I've started to think I should pick up a HR monitor as well. I would like to see what my HR is when I'm pushing it. I've never run into the situation where I feel like crap later. But then again I am riding a ebike. I will ride hard enough to get fairly spent, but never enough to feel like I'm pushing my limits.
Do you guys use the HR chest straps with Bt? They seem fairly cheap and would work with my phone.