- News
- Reviews
- Bikes
- Accessories
- Accessories - misc
- Computer mounts
- Bags
- Bar ends
- Bike bags & cases
- Bottle cages
- Bottles
- Cameras
- Car racks
- Child seats
- Computers
- Glasses
- GPS units
- Helmets
- Lights - front
- Lights - rear
- Lights - sets
- Locks
- Mirrors
- Mudguards
- Racks
- Pumps & CO2 inflators
- Puncture kits
- Reflectives
- Smart watches
- Stands and racks
- Trailers
- Clothing
- Components
- Bar tape & grips
- Bottom brackets
- Brake & gear cables
- Brake & STI levers
- Brake pads & spares
- Brakes
- Cassettes & freewheels
- Chains
- Chainsets & chainrings
- Derailleurs - front
- Derailleurs - rear
- Forks
- Gear levers & shifters
- Groupsets
- Handlebars & extensions
- Headsets
- Hubs
- Inner tubes
- Pedals
- Quick releases & skewers
- Saddles
- Seatposts
- Stems
- Wheels
- Tyres
- Health, fitness and nutrition
- Tools and workshop
- Miscellaneous
- Buyers Guides
- Features
- Forum
- Recommends
- Podcast
forum
Variable height
I like to know how much height I climbed on a ride, and Komoot gives me that number. However my buddy, riding alongside, gets a very different number, consistently several times greater, from Wahoo. Last time Komoot recorded about 1000 feet, Wahoo gave over 3,000 feet, so not just a minor difference.
I understand that, a bit like measuring the coastline, you could get almost any figure you want, depending on the granularity of the measurement. Accumulate every imperfection in the road surface, every jitter in the GPS altitude reading, and you could be doing an Everest on the flat.
So I got to wondering whether there is any merit at all in the recorded figure. How do the algorithms work out what is a "valid" altitude gain and what is just a bump in the road?
I don't suppose there is a consistent answer to that, so as an alternative question:
Do you get vastly different altitude gains recorded compared with your mates on the same ride?
If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.
Latest Forum Topics
Latest Comments
- Martin1857 1 hour 13 min ago
I did a Cytech 2 course some years back with a mechanic from Wiggle who told me that he'd seen bikes in Halfords with the forks mounted back to...
- Backladder 1 hour 51 min ago
I don't disagree with you about drivers but surely the whole point of manslaughter is that there wasn't an intent to kill and what I saw on the...
- leedorney 2 hours 8 min ago
NEVER understood narrow shoes, never still I ever, Lakes all the way, even the Lake 333 is possible to get in wide, these no, poor show Decathlon,...
- jbuckx2 2 hours 13 min ago
Your right, it's not finished, but if this was road works (for motorists) would this be acceptable? ...
- Rendel Harris 2 hours 23 min ago
Well that's some pretty spectacular nonsense you've got going there. Everyone I know who uses Zwift is also a keen road rider with multiple bikes...
- David9694 2 hours 41 min ago
and we're all left squabbling over drivers' leavings as ever...
- Backladder 2 hours 59 min ago
But how many drivers are they actually locking up, they can barely be bothered to fine them!...
- Mr Hoopdriver 3 hours 17 min ago
Typically, for dodging a £2.00 ticket on the railway, fine will be £50.00 + prosecution costs of £hundreds. Same for private hire drivers picking...
- Backladder 3 hours 24 min ago
I think queues of traffic might be very vulnerable to a cyclist swinging a U-lock at their windows! Bring on the revolution!
Add new comment
13 comments
Barometric devices can also be put off by strong winds and rain in the hole that allows air through the case. My old Garmin 810 is not quite as bad with a rubber case fitted but still it's all quite approximate.
FOOLS!!!!!!!!!!!!!!!!!!!!!
YOU USE WHATEVER DEVICE / APP TELLS YOU IS THE GREATEST ELEVATION AND NOTHING ELSE!!!
Amateurs the lot of you...
Wahoo uses barometric pressure as does Garmin. What your seeing is pretty common although 3x is a bit much. Map data historically hasn't been that accurate for height so they don't use it.
Thanks, didn't know any used barometric height. Over a couple of hours in stable weather that ought to be fine, and presumably not be sensitive to every undulation. If anything I'd have thought my buddy's Wahoo should give a more conservative account than my Komoot (assuming it uses GPS), and yet it's the other way around. I'd like to get to the bottom of this!
Use a better quality barometric altimeter. My old Silva altimeter corresponds well to French IGN maps and is more consistent than my Garmin 520 for altitude climbed.
Just compensate for changes in the weather at end of ride ...
start altitude: altimeter 1100m, map 1120m
end altitude: altimeter 1200m, map 1250m
metres climbed: measured 1500m, corrected = 1470m
Er, I think your maths is off, so maybe it's not quite as foolproof as you suggested? In any case, what if the variation is in the middle of the ride?
I think jaysa is saying his barometer error drifted 30m (50 - 20) up of its own over the duration of the ride, hence he subtracts 30m from the 1500m measured accumulated altitude, which I suppose is the scenario you refer to of mid-ride variation?
Edit - I see mdavidford (below) has a point, my maths is also upside down!
But on the figures given, the measured altitude was 20m down at the start and 50m down at the end, so it's drifted down 30m compared to the map altitude, so they ought to be adding 30m on, not subtracting it.
What I meant by the variation being in the middle of the ride is that you could have 20m variance at the beginning, and 20m variance at the end, but 50m variance in the middle. On jaysa's reckoning, you don't need to apply any correction. But imagine that your ride is uphill to the middle point, and then downhill to the finish. In that case, you've lost 30m of your climb. Conversely, if it's downhill to the middle, and then uphill to the finish, it will have measured you descending 30m more than you did, and then climbing an extra 30m in the second half.
[I deleted my comment - it was rubbish]
The comparison to the coastline paradox is not really valid. The latter is a fractal issue: the more you zoom in, the larger the perimeter legth you will measure. With climbs, however, a profile that is monotonic at a given scale is liely to remain monotonic at fimer scales too.
I would bet the source of error in your mate's computer is an hilariously incompetent setup.
And likewise the more you zoom in to the road surface the more ups and downs you will discern. An ant walking what to us is a perfectly level road surface would nevertheless have to climb all of the chippings, up the north face and down the south. At a larger scale some algorithms might accumulate every minor undulation, others might have a higher threshold before they count a gain in height.
Anyway, I get that a GPS does not give that level of precision nor accuracy, however that might not prevent a poorly designed piece of software from accumulating every oscillation in the GPS output.
Komoot returns different answers for elevation gain over a planned route and the same route actually ridden. So I guess on the planned route it uses map elevation data whilst on the recorded (same) route it uses GPS. Seems odd, but there you are.
Still curious whether others experience significant discrepancies in elevation gain between different riders' devices in the same group ride.
I think up to about 10% in my gang.
I think GPS devices typically only record one data point per second, so that will certainly smooth out every little jitter to some extent. I also imagine the accuracy of the GPS device is also a bigger source of spurious elevation gain than genuine height differences - the uncertainty in the measurement is almost certainly significantly larger than the height of an average speed bump.
I normally only look at Strava (rather than comparing the raw outputs from people's various devices), and generally notice some differences in height but generally far less significant than what you're reporting - maybe +/- 10%. Strava has some info on how heights are calculated and presented that may be of interest, although the fine details might not apply to other platforms: https://support.strava.com/hc/en-us/articles/115001294564-Elevation-on-S...