Element Bolt accuracy

smac

I did a sportive at the weekend. ( White Rose Classic) The route was published at 86 miles / 6927 ft . My bolt recorded 86 miles and 9300 ft! I heard someone else say they had over 8000 ft so the published data was probably wrong. Anyone else noticed similar? Is there a problem with the unit?

wongataa

Never trust the elevation data recorded on any GPS head unit. There is nothing wrong with your device.

Devices without barometers use the GPS system for calculating the elevation data. The vertical component of GPS is less accurate the the horizontal positioning. This heavily affects the potential accuracy of the numbers. More expensive units such as the Bolt and equivalent Garmin units have a barometer for elevation measurement. This should be a lot more accurate. But the weather can heavily affect the elevation readings. If the air pressure drops the device will record an elevation increase even if the actual elevation of the ground is level for example. How well calibrated is the barometer? Electronic barometer output signal are affected by temperature. How well is the temperature compensation carried out on your device? Is there even any temperature compensation?

Because of these issues you ca't really know if the number on your device is accurate. Different examples of the same device will likely give different readings. Different devices will give different readings. Whose is correct?

Also, how do you know how accurate the number put out by the organiser is? Is it from proper survey data? Is it from whatever Strava/RwGPS says the elevation is? The elevation numbers from online route planners can be fully trusted either as it is affected by the accuracy of the elevation data they use and that has know issues.

In the end don't worry about it. It doesn't matter that much really. Whenever I get back from a ride of a circular route I am pleased if my Garmin reports the same number for elevation gained and lost - sometimes the numbers are far apart when in reality they are identical.

N0bodyOfTheGoat

It's not as wildy off as it used to be, but I still always correct elevation from my Lezyne Super GPS, which has a barometer. On the main ride summary page on Strava, you can click the blue elevation (if you are using a barometer GPS unit) and miles to get Strava to correct the figures.

Yesterday afternoon I clocked up ~4500 feet around East Meon according to the Lezyne, this was corrected by Strava to ~4700 feet. Two years ago, on early firmware for the unit, it wasn't uncommon to see a discrepancy of 500-1000 feet.