Bike Ride wrong mileage

[camphill]

I just bought a Garmin Legend. I cleared all tracks/routes and proceeded to take a bike ride.  At the end of the ride my bicyle computer showed 19 miles ridden.  I downloaded the track from my gps to my pc and loaded it intoTopofusion. To my surprise Topofusion showed I'd ridden 38 miles. I've ridden this route many times and know it's 19.  Any ideas why Topofusion showed 38?

[Kuren]

I'm not on the support staff, but I'm curious..  I bet they will ask you to attach your GPS log file.

What program did you use to download it to your PC, I see you say you did that, then you loaded TopoFusion.  Wondering if it's a file convertion issue.  

How far does Garmin's Mapsource report the track is?  Can you attach the GDB file from Mapsource?

I know sometimes Garmin will add one extra point to the track which draws a diagonal line from the end to the start.  Do you see that when you view the track?

Other than that, unless you live on the international date line or on the equator (which TopoFusion should handle fine now), I can't think of what the cause would be.

There are a couple of things that could be happening.

One is stray points, as Kuren explained.

Another is simply a tracklog from a previous ride (if you didn't clear the active log, or if you have saved tracks stored).  Double click on the file to zoom to show it all, you'll probably see some points you didn't expect.