A simple test is to manually measure your resting heart rate. Just put two finges to your neck or wrist and measure the pulse. While looking at a clock, count how many tiems you feel a beat in 1 minute. Then compare that to your resting heart rate as measured by your heart rate monitor.
Also, you might want to use electrode gel to improve contact as poor contact may result in poor heart rate data.
As for heart rate maximum formulas, I've also used them and when riding at zone 5 (95-100% of max), I didnt really feel like I was putting out my maximum effort. And herein lies a problem. Those formulas are just formulas. They don't always give you YOUR maximum.
Last edited by WK95; 06-09-14 at 09:09 AM.