sowe34

I did a 34 mile bike ride the other day in Western Connecticut. Mapmyride showed it as an 800 ft ascent, while Bikely rated it at 2400 ft. Which should I look at as being the more accurate of a source?

WheresWaldo

I couldn't tell you if Bikely is correct, but I can tell you that MapMyRide is wrong 100% of the time when it comes to elevation.

figgskzoo

I mapped an out-and-back centuy on MMR yesterday and the elevation profile was totally asymetrical. So, I agree with Waldo.

gurana

This has come up dozens of times the last couple of years. While I don't believe that either of those two sites are particularly accurate, I have noticed that the way you enter in the route can have an effect on the elevation it reports back to you, which might be a reason for the 1600 ft discrepancy over your 34 mile route.

Bikely seems to only calculate elevation at the points you select on the map. So if you were to select two points along a straight line that went up a hill, and back down to your starting elevation, it would not count toward your total elevation gain for that distance. (look at the elevation profile here for an example) The easy fix for this would obviously be to add more points along your route. The 'auto-follow' might put in enough to compensate for this, but I think that this would only be true if the road you were following had a sufficient amount of turns.

mapmyride appears to calculate elevation somewhat continuously between points. I made another example here, that resembles the first one. As you can see, the elevation profile appears to follow what's under the line, and not just the two points I entered.

In my opinion, mapmyride has the better system, but that doesn't guarantee that it is more accurate. People have posted various comparisons of both of these sites to their GPS data, and neither seemed to come out consistently more accurate than the other.

johnny99

The cumulative elevation gain feature of both web sites is completely bogus. Same is probably true of all freebie on-line mapping web sites. Their elevation and road data is just not detailed and/or correlated enough to calculate a useful cumulative elevation gain along paved roads, especially if your route involves short hills (less than 1000 feet at a time).

milliron

Bike Route Toaster will at least give you a decent idea.

https://bikeroutetoaster.com/

RacerMike

I took the CSV data from your example and its actually ~840 feet of climbing from point a to point b. I'm not really sure what mapmyride's numbre of 209ft of ascent actually refers to. Similarly, the CSV data shows ~921 feet of descending while mapmyride shows 307 feet.

mattm

it's all relative anyway - just use the same site all the time and you can at least compare #'s... i mean what would you do differenty with different gain numbers anyway? would you not ride a route if it's above a certain amount?

also it could be that bikely is using different elevation data than mapmyride (which presumably uses the same USGS data that i use for veloroutes).

i think people forget that these mapping sites are just like anything else on the net - take it with a grain of salt!

johnny99

1. The cumulative elevation gain numbers are so inaccurate that comparing 2 different rides may not be meaningful unless there is a huge difference. You'll get a much more accurate comparison by looking at the graphical elevation profile and counting the number of hills on each. The one with more hills is usually harder.

2. The problem is the way the web sites attempt to correlate road position data with the USGS elevation data. Both data streams are too sparse and don't align very accurately.

3. The reason people study elevation profiles is to help budget their energy on a ride. If you know there are 4 mountain passes on a route, then you really do not want to burn all your energy before the last mountain.

mattm

1) i just meant that if you're using the same site for your routes, then whatever inaccuracies exist in that site will be applied to all of your routes. so, in theory, so you can compare them. that's what i do anyway, since i don't own a GPS device.

2) how else could it be done? the user clicks at a certain lat/lon, and the site in turn asks the USGS for the elevation value at that coordianate. on their side they are probably averaging out their readings to give you a number. i'm not sure how this could be improved unless the USGS mapped out the globe at a higher resolution.

3) i agree, and any of said sites would show you the correct profile, it's just the totals that you should be suspicious of. from google maps' new terrain maps you can see the elevations values on the map, so you could double-check the max-heights, at least.

overall my point is that if anyone ever says to me, "i would have finished the route, but site X said that there'd only be 3k feet of gain! and there was 4k!" i'd probably slap 'em, or at least laugh.

johnny99

1. False. The errors will be different for different roads.

2. The user should not have to click on lat/lon. The user is riding on roads, not points. The user should click on the roads they are using and the computer program should accurately determine the elevation gain along the actual road. Mapmyride does have a "follow roads" option that is supposed to work like this, but their road data is not accurately correlated with their elevation data, causing huge interpolation/extrapolation errors.

I'm not saying that the problem is easy to solve; otherwise they would have done it already. I am just saying that the cumulative elevation gain numbers that these programs give you are ABSOLUTELY WORTHLESS. I never look at the numbers and certainly will not tell anyone that they are in any way useful.

LanceFanBoy

We're building the BikeWire Mapper right now, and while your points work in theory, they just can't be applied to the technology available online or provided by the government. USGS is the only service that will allow free data transfer with their topography numbers. We haven't been able to figure out how MapMyRide does their interpolated elevation graphing, but like you said, it doesn't seem incredibly accurate.

If you apply the same interpolation to the USGS function, it takes forever and eats bandwidth. Thus resulting in the gmap-pedometer and bikely system, where it only retrieves elevation at the selected points to allow for less bandwidth = faster response and "technically" more accurate if points are added in a diligent manner. And your GPS, doesn't keep track using roads, it keeps track logging lat/long every 1-5 seconds, which results in tracing the roads, while I don't expect anyone to click along a route that many times, the idea is the same. Like you said though, if it was possible to offer system that was completely accurate and fast, it'd be out there. Trust me, we've been searching haha.

