Pinewood derby heat chart

Say how many cars and how many lanes. Every car gets one run in every lane, the pairings are spread as widely as the arithmetic allows, and the schedule, the race cards and the tally sheet all print.

How the lane rotation is built

Number the cars and give each lane an offset. The first heat puts the car sitting at each offset on the line, the next heat moves every lane along by one car, and after as many heats as there are cars the ring has turned all the way round. Read it car by car instead of heat by heat and each lane names exactly one heat.

That is the guarantee, and it is worth stating precisely: every car runs in every lane exactly once. Not roughly once, and not once on average across the pack — once, on a chart of any size in the range this page covers, with nothing left over and nobody quietly short of a turn in the quick lane.

The offsets are where the work goes. Any distinct set of them balances the lanes, so what separates a good chart from a bad one is who ends up racing whom, and the offsets that look most natural — one, two, three, four — are precisely the ones that put the same two cars beside each other over and over.

Why the lane a car draws decides races

Tracks are not symmetrical. A lane picks up a crown in the wood, a guide rail wears smooth, one gate pin lets go a thousandth of a second early, and any one of those is worth more than the gap between the two fastest cars in a pack. A lane advantage of a couple of hundredths, measured across an afternoon, is completely ordinary.

A single run therefore says very little about which car is quicker. It says which car had the better lane, plus noise. The only way to take the lane back out of the result is to give every car the same lanes, and that is a chart rather than a rule — which is the entire reason derby scheduling software exists.

Rotating also removes the argument, which matters more than it sounds. Nobody has to be persuaded the track is level, because the chart makes the question irrelevant: whatever the quick lane was worth, every car has had it exactly once by the end, and the standings are comparable without anybody trusting the carpentry.

Running the day off the printed chart

Three sheets come off this page and they do different jobs. The schedule goes on the wall beside the track, the race cards go to the racers so nobody has to crowd the wall to find out when they are next, and the tally sheet goes to whoever is writing down finishes. Printing only the first is the commonest reason a well-planned derby still runs late.

Call two heats ahead all morning. A heat takes about ninety seconds once carrying cars back and lining them up is counted, and almost none of that ninety seconds is the race — so the way to finish on time is to have the next set of cars already standing at the top of the track when the current one crosses the line.

If a car breaks, leave the chart alone. Score the heats it misses as no-shows and let the rotation carry on, because renumbering a chart halfway through destroys the lane balance for every car still running and there is no way back to it short of starting the morning again.

Common questions

Every track width

• 2 lanes
• 3 lanes
• 4 lanes
• 5 lanes
• 6 lanes

The other tools

• Bracket generatorGenerator
• Random drawGenerator
• Double eliminationReference
• Blank bracketsPrintable