses double-elimination is because it is one of the quickest and most efficient methods for completing the competition. In the past our pack has had as many as 80 cars racing on 6 lanes! Try using lane-rotation with that many cars and see how long it takes. Everyone enjoys the competition but with that many cars it can drag on a bit if things aren't run efficiently. One of the things we like to do is to allow time for "free racing" which is something all the boys really seem to love. We try to structure the event so there is plenty of time for this after all the competition.

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