I think we all agree though, the mapping systems online are only meant to be guides with loosely based ideas of elevation and distance. They are more for reference than training information.

teterider

While were listing these sites, I really like https://www.mapitpronto.com for creating and uploading my route to my Garmin Edge. It can save directly to .crs format, and has follow the road ability. You can turn on the elevation graph, it will give max and min elevations on the course, and at the top will give elevation ascent and descent figures.

AJU

I have found MMR to be fairly accurate, but you have to be aware of what you are looking at. The .csv file contains elevation at the coordinates for each interval (determined by the overall length of your route - unfortunately, the longer the ride the larger the interval) and you can determine the actual total ascent and descent values with a simple formula. What MMR does is uses an algorhythm to weed out the insignificant gains and losses in altitude, which in my opinion significantly understates the actual climbing done. I've had rides where the ascent value is less than the difference between the max and min elevation.

In my experience the elevation profile matches very closely that of my GPS (which I expect is LESS accurate than what I'm getting from google maps sources).

Godwin

I'm fairly sure both sites get their elevation data from the same place, google, so if you create the exact same route in each they should be the same. Mapmyride would probably be slightly more accurate as it has the follow road option so you're route should stay on the road and not slightly over a cliff for example.

johnny99

I think unless you can build a better product than the competition, there is not much point in your product.

Free data is worth every penny. If the data is not detailed enough to be useful, you should think about paying for a better data source. That will increase your expenses, but also increase your functionality and thus your customer base.

johnny99

The accuracy of the way they correlate road position to elevation position makes a huge difference when your road is traversing a steep hillside. Also, the different web sites use different interpolation and smoothing algorithms that have a big effect on their results. I have a tried a few of the mapping web sites and the cumulative elevation gain numbers for the same route vary widely. One web site might report 2 or 3 times as much as another web site.

urbanknight

Well put. They don't account for grading, cuts into the hillside, tunnels, etc. I have been told that they are commonly off by as much as 20%, but the OP's variance is quite a bit. That's like accidentally drawing the route down and back up a cliff or three.

mattm

and in fact, mathematically this is probably what happened. sometimes the USGS decides to return 0 for an elevation that has a real value, and a simple "total gain" algorithm will then subtract the last value (say 1000) from 0, thus giving you a gigantic difference. (when the current value should be 995 or something)

so i had to code around this in veloroutes, i skip a value if it's just 0, and use the last (good) value that the USGS gave me. not perfect, but better than what it used to be, and hopefully better than what some of the other sites use.

and as for getting your own datasource for elevation, it's not as easy as it sounds. you can download portions of the USGS database, but translating those pieces into a complete SQL database is no easy chore, and you'd have to do it 100's of times. there are smaller db's of elevation (like NASA's Shuttle Radar Topography Mission), but the resolution on those is every 100 meters or less, so it's not really fine-grained enough to please all the number crunchers.

when/if google releases their database of elevation (like what they use for Google Earth), then there's a good chance of all of this data being much more reliable.

gurana

Yea, I don't know what's going on with mapmyride. Like I said, I think theirs is a better system, it's just too bad that it doesn't seem to be accurate... or even make sense. I believe the line I drew is generally all down hill. I'm sure there might be some upward movement along that, but 840ft? It's too bad, because I like their interface and their ride finding features.

You know, when I figured out what was going on, I tried to re-do a route I made in bikely. It was about 58 miles or so. I turned off the follow roads feature, and just put in a bunch of points. I'm not sure, but if I had to guess, I probably put in a point every 50 yds or so. There was a lot of points. Unfortunatly, it ended up being so many that it either didn't save right, or I wasn't able to open it up after I did save it. Bikely just got hung up on it.

johnny99

The FAQ on the mapmyride web site says that their elevation data is not accurate enough for small hills, so they just ignore climbs of less than 200 meters (600 feet). That is why their cumulative elevation gain is always much lower than what an altimeter would tell you.

Other web sites will accumulate every single elevation change that their database reports, even "hills" that do not exist in real life. These web sites will report cumulative elevation gains much higher than your altimeter.

Unfortunately, the errors caused by these databases and interpolation algorithms will be different for different roads, so you can't just multiply by 2 or divide by 2 to get more meaningful results.

LanceFanBoy

You probably haven't checked out BikeWire yet, while I see your point, the objective of the site isn't to out-do every service out there (especially since we make little to no money from the site) it's to offer all the current services within a better interface and strongly tied together through networking and user based content. 80% of BikeWire users don't race an/or even put in elevation when they log their rides anyways, so the pinpoint accuracy of elevation is less important than the ability to browse friends maps, maps in areas, maps for clubs, etc.

I'm not sure if you saw that I also typed we couldn't find a better service (free or not) if you can, please post or PM me, because we stopped wasting time on it, just had more important things to spend time on.

tford

One other mapping site to take a look at is www.roadbikerides.com. You may want to compare the elevation on www.roadbikerides.com as well.

Here is the FAQ for their reason as to why the elevations are not always accurate.

www.roadbikerides.com/faq/questions/23/How+accurate+are+the+Elevation+Profile+and+elevation+totals%3F

LanceFanBoy

BikeWire Mapper is released (not to 100%, but fully functional and the extras are on the way soon). Check it out. From the feedback we've gotten so far, its faster than all the other apps with less clutter and the application within our site is pretty popular.

https://www.bikewire.net/mapper.php