Drag racing seems simple at first, but the more you look into the sport where whoever crosses the finish line before the other wins, the more complicated and fascinating it becomes. One such example is called “spindle stagger,” or why top cars in drag racing don’t have front wheels that line up exactly.

Again, the principle of drag racing is very simple. You have a set distance and whichever car goes from start to finish before the next car wins. Something I had never given much thought to: where is the starting line, exactly?

Well, in drag racing you sort of need to have two.

We’re all familiar with how drag racers are started off of a tree of lights, but what triggers those lights to know that you’re in place are two sets of staging beams that shoot perpendicular across the track. Trip the first beam and you’re “staged.” Then the lights can go. Trip the second and that’s where you’ve officially started.

Because I’m not a drag racer and I am only vaguely confident that everything I’m getting out of this is correct, I’ll cite a more technical explanation from drag racing history site :

The “staging light” trigger beam projects directly across the starting line, and is part of two separate circuits. As a wheel enters and blocks the beam, interruption of the circuit causes the “staged” light to illuminate on the tree. Later, as this wheel rolls across the starting line on a run, it allows the staging beam to once again illuminate the target photocell across the lane. This shuts off the staging light and starts the e.t. clock.

What never occurred to me is that drag racing is so competitive, even the space between the two timing beams is critical. This came up in a recent Hoonigan video, in which the crew goes to Don Schumacher Racing and practices running for reaction times with funny car driver Tommy Johnson Jr.

In the vid they go over how you can stage shallow or stage deep, either juuuuuuust tripping the first beam and then having more room for the car to accelerate or tripping the first beam late, rolling a bit past it and then getting what the beams would sense as a faster reaction time.

It’s at , or at 18:30 if you want to see the whole segment. Ignore the GT-R in that image and skip ahead and you’ll get to the drag racing, have no fear.

“Deep and shallow staging... You’re actually leaving at the same time,” Tommy Johnson Jr. explains. “But if you rolled it in a little further, it’s going to come out of those beams quicker. So you’re reaction’s gon’ be quicker. Makes the driver look like a hero. But, it’s going to slow the elapsed time down, because you’re not quite getting a rolling start before you cross the start.”

Remember, this is a space of six inches we’re talking about here. For cars that make 11,000 horsepower.

Johnson Jr. goes on to note that a few inches at the start of the race could mean a couple of feet at the end of it, and a worthwhile potential advantage. But it comes with tradeoffs.

“The crew chief hates it,” he says. “Because it’s going to kill his e.t. We need lane choice, kills that. We might lose lane choice. So you live or die by it, but you get the win.”

So you can gather how there’s pros and cons of staging shallow or staging deep, of having your front wheels way ahead of that first staging beam or only just after it.

But! There is a way to do both. This is what’s called “spindle stagger,” meaning that the front spindles (what the wheels mount to) are set up with one wheel ahead of the other. That way the car stages both deep and shallow at the same time.

The best explanation of this, naturally, comes from the midst of a pissed-off argument on an internet forum, which is about as terse as people get. This is from :

Stagger in a the front tires gives the starting beams a larger target that will give a longer roll out. What will this do? This will give your car a running start at the starting beams.

had a slightly different explanation, with a few more typos, which I shall choose not to alter:

Stager is determined anytime after 10pm on any givein raceday supplied w/ enuff alcohol and reaction time is the ability to control the shakes from the nite before.

The history of it is fun, as Tommy Johnson Jr. points out to Hoonigan in their video:

Back in the day, guys figured out if you could stagger the front wheels so you stage ’em with [the front one] and as you leave the other one’s trailing behind it, the beam doesn’t start until the last wheel comes out of it. So you’re getting a huge advantage. You’re getting the car rolling before you start the clock. So they put a kibosh to that.

Spindle stagger, like all cheat-ey aspects of racing, is tightly regulated to the fraction of an inch, but usually sits between one and two inches allowed depending on what class of drag racing you’re doing.

I thought it would be easy to find a good photo showing spindle stagger, but it’s annoyingly difficult as drag cars twist up a wheel into the air when they launch, making any perspective look off. This plays into wheel stagger as well, as We Did It For Love also notes:

Front wheel stagger is to give the car additional rollout before the beams detect that the car has moved. Because torque has a tendency to lift the left wheel first, it is normally the leading wheel.

So this is why the left side of drag racing cars is usually longer than the right, if by only an inch or two. It’s a fascinating little aspect of the sport I had never really considered, a grey area that’s wonderfully emblematic of how auto racing really works.