Strava Accuracy on Samsung Phone

wymthg

Wondered if anybody else had come across an issue with Strava on Phones, i was ruiding with a friend and I have a Garmin 500 and he uses his Samsung Galaxy on the handlebars in a case.

He stated we were doing 17mph and on my Garmin (with speed/cadance sensors), I had 14.5mph.

Is it normal for there to be such a big gap between the app and a GPS device like a Garmin?

thescouselander

No, that's not normal but there could have been some momentary inaccuracy if the phone had not locked on to enough satellites and was still refining your position. Did you check again later on?

wymthg

i would say the phone is consitently quicker that the Garmin, during a number of rides.

sungod

many consumer gps devices can have big errors in short term term speed calculation, unlike more sophisticated gps units that can use the doppler effect (which gives much better speed accuracy), they instead rely on a 2d 'join the dots' calculation between position estimates, typically with a bit of filtering to reduce jitter

errors arise because the estimated positions can be several metres out in any direction, also, if the true path is on a curve and/or slope the algorithm will underestimate the distance travelled if you are moving fast

variations in sample rate and algorithms between different devices may result in them giving different speed/distance information for the same course

craigr

Possibly not set up the speed/cadence sensor correctly? I too had problems with mine. I removed the sensor on the wheel so that cadence is recorded only. Maybe remove the wheel sensor and therefore use GPS signal for speed/distance and see if any better.

ednino

Garmin recently did an update to increase accuracy of the speed. Since the update mine does fluctuate as much

lotus49

Did the phone and the Garmin give reasonably similar distances covered for the ride? If they do, you can calculate the average speed yourself if you know the timing. If not, just try again but use a watch to measure the time you are out.

steve6690

Is he using the original Galaxy S, or is it an S2 or S3 ?. The gps on the original Galaxy is shockingly bad. I have a Galaxy S3 and have been very pleased with the gps accuracy. I ride a regular 12.25 mile loop and a 32 mile course. Using Endomondo and Strava the total distance measured by the phone is never more than 0.03 miles out. The S3 uses the Navstar and the Glonass satellites and it's very accurate.
Last week I hooked up an ant+ speed/cadence sensor and recorded the same ride using the ipbike app. My 12.25 mile course was measured at 12.19 miles on the speed sensor. I'm going to re-measure the rear wheel circumference. I set it at 211 cm but I wasn't sat on the bike at the time and I suppose my body weight might reduce the circumference marginally. It would only need to be out by 1 cm to explain the difference between 12.25 and 12.19.
I've found the gps speed on Endomondo to be pretty stable out on the open road, as is the output from the bike speed sensor, but they never seem to match.
My gut instinct is that the ant+ sensors should give a more reliable instantaneous speed reading.

ShilanAzem1136

so nice the phones is covering by this one.. i love this kind of perect things... accuracy

Samsung Gear Price in Dubai

markhewitt1978

wymthg wrote:

Wondered if anybody else had come across an issue with Strava on Phones, i was ruiding with a friend and I have a Garmin 500 and he uses his Samsung Galaxy on the handlebars in a case.

He stated we were doing 17mph and on my Garmin (with speed/cadance sensors), I had 14.5mph.

Is it normal for there to be such a big gap between the app and a GPS device like a Garmin?

GPS isn't perfectly accurate - on any device. The only way to properly determine speed at that moment is through a proper speed sensor on the wheel.

Measuring over distance the errors will even out so the GPS will be accurate for distance but second by second, which is needed for speed, it won't be.

wongataa

wymthg wrote:

Wondered if anybody else had come across an issue with Strava on Phones, i was ruiding with a friend and I have a Garmin 500 and he uses his Samsung Galaxy on the handlebars in a case.

He stated we were doing 17mph and on my Garmin (with speed/cadance sensors), I had 14.5mph.

Is it normal for there to be such a big gap between the app and a GPS device like a Garmin?

I would be checking the accuracy of the wheel size entered in the Garmin which is used for speed when using a speed sensor.

markhewitt1978

Garmin's are supposed to self calibrate the wheel size, by using data from the GPS over a period of time it can work out what wheel size you're using.

sloppyschleckonds

You are aware this thread is 2 years old?