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Thread: "Freeze Points" metric

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    vvill's Avatar
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    Cool "Freeze Points" metric

    Hi folks,

    You may have a noticed a new "Freeze Points" graph under the Individual (Various) leaderboards. This is a sort of experimental metric that's intended to capture the spirit of riding regularly in the cold, but not necessarily long distances.

    Each of your rides is scored based on both the starting temperature of the ride, and your ride distance. Your highest scoring ride of the day is added to your BAFS season total.

    However, there are diminishing returns: -
    1. You are awarded for riding more up to a "sweet spot" of around about 3-7 miles. You can ride longer of course, but you there isn't much reward.
    2. You are awarded more for rides that start at cold temperatures, especially below freezing temperatures. Between about 38-45F you can't score as many, but as you get to 32F and below, you get significantly higher scoring rides. Below about 25F the diminishing returns come back into play - as long as it's around freezing or less, you will add more to your score.


    There are no daily ride bonuses and therefore no "sleaze days" in this metric (...although there's no reason you couldn't go out at 12:01am each morning and ride 5 miles!) There may or may not be a pointless prize given away based on this. I haven't spent a lot of time on calibrating/tuning the scoring function so it may be subject to change. Feedback is welcome! Obviously you can "game" your score to some extent, but I think generally it does a decent job rewarding those who ride a non-trivial distance in cold weather on a regular basis which is what I feel BAFS is all about.


    Big thanks to hozn (as usual) for adding my code to the website! Temperatures are based on the same data used throughout the site (Weather Underground API).






    This shows how many Freeze Points you would get for a range of starting temps/mileages:

    The shape is not too dissimilar from the NWS windchill chart although my mileage scale is not linear and I'm not using exponentials. Above 45F you actually get a (small) negative score - I should probably change this to just be 0.

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    I was telling vvill we should consider making this the scoring system in future years. It doesn't hugely shake up the leaderboard, but I think it captures the spirit of the competition. (I also kinda like the idea of getting rid of sleaze rides -- or if we keep a daily reward, also make the points factor in temperature.)

    I would say adding precipitation could be interesting; however, we've seen this to be pretty unreliable in wunderground data. Plus riding "in the snow" is often a lot harder than riding "while it's snowing".

    Personally I love the penalty for > 45 too It really changes the competition.
    Last edited by hozn; 02-08-2016 at 02:55 PM.

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    Nooooooooooooooooooooooo!

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    Quote Originally Posted by hozn View Post
    Personally I love the penalty for > 45 too It really changes the competition.
    Haha, glad to hear it. I love it too, but figured most folks wouldn't want any rides to be negatively scored. Obviously we could take it even further and move it closer to 40F but 40F in windy rainy conditions would be suffering enough for some points.

    And on that note I agree that if we took into account wind, precipitation and even daylight vs nighttime as well it would be great, but unfortunately those are not as easily qualified as temperature, and the spirit of "Freezing Saddles" implies just freezing cold weather and riding a bike.



    I wouldn't push to make this the main scoring system, just a fun alternative. Maybe more for the hardcore riders, because we're not trying to encourage them to just ride a mile at some point every day, we're encouraging them to ride a few miles every day whatever the temperature may be (and especially on cold days, I guess). There's no reason we couldn't have multiple scoring systems/awards with the excellent framework / database that hozn/jrenaut have set up.
    Last edited by vvill; 02-08-2016 at 03:20 PM.

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    How fine is the resolution on the temperature data? There are days where the temperature reported on my rides doesn't match what the thermometer outside my window says. Same is true for other weather data, but that's outside the "freeze points" discussion.

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    Quote Originally Posted by dkel View Post
    How fine is the resolution on the temperature data? There are days where the temperature reported on my rides doesn't match what the thermometer outside my window says. Same is true for other weather data, but that's outside the "freeze points" discussion.
    This probably doesn't your question completely, but the weather data doesn't come from your Strava ride (which comes from your Garmin, or whatever). The Freezing Saddles site uses Weather Underground's data, but I'm not sure about the resolution.

