snowEdge for iPhone and iPod Touch

  1. Why you need it
  2. How does it work
  3. How to use the app
  4. Application screens
  5. Battery saving tips
  6. TAI scale
  7. Contact us

Why you need it

If you are one of those snow sports enthusiasts who would like to attach a number to their achievement on the slopes, track their progress, compare to friends, you will find this application interesting.

How does it work

The basic question we attempt to answer here is what constitutes good skiing/riding. Obviously, the answer is not universal and is a matter of personal preference. Common answers:

These are the aspects we attempt to capture and quantify in the first version of the SnowEdge app. We do not have any idea how to measure the excitement of fresh powder snow and rely on your memories for this.

We strongly advise against trying to go with supersonic speed outside of a closed race course. Our personal preference (at least outside of trees and powder) lies with making nice dynamic turns. We designed a measure called Turn Acceleration Index (TAI) to track one’s progress in recreational skiing/riding. This measure is based on the lateral acceleration during the turn. Adding this acceleration to the gravity, we get full acceleration (g-force). Each TAI number is calculated taking into account your motion pattern in the last five seconds, which means two to four turns. In future we may add a long-term measure of activity.

How to use the app

Simply start the app and put the iPhone or iPod in you pocket. The screen will stay on, as necessary for continuous usage of accelerometer. Please do NOT lock the device pressing the button on top - this will disable accelerometer. This is it. Your runs will be automatically detected and saved in the memory. You can check the current statistics any time on the home screen without unlocking it. However, doing this simultaneously with inverted aerials is not recommended. The best time to analyze details of the last few runs is while you sit on a slow chair lift (if it's not too cold) or in front of a fireplace with a cup of tea a bit later. If you receive a message or a phone call, we recommend to restart SnowEdge app afterwards.

Application screens

Recording screen.
Application is monitoring your ski/ride activity. You can see the data from your last run and the best values for today.

Last Day screen.
This is the first screen you see after sliding the unlock slider. It gives you access to all recorded runs of your last day on the mountain. If your are still on the mountain, it will be today's day. In order to get back into recording mode, press "Record" slector on the bottom of the screen.

Best runs screen.
You can find the run with the fastest speed or highest TAI (Turn acceleration Index).

Here you can turn GPS tracking off. There is also an option to swith it off automatically when the battery level gets below 35% (recommended).

Run details.
You get to this screen tapping an individual run in other screens. You can select to see TAI, g-force and speed (if available) depending on time. You can zoom and pan the graph along the time axis to see individual turns on the g-force curve. G-force is close to 1 when you are not moving. Ironically, it's the same then you riding at 50 mph in a straight line, when the slope is not too bumpy. G-force is below one when you are flying free or just un-weighting your skis to change the edge. Its above 1 when you make a turn like this. In fact, it's above 2 in this turn, which means that lateral acceleration is close to 2g. Now it's time to hit the slopes, carve the best 4 turns you can make and see your g-force and TAI. We are thinking about grading ones skiing/riding levels based on TAI and need more statistics for that. We would appreciate your feedback with the self-estimated ability levels and the best TAI scores you get.

Battery saving tips

As mentioned above, the application must be active and the screen must stay on in order to record the motion. However, in our experience, using GPS is the biggest power drainer. Another important factor reducing battery capacity is cold. Acting together, these guys will deplete a full battery in a couple of hours. We like to use the app throughout the day, so we learned a few tricks. Some of these may be useful even without our app.

  • Keep the device in a warm inside pocket. Put a paper towel in the same pocket next to it. This may also help to keep it dry.
  • Reduce screen brightness
  • Switch off GPS if you are not too interested in the speed tracking. You may also want set your speed record early in the morning, when the slopes are mostly empty and switch GPS off after that.
  • Turn off WiFi and 3G

Using the tricks listed above helps to keep my iPhone 3G alive for a full day of skiing, 8am to 4pm. Buying a case with battery power should work nicely as well - I will try this next week.

TAI scale

Here is the scale from and our estimates of TAI.
We are not sure how the app will work for the level 1-3 skiers. Please let us know!

Level One: "Never-Ever"
Level One skiers are first time skiers who have never skied before.

Level Two
Level Two skiers are cautious novices who are able to do a snow plow (wedge) turn both ways and are able to stop, but linking turns smoothly may be difficult. Level Two skiers may have skied once or twice before.

Level Three
Level Three skiers are confident novices who are able to stop and make round snow plow turns on easy beginner trails.

Level Four, estimated TAI = 20
Level Four skiers are cautious intermediate skiers who can link turns but still moderate speed. Level Four skiers ski in a small wedge and their skis may even be parallel at the end of the turn on green or easy blue trails. Level Four is a transition level in which skiers will begin to ski more blue intermediate runs.

Level Five, estimated TAI = 30
Level Five skiers are intermediates who are confident on easy blue runs and ski mostly parallel but may at times use the wedge to begin a turn or to stop. Level Five skiers may be cautious on intermediate trails that are slightly steep or icy.

Level Six, estimated TAI = 50
Level Six skiers confidently make parallel turns on blue runs but do not ski many advanced trails. Level Six skiers use their poles to time turns. A Level Six skier is interested in learning to ski better on more challenging terrain.

Level Seven, estimated TAI = 70
Level Seven skiers ski controlled parallel turns and can ski very well on blue trails. Level Seven skiers can control their speed and rhythm on black diamond trails, but they are looking to ski on challenging trails with better style. Level Seven skiers can adjust the size and length of their turns and are learning to ski on a variety of different types of snow and terrain.

Level Eight, estimated TAI = 100
Level Eight skiers ski with good technique on all terrain and snow conditions. Level Eight skiers can ski moguls and are able to ski black diamond trails with confidence using carved turns.

Level Nine, estimated TAI > 150
Level Nine skiers enjoy the challenge of difficult ski trails and ski moguls, steeps, and other black diamond terrain.

There is a lot of room above TAI of 150. If you can make 300, the local race league is waiting for you. We really want to hear from someone who will break the 1000.

Contact us

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