You know the one. A long climb, six of us, everyone at their own pace. I get to the top and look back: three people. Where's the rest? So we stand there. Someone gets a phone out and types "where are you" into the group. Five minutes later: "coming". Which tells you nothing. Are they two hundred metres below us, or back at the bottom fixing a puncture?
That's the whole problem, really. I don't need to know where the others are. I need to know how far, and whether the gap is closing. That's what decides whether I wait or soft-pedal on.
We tried shared location in WhatsApp. It gives you a pin on a map. On a phone, while riding, in gloves, you genuinely cannot tell whether that pin is three hundred metres behind you or two kilometres. Everyone has to switch it on separately, and it turns itself off after eight hours.
Garmin has GroupTrack, which does exactly what I wanted: a number and an arrow to each rider. But everyone in the group has to have it. A Garmin head unit or watch, plus an account. In our group, one person does.
Sextant is a web page. One rider opens it on their phone, taps "Create a group" and drops the link into the chat we're already in. The others tap the link, type a first name, and ride. Nothing to install, nobody signs up, no code to copy out. It works the same on iPhone and Android, which in our group was where everything else fell apart.
And then everyone sees, for everyone else, the distance in metres and an arrow. "Jana 538 m", "Kuba 1.1 km". The numbers move while you ride, so you can see who's holding on and who's slipping before they disappear. Under a hundred metres it switches to a radar view for finding each other in a car park or in the trees. And whoever stayed home with a cold can watch from a laptop without sharing anything themselves.
Free. No account. Nothing to install.
It runs in a browser, so the screen has to stay on. The app asks for that itself, but the phone needs to be on the bars or in your hand, not locked in a jersey pocket. With no signal, positions stop updating. On the bike that doesn't bother me, the phone's there anyway; for a full day's hike with the phone in a rucksack I'd take something installed.
Battery: nothing runs in the background. You look, you see the numbers, you close it. Ten seconds.
This mattered to me when I was writing it. The group key is generated on the phone of whoever creates the group, and it lives in the link after the # sign. That part of an address is something a browser never sends to a server; that's just how they work. So the server only ever receives encrypted data it holds no key for, and passes it along. No history, no IP logging, the group disappears by itself after the ride. Just be careful who you send the link to. It is, in effect, the key.
It works the same way for a motorcycle convoy, where the phone's on a charger anyway.
More generally, on sharing location without installing anything, and how that differs from Find My or Life360.