i use the tickr from wahoo, their site shows it at $50, but i think i got it for $40 on sale.
i highly recommend using an HRM indoors. it made a big difference in how i approach a ride, and i think it improved my strength and my enjoyment of each ride.
before i had the HRM, i would ride without any real idea of how tired/maxxed out i was. eventually, i’d hit a wall and then i’d soft pedal for the rest of the ride. it wasn’t very fulfilling.
after the HRM, i now know where my different heart rate zones are. i know what my max heart rate is, and i know that if i hold at my my max for more than a few seconds, i’m toast for the rest of the ride. i can sit in “threshold” for quite a while, and i can push hard up hills/in sprints while watching my HRM to see if i’m maxxed yet or not. if i’m pushing in a group ride, i can gauge whether i’m going to blow up or be able to maintain.
now, i only soft pedal when i purposefully maxxed my heart rate – but it’s all a known quantity! i mostly finish at tempo now, and it’s a lot more fun. also, some days i’m just not “on”, and i can see that before i have a miserable ride.