As any regular reader will know, the Edge 800 has a bug where it will crash somewhere around 400k.
So you need to stop the recording, and reset the timer somewhere before that, and then splice the tracks together.
On a recent 600, I had the ride logically split into 3 200k-ish sections.
I re-set it at the 200k point, and the 400k point.
On the final stage, I got my knickers in a twist because I couldn't find the control.
The device was routing me this way and that; but my by reckoning we had passed the control according to distance.
I had pulled over, and was fiddling with the device to get it to show me the control waypoint, when an ACH chappie pulled up to check I was OK.
"Where's the control?" says I.
"Oh, it's about 10 miles on yet!" says he.
And so it was.
The device was routing me correctly.
The problem was that as you reset the timer, you need to keep track of the accumulated distance which you've just cleared, and add that onto whatever distance the device is currently showing.
It was just my mental arithmetic was not up to scratch at 550k, and I had got my current distance wrong.
Bah.