---
title: Twelve minutes was the plan. Ten is nobody's business.
description: Walking the Berlin Marathon 5K at ten minutes per kilometre, and an app that remembers the loop but not who walked it. Privacy by design, seen on foot.
---

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# [Twelve minutes was the plan. Ten is nobody's business.](https://www.protagx.com/en/ddd/twelve-minutes-was-the-plan)

 Written by [Christian Schappeit](https://www.protagx.com/en/ddd/author/christian-schappeit) | Oct 15, 2026, 11:00:00 AM

**DATA DIVERS DIALOGS · ESSAY**

> *A couple flew halfway round the world to walk five kilometres the day before the Berlin Marathon. The app that helped them knows the shape of their loop, how long it took, and nothing else. That last part is the interesting one.*

By Christian Schappeit · Data Divers Dialogs · October 2026 · approx. 5 min read

Saturday, 26 September, Potsdamer Platz. The Generali 5K runs the last five kilometres of the Berlin Marathon course, through the Brandenburg Gate, one day before the real thing. Entry is 34.50 euros. There is a medal. And there is one rule that matters more than the others: you have one hour from the moment you cross the start mat.

That hour is why a couple from the US flew halfway round the world to stand on this corner. One of them runs the marathon tomorrow, after months of training. Neither of them sets best times anymore. They wanted to walk the 5K together, and before booking anything they needed one answer.

*Can you walk this in under sixty minutes?*

**THE ARITHMETIC**

## Twelve minutes a kilometre is not a training plan. It is permission.

In a strange city a map tells you very little. Streets are lines. A line does not say whether the stretch past the Tiergarten is pleasant or a six-lane road with a pavement attached.

So they opened encirkl.de, a Berlin walking app, and found that somebody had already done the work. The 5K route was in there as a challenge for the marathon weekend: a closed loop, walked by real people, with a duration attached.

The app makes a point of not caring how fast you are. No sport, no tempo, no kilometres, says the front page. That turned out to be exactly right. A fitness tracker would have told them their pace was disappointing. This one simply showed that people close the loop on foot.

The rest fitted on a beer mat. Sixty minutes, five kilometres: twelve minutes per kilometre. A brisk walk, not a sprint.

**THE ENTOURAGE**

## Every marathon runner travels with people who don't run

At the start they noticed they were not alone. Other couples, whole families, all built on the same pattern: one runner who had trained for months and wanted one last easy lap, and everyone else, who had come for the city.

More than 50,000 athletes were expected for the weekend. Every one of them brings company. Nobody designs anything for the company. It stands at kilometre 38 holding a sign, and then it goes looking for lunch.

Later that day the runners and their people turned up in the same places, the cafés worth sitting in, the streets worth walking. They knew where the good places were. They had an app.

That evening I went to my favourite restaurant. You treat yourself on marathon weekend. At the next tables: a woman from Bangkok travelling alone to run, the couple from the US, a small family. In Bangkok, she said, running has become a thing, and walking even more so. Consider the climate. Anyone who walks five kilometres there in the afternoon has earned the Brandenburg Gate. All of them had built a trip around a run. All of them had walked their peers' favourite loops. People waved across the room. See you next year.

**WHAT THE APP KEEPS**

## Four things, and none of them is you

Nobody in that restaurant had exchanged numbers or followed anybody. Which made me curious about what the system behind all this actually knows about them.

Less than I expected. The loop is validated on the phone, and the GPS trace stays there. Per loop the server keeps four things: the shape, the elevation, the duration and which challenge it belonged to. The shape is stored with a random start point, not the one where you actually set off. Loops are not linked to each other. No account is needed to start.

The random start point sounds like a detail. It is the whole design. A loop that begins and ends at the same front door is an address with extra steps.

We know this because it has already happened. In January 2018 an analyst looked at Strava's public heatmap, built from about three trillion GPS points, and noticed that soldiers jogging laps around remote compounds had drawn the outlines of military bases. The data was aggregated and anonymised. The jogging routes did not care.

> "A loop that begins and ends at the same front door is an address with extra steps."

encirkl's answer is to throw away the part that points home before it ever reaches a server. The same logic runs through the rest. When someone redeems a perk at a partner café, the café receives a yes or a no and a badge level. Not a route. Not a name. The website sets no cookies, and the platform is hosted in the EU.

**FROM THE CRM SIDE**

## A loyalty programme that refuses the email address

In every loyalty programme I have worked on, the first screen asks for an email address. Everything after that is built on it: the profile, the segment, the campaign, the consent record that legal wants to see when something goes wrong.

This one starts by declining the address. From a CRM point of view that sounds like heresy, until you notice what it keeps instead: proof that something happened, and nothing about who did it. In regulated industries we spend a great deal of money trying to separate those two things after the fact. Here they were never joined.

It leaves a fair question for anyone who sells customer data platforms. If a café gains a guest through a loop and never learns who she is, what exactly is the customer relationship? Possibly it belongs to the route, not to the person.

**MY OWN LOOP**

## Ten

I walked it too, that Saturday. I had done the same arithmetic as everyone else and planned for twelve minutes a kilometre, with a little reserve for the photo at the Gate.

It came out at ten. Fifty minutes for five kilometres, on foot, with no app telling me whether that was good.

Somewhere on a server in the EU there is now a loop of about that length, with a duration of about fifty minutes and a start point that is not where I started. The app does not know it was mine. You do now. That was my decision, not the app's, which is rather the point.

**Figures and sources.** Generali 5K: Saturday, 26 September 2026, start Potsdamer Platz, finish on Straße des 17. Juni after the Brandenburg Gate, time limit one hour from crossing the start mat, entry fee 34.50 euros (haid.app event summary; organiser page). "More than 50,000 athletes" for the marathon weekend is from Berlin local reporting on road closures. Strava: heatmap built from roughly 3 trillion GPS points from 2015 to September 2017, problem flagged by analyst Nathan Ruser in January 2018.

On encirkl's privacy claims: the four stored items, the random start point and the no-linking statement come from encirkl's own homepage. The privacy policy confirms the partner side (yes/no, no names, no location or movement history passed to partners), EU hosting and the cookieless website, but is worded more cautiously on the app: it says processing stays on the device "where technically possible" and refers to the CursusX platform policy for app details. Treat the homepage description as the vendor's account, not an audit. Disclosure: protagx designed the encirkl website. The walk, the restaurant and the pace are my own experience.

[encirkl.de](https://www.encirkl.de) · [encirkl privacy policy](https://www.encirkl.de/datenschutz) · [Generali 5K, organiser](https://www.bmw-berlin-marathon.com/en/registration/generali-5k) · [haid.app event summary](https://haid.app/en/events/generali-5k-mq93apiq) · [monrose.de on the marathon weekend](https://monrose.de/2026/09/16/berlin-marathon-2026-strassensperrungen-am-26-und-27-september-diese-strassen-und-bezirke-sind-von-sperrungen-betroffen/) · [Bitdefender on the Strava heatmap](https://www.bitdefender.com/blog/hotforsecurity/secret-military-bases-exposed-soldiers-fitness-trackers/)

[View full post](https://www.protagx.com/en/ddd/twelve-minutes-was-the-plan)

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