anyone got an idea what to set the recording rate to on a polar 720i so I can capture a whole IM, hopefully about 13 hours worth? 15 seconds or 60??
15 second interval should get you what you need.
5 second interval is just shy of 14 hours.
When you go to memory mode to make the change the display tells you how much memory time you have left for each setting. Best to have it empty at the time (no files saved). Also those limits change if you have bike settings turned on. The polar manual gives a table of what the limits are depending on settings. I believe things like cadence,speed,altitude alter the limits. But easiest thing to do is just go to the memory setting and change it from 5 to 15 to 60 and the monitor will tell you how much memory time is available.
Also avoid taking too many “lap splits,” as this chews up memory. Not sure how much, but it does make a noticable difference.
I prefer to use the lap button and hit it at the mile markers on the bike and run. Taking samples every minute or so seems like way too much information.
perfect , thanks people, I just ran for an hour this morning with it set at 60 and the chart looks like someone butchered it! all blocky. anyway over a full distance I suppose it will look better, I will try the 60seconds at vineman and see how that looks
Thanks for the help
glyn
15sec should get you there but you can’t be running the cadence or I’m pretty sure that’ll fall short.
I prefer to use the lap button and hit it at the mile markers on the bike and run.
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That must be tiring after about 50 miles in, Art 
Very funny. Mile markers on the bike are usually every five miles.
I thought so, seriously doesn’t this take your concentration away from the task in hand?
Not at all. I see the five mile marker on the course, I hit the button. This is once every fifteen minutes or so, and can also act as a cue to take a drink.
Having these splits is very handy. It allows you to compare your pace over the same sections of road. I keep a log of these splits for the Lake Placid course.