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Can any one let me know what is the exact use of GPS/Elevation on Bike computers (EDGE 500,510 or TIMEX 2.0)?

I ride with a SIGMA BC 16.12 (with CADENCE) and POLAR HRM. I check my elevation using STRAVA.

One reason that i can think of is

all these data collated onto one graph for post ride analysis.

Apart from the above reason, is there any advantage of GPS/Elevation detail during the ride?

Thanks

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Ever had that "this has to.... be the top.... oh sh$%.... it's a crest.... there's more...." feeling. Knowing altitude lets you pace your climb and arrive the the top without over (or under) doing it.

Imagine riding flat roads without knowing speed or distance - it can be done, but to maximize training effort or race performance you need to know speed/distance on the flat and altitude/climb rate on the hills.

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Historical Contingency

Looking to history earlier versions (e.g., Garmin Edge 305 and Edge 705) came with barometers for elevation. This was long before Strava, and during a time when you did all the analyses on your own computer. Some analysis software supported getting elevation data from other sources, others didn't. And at the time accurate and free elevation maps were not as ubiquitous. In terms of marketing, when you release the next generation of devices (e.g., Edge 800, 810, 1000 etc) it may not look good removing features as people love to compare specs without thinking about why they may need a spec.

Some Real World Uses

When I used to race, I found getting real time road grades helpful. One example that stands out was a long false flat on one course (a false flat, looks flat but has a subtle elevation gain). Physiologically it was demoralizing. I found being able to confirm I was on a false flat by looking at the grade output helped greatly as it gave me the confidence to attack hard even though I felt slow. The attack proved instrumental, securing a solo breakaway win.

In touring I loved being able to track my total elevation gain for the day. It helps to put a slow day in perspective (if you are trying to cover large distances), or tuned me into cutting a day short due to the volume of climbing. Often you don't have access to the internet camping so real-time elevation can be useful here too.

Conclusion

Apart from these reasons there is no one overwhelming reason (IMHO) to insist on having a barometer with a GPS computer, but that said it can be nice to have if it is there.

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    One other reason it's good to have a barometer for elevation measurement is that GPS measurement of elevation is ridiculously inaccurate. It can be off by 10s of meters at any given point, and often is. And even though you can get geographical elevation data for a given route, that too is much less accurate than a barometer. – Carey Gregory Oct 29 '14 at 1:11
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    @CareyGregory - You should see mattnz comment on another question in this thread about barometric measurement being prone to drift. I have experienced this discrepancy on longer rides that loop. – Rider_X Oct 29 '14 at 4:14
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    Barometric measurements drift over long periods, but are quite accurate over short periods. My altimeter for my GPS will change by 1 meter if I move it 1 meter up or down. So it's great, as @alex pointed out, for telling you your instantaneous climbing speed and other important metrics while riding. It's also going to be pretty accurate telling you how much climbing you did on that hill you just spent 15 minutes climbing. It's not going to be completely accurate giving you the height above sea level you are currently standing at, even though that's technically what it's trying to tell you. – Kibbee Oct 29 '14 at 13:23
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I find when climbing that horizontal speed is fairly meaningless but vertical speed can be quite helpful for keeping you going and/or interesting.

When you know a climb is 1000m and your computer says whatever-kmh, you've no idea what that means without maths and knowing the gradient, 1000vmh means an hour to go, 500vmh, 2 hours... and so on.

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If your GPS bike computer doesn't include a map[1] and you're navigating from a topo map, having the elevation can be very useful for making route decisions.

In the bad old days before ubiquitous GPS, by far the most useful navigation tool in the mountains for me was a barometric elevation watch. That and a topo map was my go to tool 90% of the time.

Of course, if you're not in the mountains, it's not much help.

[1]- Or even if it does, most bike computer GPS displays don't have enough detail for when the going gets tricky in the mountains.

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In addition to the answers above, vertical measurement increases the gps accuracy of your x/y coordinates. If a GPS unit has terrain data stored, it will be able to have a more confident match for its stated x/y coordinates based on the addition of that extra altitude variable. For example, if the unit has two possible coordinates for you, one being a 55% match and the other being 45%, then you will get placed at the first point with low confidence. If the altitude of those two points matches closely to your altitude variable read, then the unit can select a point with much more confidence.

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    Consumer GPS is typically accurate to 10 meters 90% of the time. HDOP regularly drops below 5 meters. On most roads people cycle, altitude variation over 10 meters will rarely exceed 1 meter. Barometric altitude measurement is prone to drift due to weather and temperature affects sensors - in consumer devices error of barometric altitude is typically 5 to 10 meters and can exceed 100 meters after a couple of hours in extreme weather events. It offers no useful information for GPS accuracy. Anyone claiming it helps is selling snake oil. (Extremely mountainous terrain is different) – mattnz Oct 29 '14 at 1:44

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