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    Weather data will always be difficult to get right; not sure how you have the API setup, but I imagine that you query the hourly reported temperature for the same GIS-derived location as the ride-start? So if I start my ride at home in DC, you'll pass that lat/long combo along to wunderground, which will identify the closest monitoring station and then return the temp at ride start...

    One issue is that the weather station might not be reflective of my actual location (but its probably good enough for the purposes of this competition)

    Another issue is if I have a long ride that takes me to locations that end up being colder than my starting point, then I don't get to capture the benefit for my bafs points calculation.
    (ie, if I ride from DC - relatively warm due to heat-island effect - out to Sugarloaf, I might end up with a nice 5-10F drop in temperature. That would make a pretty big difference in the calculation - although it appears that the distance vs temp mechanism would negate the effect of me riding really far to a colder location.

    Perhaps introducing a POI into your Garmin/Strava recording for the midpoint of a long ride that would capture the location where it was colder, and have the API gather both locations and report wunderground readings for both...? (ie. it captures a 34F temp at my starting location, then it also gets a 27F temp at Sugarloaf and performs a calculation based on both readings).

    Clearly not something to implement this year, but worth consideration for future years.

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    Quote Originally Posted by Bilsko View Post
    Weather data will always be difficult to get right; not sure how you have the API setup, but I imagine that you query the hourly reported temperature for the same GIS-derived location as the ride-start? So if I start my ride at home in DC, you'll pass that lat/long combo along to wunderground, which will identify the closest monitoring station and then return the temp at ride start...

    One issue is that the weather station might not be reflective of my actual location (but its probably good enough for the purposes of this competition)

    Another issue is if I have a long ride that takes me to locations that end up being colder than my starting point, then I don't get to capture the benefit for my bafs points calculation.
    (ie, if I ride from DC - relatively warm due to heat-island effect - out to Sugarloaf, I might end up with a nice 5-10F drop in temperature. That would make a pretty big difference in the calculation - although it appears that the distance vs temp mechanism would negate the effect of me riding really far to a colder location.

    Perhaps introducing a POI into your Garmin/Strava recording for the midpoint of a long ride that would capture the location where it was colder, and have the API gather both locations and report wunderground readings for both...? (ie. it captures a 34F temp at my starting location, then it also gets a 27F temp at Sugarloaf and performs a calculation based on both readings).

    Clearly not something to implement this year, but worth consideration for future years.
    I think there is actually an "average temperature" per ride in the database that could be incorporated quite easily, but as a first run I didn't want too many variables or too complex a query. One of the benefits of diminishing returns on mileage is that the temperature probably won't change much during someone's first 5-8 miles of riding, which is about all that matters for this scoring anyway. Admittedly a 34F vs 27F ride would be a big score difference though.



    (hozn/jrenaut could tell you more about how the temperature data is obtained, I think.)
    Last edited by vvill; 02-08-2016 at 04:19 PM.

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    Quote Originally Posted by vvill View Post
    Above 45F you actually get a (small) negative score - I should probably change this to just be 0.
    I don't know. -3 points for 200 miles at 50 degrees. Sounds okay: we gotta rein in subby somehow.

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    One other wrinkle would be sort of like the 2nd derivative.
    The freeze points list still has a lot of the same names at the top.
    I noticed that I'm at 87 on the freeze points list, but 71 on the leaderboard. What does that mean? I think it means that I generally start my commutes after sunrise and hence the temp of my typical daily ride is a few degrees higher than others. Also, that I live in closer to the urban heat island than, say, sethpo (68 on freeze points list; 100 on the leaderboard).

    What might be interesting is to identify the riders who vary the farthest in their places on the two lists. If you are much higher on the freeze points list than the leaderboard, then you are a cold-weather badass. And vice versa.

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