National Bike Challenge 2014

[cvcalhoun]

Alas, the Garmin (Edge 500) doesn’t seem to have an “every second” option, unless I get a power meter. And I’m not willing to do that just to see whether it would fix the minor differences.

@hozn 88395 wrote:

Do you use “smart” recording on the Garmin or “every second”? Try the latter, if you aren’t and see if that improves things. I am guessing Garmin and Strava just have different smoothing algorithms to connect the dots recorded by the device. I typically found Strava to show *lower* numbers than the Garmin, though it seems like lately they line up pretty close. Strava is constantly tweaking their calculations and they likely do different things for different models of cycling computers.

[hozn]

@cvcalhoun 88396 wrote:

Alas, the Garmin (Edge 500) doesn’t seem to have an “every second” option, unless I get a power meter. And I’m not willing to do that just to see whether it would fix the minor differences.

Oh, it should. My 305 had that option and my 510 does (and I feel positive that my friends with edge 500 have discussed this). It should be under the “Data Recording” menu option.

(Yes, looks like it does: https://www.google.com/url?sa=t&source=web&rct=j&ei=3aWdU-aRMtezyASKzoKYAg&url=http://static.garmincdn.com/pumac/Edge_500_OM_EN.pdf&cd=5&ved=0CDUQFjAE&usg=AFQjCNEy2pwjmOAFzmcjS7wFNL8MJesBTA&sig2=KpQCo6KQLT9QLdo2mpTVfQ)

[consularrider]

@Rod Smith 88338 wrote:

… OK, I’m offering one free roll of toilet paper for every ride of 200+ miles by any teammate … Haha. :rolleyes:

Ok, qualified yesterday, to I get my choice of brands/type? Charmin with aloe please.

[PotomacCyclist]

@cvcalhoun 88385 wrote:

What’s bizarre is that if I upload miles to Garmin, and upload the same miles (from the same Garmin) to Strava, it always shows more miles on Strava. I’m not sure how the same file can be parsed so as to result in two different mileage counts, but it’s happened many times. This does not give me great confidence that either service is accurate down to 0.3 to 0.5 miles.

I think the data should be relatively accurate. I guess I had been using an estimate for a general ride from Arlington to downtown DC but I don’t remember the exact location of the end point from the previous rides. I’m riding a little farther north than before, which would account for the difference in mileage. In the past, I used to track the mileage frequently and the Garmin would always read the same distance, within a few hundredths of a mile.

[cvcalhoun]

Ah, okay. I’d found another forum that said it didn’t. Not sure whether they were wrong, or whether it changed. Anyway, I found the option and reset it. We’ll see whether that makes a difference.

@hozn 88399 wrote:

Oh, it should. My 305 had that option and my 510 does (and I feel positive that my friends with edge 500 have discussed this). It should be under the “Data Recording” menu option.

(Yes, looks like it does: https://www.google.com/url?sa=t&source=web&rct=j&ei=3aWdU-aRMtezyASKzoKYAg&url=http://static.garmincdn.com/pumac/Edge_500_OM_EN.pdf&cd=5&ved=0CDUQFjAE&usg=AFQjCNEy2pwjmOAFzmcjS7wFNL8MJesBTA&sig2=KpQCo6KQLT9QLdo2mpTVfQ)

[PotomacCyclist]

I used to have the 1-second setting enabled on my 305. But I learned that the setting causes a weird glitch. It would only record the first 2 or 3 hours of any workout (bike or run) with that setting. When I would load the data to SportTracks on my computer later on, everything after the 2 or 3-hr. mark would be missing. When I switched to Smart Recording, then all of my long workouts would appear complete.

I just checked the Settings menu on my 305. It says that for 1-second recording, the time limit of a workout is 3.5 hrs. After that, no data is recorded for the ride or run. For longer workouts, you have to use Smart Recording.

Unless you are making a lot of very tight turns, Smart Recording shouldn’t affect accuracy too much. The numbers won’t be precise, but I think the margin of error is relatively small.

[cvcalhoun]

Yeah, probably not worth fixing the small differences between Strava and Garmin at the cost of having parts of longer rides missing.

@PotomacCyclist 88417 wrote:

I used to have the 1-second setting enabled on my 305. But I learned that the setting causes a weird glitch. It would only record the first 2 or 3 hours of any workout (bike or run) with that setting. When I would load the data to SportTracks on my computer later on, everything after the 2 or 3-hr. mark would be missing. When I switched to Smart Recording, the all of my long workouts would appear complete.

