/n/ - Transportation » Thread #1349239

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113KiB, 883x883, sigma-sport-bc-23-16-sts-fahrradcomputer-2017-248785-c.jpg

Anonymous Thu 20 Jun 2019 08:17:49 No.1349239 View View Reply Original Report

Quoted By: >>1349258 >>1349621 >>1349776 >>1349991

>buy pic related for $130
>overcomplicated and German, so don't even know half of what it does until I get it
>manual says it has a power monitor where it estimates your power output from your speed and the hill grade and air density and you and your bike's weight/dimensions/etc.
>seems plausible, you ought to be able to get something reasonably in the ballpark with some basic physics formulas and estimates on parameters and so on...
>"A strong headwind or tailwind can lead to deviations between the calculated value and the actual power generated"
>realize it has no way to know the wind speed and direction so any number it gives will be massively inaccurate unless it's a completely still day

WHY EVEN SHIP THE PRODUCT WITH THIS FEATURE IF IT'S SO COMPLETELY BROKEN

(bretty gud otherwise)

Anonymous

Anonymous Thu 20 Jun 2019 08:26:32 No.1349240 Report

Quoted By: >>1349241 >>1349695

Just buy a power meter lmao they’re getting to be pretty cheap

Anonymous

Anonymous Thu 20 Jun 2019 08:29:37 No.1349241 Report

Quoted By:

>>1349240
I don't care enough to actually buy one but if this one had worked I might've used it. I didn't buy it for that anyway, I bought it because it seems to be the cheapest one out there that lets you have speed/distance/cadence all on the screen at the same time

Anonymous

Anonymous Thu 20 Jun 2019 09:52:48 No.1349249 Report

Quoted By: >>1349250 >>1349260

>WHY EVEN SHIP THE PRODUCT WITH THIS FEATURE IF IT'S SO COMPLETELY BROKEN

indoor training is a thing

Anonymous

View Same Google ImgOps iqdb SauceNAO nope.jpg, 70KiB, 1420x946

Anonymous Thu 20 Jun 2019 09:54:12 No.1349250 Report

Quoted By:

>>1349249
>training indoors

Anonymous

Anonymous Thu 20 Jun 2019 10:06:52 No.1349258 Report

Quoted By:

>>1349239
The power estimation feature is meant for climbs and it can do that with relatively good accuracy as long as it's not super windy. Though you can get the same feature with Strava so there's no point in paying extra for a head unit that does it.

Anonymous

Anonymous Thu 20 Jun 2019 10:14:14 No.1349260 Report

Quoted By: >>1349273

>>1349249
it's measuring power from your airspeed so won't work on a stationary bike, you'd just get whatever power it takes to move your bike at the speed of the air from your fan

Anonymous

Anonymous Thu 20 Jun 2019 11:12:13 No.1349273 Report

Quoted By: >>1349302

>>1349260
It's measuring speed from a magnet on the wheel. It doesn't have anything to measure airspeed with, besides, that would be retarded.

Anonymous

Anonymous Thu 20 Jun 2019 12:46:08 No.1349302 Report

Quoted By: >>1349780

>>1349273
>not installing an anemometer on your Cervelo

Anonymous

Anonymous Fri 21 Jun 2019 04:50:08 No.1349621 Report

Quoted By: >>1349623 >>1349629

>>1349239
why is it so expensive? what does it do that the $20 models dont?

Anonymous

Anonymous Fri 21 Jun 2019 04:56:48 No.1349623 Report

Quoted By: >>1349629

>>1349621
picture of a ghost in the bottom right

Anonymous

Anonymous Fri 21 Jun 2019 05:02:32 No.1349629 Report

Quoted By: >>1349632

>>1349621
>cadence sensor
>heart rate sensor
>altimeter
>sync shit to your phone
>lots of random stats

>>1349623
Also this. You can record rides and race your 'ghost'.

Anonymous

Anonymous Fri 21 Jun 2019 05:09:06 No.1349632 Report

Quoted By: >>1349634

>>1349629
sounds like it wont run for a year with a cr2032 like the simpler models do

Anonymous

Anonymous Fri 21 Jun 2019 05:13:47 No.1349634 Report

Quoted By: >>1350807

>>1349632
Batteries are cheap. Actually needs a 2032 in each sensor + a bigger one in the head.

Anonymous

Anonymous Fri 21 Jun 2019 08:15:15 No.1349695 Report

Quoted By:

>>1349240
unless you race theres no point in buying a power meter the numbers mean nothing unless you are training and test your regularly

Anonymous

Anonymous Fri 21 Jun 2019 13:40:02 No.1349776 Report

Quoted By: >>1349798 >>1349839

>>1349239
>buy pic related for $130
why though

Anything powermeasurment is bullcrap unless you have actual powermeters in the crank. You could have figured this before by using your head a little.

>speed
Use GPS. Don't use a tire sensor.

>heart rate
Use an actual chest strap or maybe a smartwatch (I don't know how accurate they are)

>power
Use a powersensor in the crankset

Anonymous

Anonymous Fri 21 Jun 2019 14:02:57 No.1349780 Report

Quoted By:

>>1349302
>his bike doesn't have a pitot tube
o i am laffin

Anonymous

Anonymous Fri 21 Jun 2019 14:47:31 No.1349798 Report

Quoted By: >>1349800

>>1349776
>why though
Because it's the cheapest thing I could find that lets me have speed+cadence+distance on the screen at the same time. Also having an altimeter is nice. Didn't even know about the power thing until I got it.

