How does this cycle path feel to ride?
Maps show where cycle paths are, but not whether they are smooth, rattly, loud or calm. Velowind measures that with the phones of people who ride them, and turns the rides into a comfort map. It is a data science project that starts small and is meant to keep growing.
A comfort map, built from real rides
Whether a route is pleasant depends on things a normal map leaves out: cracked asphalt or gravel, concrete slabs with a bump every few metres, a path squeezed next to a busy road, or a quiet lane through the fields. OpenStreetMap has tags for surface and smoothness, but they are missing or out of date for many ways.
Velowind fills that gap from the bottom up. While you ride, the app records how much the bike shakes, how loud it is around you, and where you are. Many rides over the same stretch, on different bikes, at different times and in different weather, add up to a reliable picture of that stretch.
The first goal is a map of path quality by surface, noise, time of day and weather. The long-term goal is a route planner that can find you the smooth and quiet way, not only the short one.
Vibration
accelerometer ~100 Hz · gyroscopeShows the surface: smooth asphalt, slab joints, cobbles, gravel. The analysis corrects for speed, so riding faster doesn't count as a rougher path.
Sound levels
26 third-octave bands · 50 Hz–16 kHz · every 125 msShows traffic, wind and quiet. The phone keeps only loudness per frequency band, so no speech or audio is ever stored.
Position and height
GPS 1 Hz · barometer 10 HzPlaces each measurement on the map and tracks climbs, which matter for how hard a stretch is to ride.
Your ratings
surface · width · traffic · noiseA few one-tap answers about the spot you are on. They are the ground truth that the models learn from.
From raw sensor data to a map
Velowind started as a data science project and is built in the open. This is the path from a ride to the map, and where it stands today.
Collectrunning
The Android logger records all sensors and uploads finished rides over Wi-Fi to the project server.
Clean and alignrunning
Sensor clocks are checked against real time and start and end of every ride are cut for privacy.
Match to the street networknext
GPS tracks will be matched to OpenStreetMap ways.
Featuresfirst tests
Vibration per frequency band and noise per frequency band were tested on first test rides. Next come gradient, bike type and phone mount, so that data from a road bike and from a cargo bike can be compared.
Add contextnext
Weather (rain, temperature, wind) by time and place, plus time of day and day of week.
Modelnext
Classifiers for surface and roughness trained on rider ratings, checked against OpenStreetMap smoothness tags.
Mapnext
An interactive map of path quality, with filters for time of day, weekday and weather.
Where it can go next
Velowind Routes
A route planner that weighs comfort: smooth surface, little traffic noise, gentle climbs, and the wind of the day.
Less data from each phone
A small model on the phone that turns 100 readings per second into a few numbers per stretch. By a rough estimate that could cut the upload size about a hundredfold.
How hard is this stretch?
An effort score per stretch from gradient, rolling resistance of the surface and headwind, checked against how real riders slow down.
More riders, more places
The app accepts anyone who installs it. With more riders, the map can cover more of a city, and more weather, seasons and times of day.
Built so that rides can't point back to you
You don't make an account and you don't give a name. Nothing leaves your phone until you agree to the upload in the app.
What is uploaded
- Motion sensor data, the GPS track and sound levels in frequency bands
- Your ratings of spots on the ride
- The type of bike (for example "trekking"), the phone model and app version
- A random id for your app install, so you can delete your data later
What never leaves your phone
- Audio of any kind: the phone stores loudness per band, not sound
- The first and last 150–250 m of every ride, cut at a random radius so your home or work can't be found
- Your name, contact details, or the names you give your bikes
- The full track you can export as GPX for yourself
You stay in control. Automatic upload runs only on Wi-Fi and can be switched off. Settings → Delete my data on the server removes everything your phone has sent.
Get the app
The app isn't in the Play Store yet, so Android asks you once to allow the installation. It needs Android 10 or newer.
Download the APK
Open apk.velowind.de on your phone. It always gives you the newest version. Each release is also on GitHub, together with the source code.
Allow the installation
Open the downloaded file. Android asks whether your browser or file app may install apps: tap Settings, turn on Allow from this source, go back and tap Install. If Play Protect warns about an unknown app, choose Install anyway.
Set up your bikes
Open the app, pick the bikes you ride, and allow location, microphone and notifications. Each bike gets its own start button.
Let it run in the background
In Android settings, open the app, then Battery, and choose Unrestricted. Otherwise some phones stop the recording when the screen is off.
Agree to the upload
The app shows what it sends and asks once. After that, finished rides go to the project server whenever you are on Wi-Fi. You can upload your recordings always manually (Settings → Upload now)
Updates come by themselves: the app checks once a day and offers a new version with one tap. Your rides and settings stay.
Just ride the way you always do
Start
Tap the button of the bike you are on before you set off. A notification shows that the ride is recording.
Where to put the phone
A firm handlebar mount gives the clearest data. Rides with the phone in your trouser pocket, or carried on you some other way, help too.
Rate what you notice
When something stands out, like a rough patch, a narrow path or loud traffic, rate it in a few taps. But only when it is safe: if you stop, or with a brief tap on a mounted phone, as traffic law allows.
Stop
End the ride in the app. If you forget, it stops by itself after 10 minutes standing in one place, and leaves the standing time out.
Any ride counts
Your commute, the shopping trip, a weekend tour. Riding the same way often is useful too, because it shows how a path changes with weather and time of day.
Don't share the mic
Other apps that use the microphone at the same time, like calls or noise meters, block the sound measurement. The app warns you if that happens.
Good to know
Is there an iPhone version?
Not yet. Distributing iOS apps outside the App Store needs a paid developer account, so the project starts with Android.
How much battery and data does it use?
Recording keeps GPS and the sensors on, similar to a sports tracking app. A 30-minute ride is a few megabytes and is uploaded only on Wi-Fi, unless you choose "Upload now" on mobile data.
Can my rides be traced back to me?
Rides carry a random install id, never your name or phone number. Start and end are cut away before upload. Someone who already knows where you ride could still recognise a route, which is why the cut uses a different random radius for every ride.
How do I stop taking part?
Turn off automatic upload in Upload settings, or use "Delete my data on the server" there and uninstall the app. Rides on your phone are removed with the app.
Who can see the data?
Uploaded rides are stored on the project's own server and used for this research project. They are not sold or shared with advertisers.