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· Premium Member
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Discussion Starter · #1 ·
Up until recently, I didn't have any sort of cyclocomputer or HRM.

I just bought a Ciclosport HAC4, and I'm going over the data from it. It's actually kind of fun. Apart from just speed and heart rate, it also contains an altimeter.

I'm pretty sure the "power" data it computes is garbage (too many assumptions), but I'm wondering if the altimeter is reasonably accurate.

After calibrating it, it basically agrees with what Google earth says the altitudes are of a few given locations. I also looked at the gradient it claimed a road was that the highway dept. had put a grade sign on; it was right.

If so, then I think I can use Analyticcyling.com to come up with some reasonable guesses as to what kind of power I'm putting down, which would be pretty cool.

What do you think?
 

· Shirtcocker
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Argentius said:
Up until recently, I didn't have any sort of cyclocomputer or HRM.

I just bought a Ciclosport HAC4, and I'm going over the data from it. It's actually kind of fun. Apart from just speed and heart rate, it also contains an altimeter.

I'm pretty sure the "power" data it computes is garbage (too many assumptions), but I'm wondering if the altimeter is reasonably accurate.

After calibrating it, it basically agrees with what Google earth says the altitudes are of a few given locations. I also looked at the gradient it claimed a road was that the highway dept. had put a grade sign on; it was right.

If so, then I think I can use Analyticcyling.com to come up with some reasonable guesses as to what kind of power I'm putting down, which would be pretty cool.

What do you think?
Not sure about the HAC, but my Polar 720i is nototriously inaccurate. It depends on barometric pressure and that can result in readings that are way off around here. It does tend to give you an accurate indication of vertical feet climbed/grade if you don't mess with it though.
 

· Adorable Furry Hombre
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32,357 Posts
Argentius said:
Up until recently, I didn't have any sort of cyclocomputer or HRM.

I just bought a Ciclosport HAC4, and I'm going over the data from it. It's actually kind of fun. Apart from just speed and heart rate, it also contains an altimeter.

I'm pretty sure the "power" data it computes is garbage (too many assumptions), but I'm wondering if the altimeter is reasonably accurate.

After calibrating it, it basically agrees with what Google earth says the altitudes are of a few given locations. I also looked at the gradient it claimed a road was that the highway dept. had put a grade sign on; it was right.

If so, then I think I can use Analyticcyling.com to come up with some reasonable guesses as to what kind of power I'm putting down, which would be pretty cool.

What do you think?
If you calibrate it before you start, HAC4s barometric altimeter is more accurate than GPS (unless you have some **waaaaay** nasty storm systems move in/out of your area).

The power estimates HAC4 spits out don't take into account air resistance really -so if you're going up nasty grades (or not-so nasty ones slow enough to make air-resistance negligible) it gives a decent figure I spose

Quoth the HAC4 Manual:

HAC4 Manual said:
The displayed power output measurements are approximate. The measurement are made in consideration of average friction, good road conditions, and the set weight. The output can be measured more accurately when ascending (accuracy = or -20 W, if the wind is strong then the measurements may vary more)....see pg 45
It's a neat toy though...I have yet to find a software which will let me interface myHAC4 w/ OSX though (grrrrr):mad:
 

· It's all ball bearings
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maybe reliably accurate to within a couple hundred ft

nahh, I wouldn't put too much too much confidence in the numbers it gives you. I'm sure it works fine as far as altimeters go but for the purposes you are thinking of using it for, I think you need to think of it more as "nice to know" information rather than reliable scientific data for using in modeling calculations. There are already plenty of sources of error in those power models on analyticcycling, adding another biggie source of error with the altimeter wont help the matter. Just figure out your position and use large scale (1:24,000 or better) topo map instead.

I'm sure you already know that you need to calibrate the altimeter as frequently as possible as atmospheric pressure changes. Two ways of doing this are to enter the elevation into the instrument at a location where the elevation is known (next to ponds and lakes that have elevations clearly marked to the nearest foot on maps are good places), and the less accurate way is to figure out what the pressure is in your exact location (only really works if you near an airport or weather station that reports updated altimeter settings).

I would also be hesitant to use that altimeter to plot elevation profiles for the same reasons as mentioned above, if you expect to plot them with any accuracy.
 

· Off the back.
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Bocephus Jones II said:
Not sure about the HAC, but my Polar 720i is nototriously inaccurate. It depends on barometric pressure and that can result in readings that are way off around here. It does tend to give you an accurate indication of vertical feet climbed/grade if you don't mess with it though.
This is pretty much my experience as well. I never use to Polar for an estimation of what my current altitude is, but I do use it for estimating climbing during a ride.

I never calibrate mine, just turn it on and go then dump the data.
 

· Premium Member
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Discussion Starter · #7 ·
I'm really not interested in my absolute altitude, but it would be cool to be able to use it to figure out things like how far I've climbed, the grade of the road, and that sort of thing.

1201, I had the same frustrations -- that's why I never bought one before -- but my ladyfriend has a PC, so I can make the poorly-translated software work.
 

· It's all ball bearings
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Argentius said:
I'm really not interested in my absolute altitude, but it would be cool to be able to use it to figure out things like how far I've climbed, the grade of the road, and that sort of thing.
Well for figuring out total feet climbed in a ride and so on, it'll probably give you a reasonable estimate, assuming the pressure remains constant over the duration of your ride.
 

· Adorable Furry Hombre
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Argentius said:
I'm really not interested in my absolute altitude, but it would be cool to be able to use it to figure out things like how far I've climbed, the grade of the road, and that sort of thing.

1201, I had the same frustrations -- that's why I never bought one before -- but my ladyfriend has a PC, so I can make the poorly-translated software work.
FWIW-in upstate NY & Nebraska-winter/summer weather in both, my HAC4s data is consistent with GPS data as well as topo data I've looked up [no flame intent, just IMOE]. As far as pressure changing in the house-that's not too surprising with HVAC as well as air flow issues in a closed building.

The software is actually fairly easy to use Argentius, it's the included documentation /manuals that've been translated from Esperanto->Cantonese->Swahili->...->Klingon->English (NTTAWWT) that sucks methinks. Only regret from switching to OSX on my part (grrrrr):mad:....
 
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