In GPS We Trust: Runner threatens law suit over course measurement disagreement.

because it's a helluva lot harder to gauge pace on the road than it is on a track when you know exactly how far you've gone in a given time. plus spikes.

I've owned my 405 for a couple years. What I've learned is it could be off by up to .25 over 10 miles in some cases, it doesn't like trees, and it doesn't respond well to rapid pace changes and surges.

The wheel is the way to go, it just takes forever.

Test stand start your garmin, start swinging your arms as if you were running - but your still standing your garmin will start racking up distance - how is that distance factored in when you really start running ? Could that swinging distance be the cause of innacurate readings in the end ?

luv2run wrote:Never heard that one. Hope I can remember it. I love corny/bad old jokes.

(note, some suspension of disbelief is required)

Pythagoras is walking down a road and comes across a squaw sitting on a deer hide holding one papoose. He finds this interesting, but continues on. Later he passes another squaw on a moose hide holding two papooses. He's intrigued but continues on his journey, but then he comes across a squaw on a hippopotamus hide holding three papooses!

Valla! He's got it! The squaw on the hippopotamus is equal to the sum of the squaws on the other two hides!

"Valla!"? You're Keith Stone, so smooth.

http://www.youtube.com/watch?v=kLStB-0K-jQ

xxxrunnerxxx wrote:

Why do you think the world record on the track is always faster than on the road?

Not sure why you're posing this query to me but I'll give it a shot: track surfaces are rubberized, providing a 'bounce-back' sensation, spiked shoes provide grip, dead flat, line to follow is simple to follow, splits every 400m. This can vary but might be part of equation: wind might be less a problem in stadiums.

GPS = Geek soother

Just as a baby needs a pacifier to calm itself, geeks need GPSs. Just run.

roadvstrack wrote:

The wheel is the way to go, it just takes forever.

Not true. Surveyor's wheels are not only slow, but inaccurate, for a number of reasons.

Which is why certifiers use a calibrated bike. Faster and more accurate. I won't go into the details as most people here probably know them or can find them online, but even w/ 2 rides I can measure a course in the time it takes someone to run it, or less.

JimG wrote:

roadvstrack wrote:

The wheel is the way to go, it just takes forever.

Not true. Surveyor's wheels are not only slow, but inaccurate, for a number of reasons.

Which is why certifiers use a calibrated bike. Faster and more accurate. I won't go into the details as most people here probably know them or can find them online, but even w/ 2 rides I can measure a course in the time it takes someone to run it, or less.

Unless it's a cross country course.

You Sound Knowledgeable wrote:

JimG wrote:

Not true. Surveyor's wheels are not only slow, but inaccurate, for a number of reasons.

Which is why certifiers use a calibrated bike. Faster and more accurate. I won't go into the details as most people here probably know them or can find them online, but even w/ 2 rides I can measure a course in the time it takes someone to run it, or less.

Unless it's a cross country course.

No, you can use a mountain bike and get pretty accurate results provided the course doesn't have ridiculously hard hills or surfaces. Still, it won't be as accurate as on the road, which is one reason XC courses aren't certified (although the main reason is the lack of permanent, well-defined course boundaries).

Please, please, may we not go down the xc measuring saga again!

In regards to the GPS vs. bike method (JOnes Counter):

I have not done any scientific studies but I have made some observations that might help with the discussion.

I have a Garmin GPS 60CSx mounted to the handlebars of my bike. I use it when I'm measuring my courses to give me the approximated distance when I need to look down at the JR counter mounted on the axle for mile/km points. It's a great tool (+ all of the other great nerdy data it gives!)

I have observed the following

- On roads without adjacent large trees or buildings, the GPS is consistent with the JR Counter with readings of 1.00 to 1.01 miles.

- On Roads with adjacent large trees or buildings, the GPS could range anywehre from 1.01- 1.02.

Theses observations are consistant regardless if the road is straight or undulates!

The difference is increased if the course has a great deal of sharp turns.

I ge the same readings confirming the differences between the GPS and JR Counter with the second measurement of the course.

Just a side note.

Several years ago I observed a very unusual situation when measuring a marathon. I used the JR Counter with the assistance of a bike cyclometer with a wireless sensor mounted on the spoke.

The cyclometer had always been consistant with readings of 1.01 miles compared to the JR Counter. But, with this measurement I was getting a very different reading between miles 11 and 12....inconsistant. I measured that same mile over and over with the same crazy results. Than I decided to measure just segments of that mile. What I found out was that some type of signal was being broadcast from a house adjacent to the course altering the reading on my wireless cyclometer.