In 1873, Jacob Davis and Levi Strauss received a patent for what was, for everyone who heard it, a Good Idea.

The idea was rivets. Specifically: small copper rivets placed at the stress points of denim work trousers — pocket corners, the base of the fly — to stop them tearing. Davis had noticed the rivets on horse blankets in his workshop and made the leap. The trousers held together, but word spread. The patent was filed. The rivets were doing exactly what rivets should do.

For nearly seventy years, one of those rivets sat at the base of the fly on every pair of Levi’s produced. It was called, with the directness that characterises industrial design: the crotch rivet.

It was removed* in 1941.

The reason, widely reported and enthusiastically repeated by Levi’s own marketing department**, is this: the people wearing the jeans were cowboys. Cowboys, on cold nights out on the range, would crouch near a campfire to get warm. The copper rivet, being copper, would conduct the heat of the fire with considerable efficiency and transfer it to the area of the body it was closest to.

Which was, as the name suggests, the crotch.

There were complaints. The rivet was removed. Reinforced stitching — bar tacks — took its place.

The rivet had a purpose. The rivet worked. The rivet was, under a specific set of real-world conditions that nobody had considered at the design stage, a source of significant and intimate discomfort.

This is a problem that has nothing to do with rivets.

_{*U’k’shem she-nichnas la-brit, ken yikaneis l’Torah, l’chupah, u’l’ma’asim tovim}

_{**Wikipedia records that the crotch rivet was officially removed to comply with wartime metal conservation rules under the War Production Board, and that the campfire story — though widely repeated, and encouraged by Levi’s own marketing — may be apocryphal. This is simultaneously slightly deflating and entirely appropriate. It is worth noting, however, that the Japanese denim community — which has studied the history of Levi’s construction with what can only be described as archaeological seriousness — tends to treat the campfire story as at least partially credible, on the grounds that it is consistent with the kind of real-world feedback that drove many other design changes. The truth is probably that both things happened: the war gave Levi’s a reason to remove the rivet, and the cowboys had already given them several.}

The gap between the desk and the campfire

Every design decision — every strategic decision, every marketing decision, every product decision — is made somewhere. Usually a room. Usually with a table in it, and people around the table, and a problem to be solved.

The room is not the world.

In the room, the rivet is obviously correct. It reinforces a stress point. It prevents tearing. It is small and cheap and does its job invisibly. The person who proposed it was not wrong. The people who approved it were not wrong. The patent office that granted it was not wrong.

Nobody in the room was a cowboy crouching next to a fire*. Nobody in the room was the person who would actually wear the thing, in the conditions the thing would actually be worn in, encountering the precise set of circumstances that would reveal whether the thing worked as intended or merely as designed.

This is not a failure of intelligence. It is a structural feature of how decisions get made. The campfire is always absent from the room. The question is whether anyone thinks to put it there.

_{*Unless it’s a David Lynch room}

The marketing version of this

The crotch rivet problem appears in marketing with regularity. It usually looks like this: a decision that is clearly correct in the context in which it’s made, deployed into a context that turns out to be different in one or two important ways, producing results that are baffling until you go and look at where the actual users are sitting.

The pop-up that asks for your email address thirty seconds after you’ve arrived on a website.* In the room: a mechanism for growing the mailing list, timed to appear before the visitor has made any decision to leave. The logic is sound. The campfire: every person who has ever arrived on a website with a specific question, been interrupted by a form before they’ve found the answer, and left. Probably while swearing.

The automated follow-up email sent three hours after a prospect downloads a piece of content. In the room: a nurture mechanism, triggered by a signal of intent, maintaining momentum. The campfire: the prospect who downloaded the content at 11pm out of curiosity, wakes up to an email that implies a decision is imminent, and feels the relationship has moved faster than they agreed to.

The customer satisfaction survey sent immediately after a support call. In the room: a feedback mechanism, capturing sentiment while the experience is fresh. The campfire: the customer who has just spent forty minutes trying to resolve a problem that shouldn’t have existed, and is now being asked to rate their experience before they’ve had time to decide how they feel about it.**

None of these are bad ideas. All of them are right in the room. The campfire — the actual moment of encounter, with the actual person, in their actual context — is absent. And the campfire is the only thing that matters.