I just checked the Settings menu on my 305. It says that for 1-second recording, the time limit of a workout is 3.5 hrs. After that, no data is recorded for the ride or run. For longer workouts, you have to use Smart Recording.

Unless you are making a lot of very tight turns, Smart Recording shouldn’t affect accuracy too much. The numbers won’t be precise, but I think the margin of error is relatively small.

[hozn]

@PotomacCyclist 88417 wrote:

I just checked the Settings menu on my 305. It says that for 1-second recording, the time limit of a workout is 3.5 hrs. After that, no data is recorded for the ride or run. For longer workouts, you have to use Smart Recording.

Yes, it uses more space. This should not be much concern for the 500, though. I typically just leave mine on smart, since I don’t care, and indeed the differences are small.

[vvill]

Smart recording uses less battery but records less often than 1 sec so your data will be slightly less accurate. Speed/distance shouldn’t be too different though if you are training based on recording your HR or power data you will want 1 second data, and I’d assume elevation data is more accurate with 1 second recording too.

The 500 is fine with long rides on 1 second recording.

[dasgeh]

Which reminds me, I think I’ve convinced Mr. dasgeh (every day around arlington, races and longer training rides 1/2x per week) to join. Should be able to sign him up tonight.

[PotomacCyclist]

I may have another recruit for the Washington Area All-Stars team, even though I’m not on the team myself.

[cvcalhoun]

We’d love another recruit! And if you’re not on a team, you’d be welcome to join us as well.

@PotomacCyclist 88488 wrote:

I may have another recruit for the Washington Area All-Stars team, even though I’m not on the team myself.

[cvcalhoun]

So I tried 1-second recording on the Garmin 500 today. The good news: It managed recording and uploading my 3+ hour ride with no apparent problems. The bad news: It didn’t correct the minor discrepancies between how Garmin and Strava calculate my ride, even though they are both uploading from the same device. Garmin says I covered 25.83 miles in 3:19:06, burning 939 calories. Strava says I covered 26.3 miles in 3:20:49, burning 1,334 calories. They agree that my elevation gain was 1,572 feet, my average heart rate was 115 bpm, and my maximum heart rate was 143 bpm.

@vvill 88427 wrote:

Smart recording uses less battery but records less often than 1 sec so your data will be slightly less accurate. Speed/distance shouldn’t be too different though if you are training based on recording your HR or power data you will want 1 second data, and I’d assume elevation data is more accurate with 1 second recording too.

The 500 is fine with long rides on 1 second recording.

[Rod Smith]

@consularrider 88401 wrote:

Ok, qualified yesterday, to I get my choice of brands/type? Charmin with aloe please.

After riding 200 I’d want aloe too, but Scott Naturals is the official sponsor of the NBC.

[vvill]

@cvcalhoun 88504 wrote:

The bad news: It didn’t correct the minor discrepancies between how Garmin and Strava calculate my ride, even though they are both uploading from the same device. Garmin says I covered 25.83 miles in 3:19:06, burning 939 calories. Strava says I covered 26.3 miles in 3:20:49, burning 1,334 calories. They agree that my elevation gain was 1,572 feet, my average heart rate was 115 bpm, and my maximum heart rate was 143 bpm.

As hozn mentioned, every website calculates distance/time slightly differently. Your GPS unit just records your coordinates at a set interval so it’s up to software to turn that into a track, distance and ride time. My guess would be that there is some smoothing applied to the coordinates, as well as movement that is ignored if it’s too small – since the GPS track is not that accurate. I have done many rides with two Garmins and I get up to 3 seconds difference on segment times on Strava from the same ride. That gives you an idea of GPS track accuracy for distance/timing.

The 1-second recording will give you better granularity for your data but I didn’t mean to imply you would get the same distance from different algorithms on different websites. (Btw, if you want the most accurate speed/mileage, a wheel magnet with a speed/cadence sensor GSC-10 is the best option – although again this is still subject to how your data is interpreted by the website.)

Calories burned are even more subject to calculation, and a ballpark estimate at best (as is elevation actually, because it’s based on barometric pressure readings and not temperature corrected). A calibrated power meter will give you a more accurate estimate of calories burned than any calculation based on speed/time/weight.

HR data is just straight data, so there isn’t much that can differ there.

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