If I want to bring my phone with me, it has to be in airplane mode or it messes up the reading. Last night I put my keys in my jersey pocket and my HR monitor numbers were all over the map. It ranged between 150 and 260 and just fluctuated wildly. I didn't ride last night with a saddle bag; would the keys in the saddle bag be far enough away to not interfere with the numbers? What do you guys do with your keys and phone so your HR monitor works correctly? It's really frustrating how finicky these things are.

It's a Garmin HR strap that came with my 500. I got it a month ago.