_{*Autoplay video on websites follows the same logic. Somebody, somewhere, had data suggesting that video content drove engagement. They were probably right in the context the data was collected. The autoplay was the rivet: a sensible mechanism, wrong context. The context, in this case, being every website visited by a person who was not expecting to suddenly be shouted at.}

_{**The QR code on the restaurant table is the modern crotch rivet. (There’s a pull quote for you) Genuinely solves a real problem (contactless menus during a pandemic), deployed with confidence, now used in contexts — the upscale restaurant, the pub with unreliable signal — where it creates more friction than it removes. Nobody has removed it yet, but the reviews are in.}

Why it keeps happening

There is a version of this problem that’s about not thinking hard enough, and a version that’s about thinking hard in the wrong place.

The first version is the simpler one: the decision gets made quickly, nobody asks what could go wrong, the rivet goes in. This happens. It’s fixable with a habit of asking the question.

The second version is more interesting and more common. The people in the room do think hard. They consider the use case. They consult the data. They may even run a focus group.* And the thinking is good, but it’s thinking about a model of the user — an abstraction assembled from analytics and assumptions and the occasional survey — rather than about the actual person, in the actual moment, with the actual campfire.

The model is always missing something. Usually several things. The model doesn’t get cold at night. The model doesn’t have a deadline that means they’ll abandon a slow page after four seconds. The model doesn’t have a previous bad experience with a similar product that makes them read your perfectly reasonable automated email as presumptuous. The model is in the room. The user is at the campfire.

The gap between the model and the person is where the rivet lives.

_{*This is the question that focus groups are theoretically designed to answer, and in practice often don’t — because focus groups ask people to evaluate a thing in a context stripped of all the contextual factors that determine whether the thing works. The rivet tests well in the room. The campfire isn’t in the room. And if there is a campfire in the room, the room will quickly be missing a focus group}

What to do about it

The short answer is: go to the campfire.

Find the actual person, in the actual context, experiencing the actual thing. Not a representative sample in a controlled environment — the specific, awkward, edge-case human being who is going to encounter your rivet in precisely the way you didn’t imagine.

This sounds obvious but is surprisingly rarely done. The room is easier to stay in. The room has good acceptable lots of coffee and a clear agenda and people whose opinions you broadly know in advance. The campfire is remote and inconvenient and produces information that occasionally requires you to redo something you thought was finished.

But the campfire is also where you find things out before the product launches rather than after the complaints arrive. Where you find things out while the cost of changing something is low rather than after it’s been replicated across a hundred customer journeys. Where you find things out while the person in front of you is mildly inconvenienced rather than on social media explaining the specific and intimate discomfort of your decision.

The other thing — and this is the part of the crotch rivet story that tends to get left out — is that when Levi’s removed the rivet, they replaced it with something better. Bar tacks. More flexible, more durable, no heat conduction, no saddle scratching. The problem, once taken seriously, led to a solution that improved on the original.

This is the thing about campfire testing: it doesn’t just tell you what’s wrong. It tells you what the problem actually is, which turns out to be a more useful thing to know than whether the current solution passes inspection in the room.

The rivet worked. The bar tack works better. The difference is a trip to the campfire.

_{*The specific test worth running: give the thing to the most awkward, most edge-case, most likely-to-encounter-an-unintended-consequence person you know, and watch what happens. This person is usually easy to identify. They are the one who, when you describe your idea, says “but what about when…” and you say “nobody’s going to do that.” They are almost always right.}

_{**Bar tacks — the reinforced stitching that replaced the rivets — are, it should be noted, better at the actual job than the rivets were. They’re more flexible, they don’t conduct heat, they don’t scratch saddles, and they don’t wear through denim flaps. Removing the thing that wasn’t working occasionally leads, through the process of actually thinking about the problem, to a thing that works better. This is perhaps the most useful lesson of the whole story and the one most frequently omitted when it’s told.}

_{***The back pocket rivets went through a different version of the same process: in 1937 they were hidden under denim flaps after cowboys complained they were scratching their saddles. The hidden rivets eventually wore through the denim and caused the scratching anyway, at which point they were removed entirely. A solution to an unintended consequence, undone by a further unintended consequence of the solution. This is sometimes called iteration.}