GPS Speed and Distance

[Caerus]

ooo, pretty beads. so is that what u need the string for? should make a purdy necklace...

 

Yip, they are custom order for him

[Capricorn]

Yip, they are custom order for him

 

pray tell how to use em.. or would any version of The Hangover suffice?

[johnw]

Most GPS units come with Speed / Cadence sensor (or at least the Garmin units do). I do not have to set my wheel size as the unit measures the distance measured on the GPS and self-calibrates the cadence / speed measurement. My understanding is that this improves the accuracy of the system. Anybody in the know to comment on this?

@morwoodMad, you have 2 choices on the Edge 500. (1) you can select "Auto" in the wheel size field so that the GPS calculates wheel size or alternatively (2) select "Custom" to enter the actual wheel size. Option 2 is more accurate as long as you get the wheel circumference correct.

[Caerus]

@morwoodMad, you have 2 choices on the Edge 500. (1) you can select "Auto" in the wheel size field so that the GPS calculates wheel size or alternatively (2) select "Custom" to enter the actual wheel size. Option 2 is more accurate as long as you get the wheel circumference correct.

 

I take it that you would measure the front wheel when doing this? The problem here is that you cannot enter a wheel circumference for a second bike on the Edge 500 itself, it can only be done via GTC or the like when setting up your bike profiles.

[Squier]

I ride with a sensor while my riding partner rides with a GPS. Over a 90km ride there is almost 3kms difference in our total distance readings.

 

My question is; does the GPS take the weaving accross the road into account? No one rides in a perfectly straight line, right...

[rouxtjie]

I find the GPS more accurate to be honest, that is why the speed sensor for my edge 500 isn't even installed, I love that I can just plonk the unit in its bracket and off I go, no need to worry about magnets and foefies, it just works.

[Caerus]

I ride with a sensor while my riding partner rides with a GPS. Over a 90km ride there is almost 3kms difference in our total distance readings.

 

My question is; does the GPS take the weaving accross the road into account? No one rides in a perfectly straight line, right...

 

It does, I checked it the other day. It was picking up the slightest detours. I was pretty surprised in fact. I've got it set to take a reading evrey second. It could be that possibly the reading are not done often enough thats giving this differance.

[scotty]

My GPS is also pretty accurate when compared to routes iv'e done with sensors. I don't need to know how far iv'e ridden till to the last cm.

[Benjamin]

I've never understood how a GPS can be accurate for distance and speed when taking altitude into account. To my understanding , gps coordinates are 2 dimentionall ie latitude and longitude, and on a flat plane can be accurate to mms , but if you go up in total elevation, the distance from point A to point B will be more ( remember trig at school?) than if you rode along a flat plane. So does the gps unit have a built in altimeter which it references or does the thing actually work in 3 D?

Edited February 15, 2012 by Benjamin

[EZRider]

I've never understood how a GPS can be accurate for distance and speed when taking altitude into account. To my understanding , gps coordinates are 2 dimentionall ie latitude and longitude, and on a flat plane can be accurate to mms , but if you go up in total elevation, the distance from point A to point B will be more ( remember trig at school?) than if you rode along a flat plane. So does the gps unit have a built in altimeter which it references or does the thing actually work in 3 D?

 

GPS units are 3D. Their triangulation allows them to calculate spatial orientation in all planes.

My Edge 500 also has a an altimeter.

[Minion]

I've never understood how a GPS can be accurate for distance and speed when taking altitude into account. To my understanding , gps coordinates are 2 dimentionall ie latitude and longitude, and on a flat plane can be accurate to mms , but if you go up in total elevation, the distance from point A to point B will be more ( remember trig at school?) than if you rode along a flat plane. So does the gps unit have a built in altimeter which it references or does the thing actually work in 3 D?

According to school trig, a 100km ride up a 10% gradient (eish!!) would result in a difference of only 500m if one was measuring true distance and the other horizontal distance.

 

 

 

I take it that you would measure the front wheel when doing this? The problem here is that you cannot enter a wheel circumference for a second bike on the Edge 500 itself, it can only be done via GTC or the like when setting up your bike profiles.

You'd measure whichever wheel the speed magnet is attached to (rear if using a Garmin sensor). I think the setting is buried somewhere under the individual bike profiles (or it is on the Edge 800, at least).

[Rob22]

I've never understood how a GPS can be accurate for distance and speed when taking altitude into account. To my understanding , gps coordinates are 2 dimentionall ie latitude and longitude, and on a flat plane can be accurate to mms , but if you go up in total elevation, the distance from point A to point B will be more ( remember trig at school?) than if you rode along a flat plane. So does the gps unit have a built in altimeter which it references or does the thing actually work in 3 D?

 

GPS system do calculate 3D and do take altitude into account.