Garmin Forerunner 305

[ahollow]

OK, so this isn't specific to a unicycle, but it's a great device for training or tracking your progress. This model does the following and more:

GPS tracking
Speed
Distance
Time
Elevation
Heart Rate
Averages of all above
much, much more that I haven't played with yet.

It also allows you to upload your history to a website for display, including actually tracking your time/speed/location on a street map.

I rode Saturday up and down our Main Street, since it was closed a few hours ahead of the Saint Patrick's Day Parade. I wore green, and a big floppy green hat, so the police thought I was part of the parade and didn't bother me.

I started the Garmin when I left home, and let it run the whole time I was out. I logged 7 miles in the 3.5 hours I was out, including watching the parade, talking to all the people watching the parade, etc. I then uploaded all this to the following website:

http://trail.motionbased.com/trail/player/2165928

If you do look at this, click "Large" and "Hybrid" on the map for better detail, then click the Play button to follow my route. You can see my location, speed, heart rate, etc as I travelled for the 3.5 hours, including all of 40 min to watch the parade.

I'm hoping to take this with me to Moab, and post the routes I do daily.

[dbell]

glad you like the 305
i have the 201 (older less fancy model)
Its worth the money if you go for long rides a lot.

[jerryh]

I assume the delta in Total Elev Gain (1982 ft) and Total Elev Loss (-2005 ft) represents the margin of error in the accuracy of the GPS? If you started and stopped at the same location, wouldn't they be the same?

[john_childs]

GPS elevation data is less accurate than the 2D location data. There is going to be even more variation in your elevation data than there is for the 2D location data.

To get a 3D location (lat, lon, and elevation) requires a lock on 4 or more satellites and those satellites have to be in a good geometry in the sky. If the satellites are all clustered in one area you'll get less accurate results. To get a 2D location requires a lock on 3 or more satellites. And the accuracy will depend on the geometry of those satellites in the sky.

If the geometry is poor the GPS may not get elevation data even if it has a lock on 4 or more satellites. The GPS gives preference to calculating a good 2D location over giving you elevation data.

The cumulative elevation gain during a ride is never going to equal the cumulative elevation loss even though you start and end at the same spot. The accrued errors are just going to make that impossible. Same goes for your 2D location. You're going to end up at exactly the same 2D spot according to the GPS even if you are standing in exactly the same spot at the beginning and end of the ride. The GPS saying you're off by about 20 feet would be normal.

You can get a GPS that includes a barometric altimeter for more accurate elevation data. The altimeter will continue to get elevation data even when the satellite signal or geometry is poor. The GPS will can the satellite elevation data to calibrate the barometric altimeter. The barometric altimeter is susceptible to error when the pressure changes due to a front moving in. So even with a barometric altimeter you aren't going to end up with the cumulative elevation gain equaling the cumulative elevation loss. There is still going to be error.

Every consumer GPS has error in 2D location data and elevation data.

The Forerunner 305 is a good little unit. It has an updated GPS chip that is more sensitive than the previous generation. But it's not going to be magic. It's still going to have error, but likely less error than the previous generation of Garmin GPS devices.