Inconsistent Wahoo Elemnt Bolt Elevation Stats

New Topic
This topic has been archived, and won't accept reply postings.
 Cusco 15 Apr 2023

Has anyone experienced inconsistent elevation stats with a Wahoo Elemnt Bolt?

I’ve done the same route across Dartmoor four times (three times last year and then today). The first time the Bolt said the total elevation was 6,600ft, the next two times it said it was 6,400ft and today it said 7,000ft. It’s the exactly the same 63 mile route with the same hills. 

As far as I know, Dartmoor hasn’t risen since last year. 

Does it partly calculate by reference to barometric pressure or some such rather than actual height data via GPS?

 Marek 16 Apr 2023
In reply to Cusco:

GPS height data isn't particularly accurate and also 'total height gain' in the unit tends to accumulate errors due to noise. How much is dependant on whatever smoothing algorithm is used. I believe if you import the GPX file into a computer application (Strava?) it updates the profile using much more accurate terrain elevation data. Worth trying if you haven't done so already.

 ianstevens 16 Apr 2023
In reply to Cusco:

> Has anyone experienced inconsistent elevation stats with a Wahoo Elemnt Bolt?

> I’ve done the same route across Dartmoor four times (three times last year and then today). The first time the Bolt said the total elevation was 6,600ft, the next two times it said it was 6,400ft and today it said 7,000ft. It’s the exactly the same 63 mile route with the same hills. 

> As far as I know, Dartmoor hasn’t risen since last year. 

> Does it partly calculate by reference to barometric pressure or some such rather than actual height data via GPS?

It uses pressure, which is generally more precise/accurate that GNSS data for elevation. So wind, changing weather, blowing on the sensor etc will add noise which will accumulate, +- 150m isn't uncommon over a 100km ride and is pretty typical in my experience. I'm not familiar with Wahoo, but if you're a Strava or Garmin user you can force a correction using topographic data.

Post edited at 10:25
 Dave Cundy 16 Apr 2023
In reply to Cusco:

Even topographic data will have significant errors in it.  I use LocusMaps and their elevation comes from the 1990s Space Shuttle Radar Topography Mission.  However, i regularly multiply the height gain by about 0.7 depending on the terrain.  Noise in the data is a significant problem, especially on hilly terrain.

I would guess that 5% is a reasonable margin of uncertainty.  The SSRTM  data comes in 15m and 30m resolution datasets but both have significant errors on steep hillsides, cliffs and gorges. 

 Marek 16 Apr 2023
In reply to Dave Cundy:

I though SSRTM has accuracy issues (= apparent noise source) at tile boundaries rather than on steep terrain? I seem to remember you have to make sure you use the right corrected data sets if that's an issues for you. For random noise the problem should be more on flat ground rather than steep terrain where the slope > noise and therefore noise doesn't much impact accumulated climb stats? It's been a while since I used it though (in QGIS) so memory may be letting me down. If you want more accuracy/precision, there's always the LiDAR data sets.

 Jon Greengrass 17 Apr 2023
In reply to Cusco:

Yes the Element Bolt has a barometer. 

https://support.wahoofitness.com/hc/en-us/articles/115000441324-Why-am-I-Se...

I've seen some much wacky errors, a ride in Aberdeenshire last August where the temperature went down to -27C according to my BOLT. Turned it off and on again and it was back to recording the real temperature.

 LastBoyScout 17 Apr 2023
In reply to Marek:

> GPS height data isn't particularly accurate and also 'total height gain' in the unit tends to accumulate errors due to noise <snip>

Yup - I've had a height gain and loss of about 400m (iirc) on a flat running track! Whatever the error was, it seemed to correlate with the max +/- accuracy of the device (Timex Ironman) over the distance I ran that evening.

 Yanis Nayu 17 Apr 2023
In reply to Cusco:

My Garmin uses barometric pressure and the elevation measurement doesn’t work well in wet weather. 

 Uluru 18 Apr 2023
In reply to Cusco:

I have this on most rides, my Bolt seems to consistently under record the elevation even compared to others on the same ride also using a Bolt.

As someone has said above, if you use Strava, you can click on the adjust elevation button and Strava will use data it has to adjust the elevation. 

OP Cusco 19 Apr 2023
In reply to Uluru:

Many thanks for all your replies which were interesting to read. 

The tip about the elevation adjustment on Strava was good. The four Dartmoor Classic Medio route rides I’ve done are all now circa 6,700ft not 6,400, 6,600 and 7,000ft (the Dartmoor Classic website says the route is only 5,600ft).

Oddly though the Strava adjustment has increased the Dartmoor Classic Grande route ride I did from 10,600 to 11,200ft (the Dartmoor Classic website says the route is only 9,200ft). The former feels more like it rather than the latter. 

But it’s useful to be able to compare the Bolt reading to the Strava adjustment. 


New Topic
This topic has been archived, and won't accept reply postings.
Loading Notifications...