By head unit, I meant the mounting bracket device that you zip tie onto your bar. It appears that if you get a good one, it works fine from the start given a good install of the sensors. A bad one either doesn't work at all or cuts in and out on you right from the first ride.
Your HRM is the receiver. As far as how much ride data it will hold, that depends on what functions you have activated, and how often you have your receiver set to record its readings. With mine set to track all possible data on the shortest possible intervals, I can get about the same number of rides as you are getting.
Your HRM is the receiver. As far as how much ride data it will hold, that depends on what functions you have activated, and how often you have your receiver set to record its readings. With mine set to track all possible data on the shortest possible intervals, I can get about the same number of rides as you are getting.