>Anything powermeasurment is bullcrap unless you have actual powermeters in the crank. You could have figured this before by using your head a little.
The accuracy would be usable if it knew the wind. The biggest terms in the power equation are gravity and air resistance, and the only hard-to-get numbers needed to evaluate them (besides wind) are the slope of the hill you're on and the drag coefficient. The altimeter handles the inclination and the drag coefficient can be ballparked by inputing some body dimensions and info about your posture.

https://en.wikipedia.org/wiki/Bicycle_performance#Power_required

For a tenth the price of a normal power meter it would be worth doing if not for the wind thing.

>Use GPS. Don't use a tire sensor.
If measuring distance by counting wheel rotations is good enough for car odometers, it's good enough for my bike. I actively _don't_ want GPS on my bike (or car), I am a human being capable of finding my own way around and not an animal that needs to be lead around on a leash tyvm.

>Use an actual chest strap or maybe a smartwatch (I don't know how accurate they are)
It comes with a chest strap. I don't use it because I don't care about that.

Anonymous

Anonymous Fri 21 Jun 2019 14:55:14 No.1349800 Report

Quoted By:

>>1349798
There is actually a powermeter that does what you describe using an actual wind meter (?), maybe slightly cheaper than a "real" power meter, kind of accurate but can't account for stuff like posture on the bike etc.

Really though single sided strain gauge based meters have become fairly affordable so there's not much reason for it these days.

Anonymous

Anonymous Fri 21 Jun 2019 17:10:22 No.1349839 Report

Quoted By: >>1350718 >>1351069

>>1349776
>Use GPS. Don't use a tire sensor.
GPS slow, use hall sensor in wheel motor.
>Use a powersensor in the crankset
Use amp meter and voltmeter. Crankset is bloat

Anonymous

Anonymous Fri 21 Jun 2019 23:06:57 No.1349991 Report

Quoted By:

>>1349239
Listen OP, anything that says it """estimates""" power when riding using alternative methods is utter and complete crap and you threw your money away. The only method of measuring the power your legs are generating is by directly measuring the torque generated, either at the pedals themselves, at the crankset, or at the rear hub. If you're trying to use something like this for actual training, then you're sabotaging yourself, you'd be better off just using heartrate instead, at least you're directly measuring something related to your own effort instead of secondary and tertiary datapoints.
All that being said unless you're actually training in a deliberate and structured way, measuring power is useless data. You have to do actual performance testing in a controlled and repeatable way to establish power zones used in training, otherwise any power measurement is just a number with no relation to anything significant. A recreational or commute rider does not need to know how many watts he's generating, the information is not useful to him, heartrate would be more useful.
Just ignore what it's telling you, turn that part of the display off if you can. Sigma makes decent cyclocomputers otherwise.

Heart rate monitor

View Same Google ImgOps iqdb SauceNAO 1559934930069.jpg, 413KiB, 1024x576

Heart rate monitor Sun 23 Jun 2019 09:14:09 No.1350714 Report

Quoted By: >>1350731

Anyone knows a reliable heart rate monitor?
Power meter would be the best, but too much money for such a small tool.

I started to get into cycling and I only have my unreliable GPS data from my phone, which gives out speed, altitude gain is already totally unreliable and deviates greatly when I cycle the same route again.

Anonymous

Anonymous Sun 23 Jun 2019 09:29:41 No.1350718 Report

Quoted By:

>>1349839
>Use amp meter and voltmeter.
From a dynamo?
That will only tell you the potential energy you're carrying at that speed, not the power you're putting in.

Anonymous

Anonymous Sun 23 Jun 2019 09:41:06 No.1350723 Report

Quoted By: >>1350731

Anything other than an Apple Watch 4?

I don't have an iPhone, which makes the watch useless.

Anonymous

Anonymous Sun 23 Jun 2019 09:53:16 No.1350731 Report

Quoted By: >>1350740

>>1350714
>>1350723
Any heart rate strap with ant+ and bluetooth should work, garmin wahoo etc

Anonymous

Anonymous Sun 23 Jun 2019 10:09:21 No.1350740 Report

Quoted By: >>1350751

>>1350731
But they seem to be unreliable over all, all of them have mixed reviews.

Anonymous

Anonymous Sun 23 Jun 2019 10:35:30 No.1350751 Report

Quoted By:

>>1350740
much more reliable than optical ones like smartwatches

anecdotal obviously but I've had a garmin one for 4 years now and never even needed to replace the battery

Anonymous

Anonymous Sun 23 Jun 2019 12:29:48 No.1350807 Report

Quoted By:

>>1349634
I don't care about swapping a battery every six months but I'm not reprogramming a clusterfuck of rhythmic button presses where if you get one press wrong in a 5 minute sequence you have to start over

Anonymous

Anonymous Sun 23 Jun 2019 21:33:10 No.1351069 Report

Quoted By:

>>1349839
>Use amp meter and voltmeter. Crankset is bloat
You clearly don't understand anything. Power is measured by measuring torque using sensors either in the crankset, pedals, or rear hub. Torque and rotation equal power, simple physics. Having a 2kW dynamo on your bike, which you then short thtrough a resistor (creating heat) to measure power is the shitty brute-force approach and is not necessary.

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