The FR245 is Software 11.6 The FR 265 is software 19.18
Before the run I checked the resting HR wearing one watch on each wrist. The 265 updates much faster and the reading moved around a lot more but at quiet rest both settled into essentially the same HR which I compared to manual count I made, taking my own pulse. Though because of the 265's faster updates it was hard for it to be a totally apples to apples comparison, but they were close.
Then I wanted to see how the readings might compare if they were more averaged over time, I could have worn them around the house but better I though to go out for a (mildly wet conditions) run, again one on each wrist.
The two graphs are remarkably similar with the exception of how the 265 ramped at the start and for the recovery after two short stops towards the end.
They both averaged the same 151 BPM with the 245 showing an absolute HR max of 262, a single BPM higher than the 265. To my eye, at least for the software versions I used, for the start and after the stops the 245 looks more accurate, taking less precipitous leaps to get back to the HR for the pace being run. If I'm correct, software would seem the likely culprit.
Overall stats they were dead on with the exception of elevation, the 265's barometric sensor logged 194 FT, compared the 245 GPS logging 117 FT
Pace time was identical.
There was some variance in the 1 mile lap times but obviously they averaged out in the end since the pace times are identical. The GPS sensor setting are on the defaults for both watches.
265 245
Mile 1 8:22.1 8:29
Mile 2 8:17.3 8:14.6
Mile 3 8:19.8 8:16.6
Mile 4 7:52.1 7:51.6
Mile 5 8:09.5 8:02.8
lap 6 the 245 was 5 seconds/mi slower but it was a very short lap.
The other stats as reported by both, cadence, stride length, SPM matched.
The anaerobic vs aerobic stats are close but not identical, The 245 did log 1 beat higher for the max and that might be the difference since those beats are at the higher end for me..
aerobic anaerobic
265 4.2 0.8
245 4.3 1.3
The user profile is the same on both, Max HR, Age, Weight
Both show the same VO2 Max.
