The Folds that work best aren't the ones we expected.

We seeded the beta with a thesis. Fold In is for neighbors. The picture in our heads was a block, six houses, a shared lawn mower, a borrowed ladder, the occasional folding table for a birthday party. We invited a few groups that looked like that. They're using it. They're fine.

The Folds that are flying are something else. They're four-to-six grown siblings, plus the occasional partner. They don't live near each other, often three cities apart. They almost never see each other in person. And they're moving more borrows per week than any neighbor Fold we have.

What sibling Folds borrow

The mix is different. Neighbor Folds borrow tools and gear, predictably, drills, ladders, pressure washers, the camping stove. Sibling Folds borrow stuff that travels in a suitcase or a parcel: a particular cookbook, a dress for a wedding, the good carry-on luggage, a thermometer, kids' books that one sibling's kid has outgrown and another's hasn't yet, a sewing machine that ships back and forth twice a year.

The interesting part: a sibling Fold is comfortable shipping things. They're already mailing each other birthday gifts. They've already paid for postage to send a parka home that someone left at Thanksgiving. The friction we worried about for distance-based borrowing, mostly, doesn't exist. They've solved it socially long before they met our app.

Two sisters living three cities apart move more between them in a year than most neighbors move across a fence.

Why we didn't see this coming

Three reasons, in order of how much they sting:

• We're a team of three with no kids. The "kids' books / kids' clothes / kids' gear" flow that sibling Folds run on is not a flow that lives in our heads. We had to be told about it.
• We undervalued duration. Most of our design work assumed a borrow lasted a weekend. Sibling-Fold borrows last months. The "Borrows" timeline view we built assumed dense, short loops, it gets sparse and weird at month-long durations, and we're rebuilding it.
• The "due back" model is wrong for siblings. Sibling Folds barely use due dates. The relationship is the contract. "I'll send it back when you ask for it" is the actual return policy. We had to add "no fixed return date" as a first-class option, and it's now the default in a third of sibling Folds.

What we changed for them

A few things, none of them dramatic, all of them quietly informed by sibling Folds:

• "Send by mail" as a handoff option. The four-digit code still works, but the borrower types it in once the package arrives, not at a doorstep. Tracking number optional.
• The "what changed" strip. Sibling Folds don't open the app daily. When they do come back after a month, they need a quick scan of "here's what's new in the Fold." We built it for them. Neighbor Folds use it too, but they didn't ask for it.
• Care notes that travel. A care note matters more when the borrower is unboxing the item alone, in a different city, with no chance to ask a quick question. We made care notes mandatory for any item flagged "ships."

What this taught us about the product

The thesis was right in shape and wrong in particulars. Fold In is for small, high-trust groups. We assumed proximity was the proxy for trust. It isn't, exactly. History is the proxy. Siblings have decades of it. Neighbors have, on a good block, a few years. A grown-sibling Fold has more trust than a freshly-formed block Fold, even though one is six hundred miles wide and the other is six houses long.

We're not pivoting away from neighbors. Those Folds work. But the marketing copy and the onboarding flow have shifted to lead with "the people you trust most," and to stop assuming those people live on your street.

· with care,
Sam