Electronics, Lighting, & Gadgets - Edge 705 speed and wheel calibration settings

Ok so I was an early adopter of the 305 and now have recently gotten a 705. I have the 705 all setup with 2 bikes and 2 cadence sensors...no problem pairing them.

My first question is the auto calibration of wheel size...does it always display 2100 for that value? Mine is for both bikes and did even before I rode the second bike. Unlike the 305 that told you it calibrated the wheel size I have gotten no similar notification on the 705 so I am wondering if it is working properly or if I missed something I should have done int he setup.

My next issue is partially related...how does this thing decide to use the wheel sensor vs GPS position for speed? I was on a ride yesterday and was on a stretch of road that had pretty dense tree cover...my speed was clearly displaying too low but when there would be a break in the trees it would jump up. It was showing like 9 mph and then would jump to 16 and then back down to 9. I have also had this happen on climbs when I am out of the saddle and my body is over the unit...even to the point where it auto paused (set to 2 mph....and I KNOW I wasn't going THAT slow) and then restarted. Why isn't the unit going by the wheel speed in these cases when it is clear GPS signal has been compromised?

Is this a setting some place I can change?

Don't quote me, but I think default is 2100 and it will calibrate itself in the first 500 miles to the "appropriate" size based on GPS signal and distance.

It uses GPS until signal is completely lost, then switches to the sensor. You will still have a good average speed because it takes distance/time.

So it needs 500 miles on each bike...that doesn't make a lot of sense.

Also I know the 305 works as you state about the GPS signal but the word being spread on Motionbased is that the 705 uses the sensor for instantaneous speed readings...which mine clearly isn't doing (which I suppose makes your statement true).

Thanks for the response...what it comes down to is there is a lot of conflicting information out there about how this thing is actually supposed to work.

Ok so update here. I checked my 305 and my wheel sizes are this:

Merckx: 2056 (Vittoria Corsa tubulars)
Bottecchia: 2087 (Vittoria Rubino Pro Slick clinchers)

On two occasions now, my 705 has shut down (not battery issue) in the middle of a 40-mile or so route and when I turn it back on, the average speed has jumped up to something like 47MPH from what it was, maybe 15 or 16 MPH. Not sure if that is in any way related to the above problems. Anyone else had this happen?

Oroluk - never had that happeen...sorry...well no I'm not...I wouldn't want to have that happen...but sorry you have that issue.

Back to my dealings. I input the wheel sizes from my 305 as listed above and the unit seemed to be reading speed differently for sure...speed updates came faster and seemed more consistant. I will have to do a wooded ride to see for sure but I believe the custom setting has this issue fixed.