If you want heart-rate data but don't like wearing chest straps, then the Wahoo Tickr Fit could be a good solution. The small unit wraps around your arm and connects easily to bike computers and smartphones on ANT+ and Bluetooth. The data tracks well against a traditional chest strap.
My initial reaction to this product was, 'This is for runners. It's dumb for cycling'. But, for indoor riding, it has proved convenient for me, eliminating a sweaty layer on the torso. I do Zwift in my garage with a MacBook Air laptop, and the Tickr Fit's Bluetooth connection is solid and doesn't require a USB dongle like ANT+ products do.
Also, my female colleagues have said chest straps and sports bras aren't always complementary, although you can get some excellent sports bras with monitors built in, so getting heart-rate measurement at the arm could be handy there too.
I tested the Tickr Fit against a traditional heart rate strap and it tracked along nicely. Not that consumer-grade heart-rate chest straps are exactly flawless, but the Tickr Fit seems just as good as what many of us have been using for years in terms of data collection.
Unlike a chest strap where you wet the sensors then put it on and hope it connects, the Tickr Fit has a single power button. Once depressed, the LEDs flash green on the skin-facing side. Externally, the Tickr Fit flashes blue when connected and red when there is something wrong, such as the unit isn't pressed against the skin.
While the design is very easy on bare arms, it's a little fussy when worn underneath a layer. The Velcro strap can snag on a baselayer or jersey as you pull on the sleeves.
Wahoo suggests wearing it on the forearm, but I wore it above my elbow. It seemed more comfortable and secure there.
The Tickr Fit comes with two sizes of bands that adjust in size with Velcro.
Claimed battery life is 30 hours, which was in line with my experience.
The USB-rechargeable battery is a double-edged sword: it's nice that you don't have to replace any batteries, but it means you have to keep track of yet another product-specific USB cable.
An increasing number of chest straps are ANT+/BT compatible now (including the original Wahoo Tickr), so the Tickr Fit doesn't have a monopoly on the dual-band broadcast. But it does stand alone, for now at least, as a way to get heart-rate data without a chest strap or watch.