I have a Soleus Pulse GPS watch. great for running and general sports where you don’t use your hands.
UTTERLY CRAP for riding. moving hand positions, even tightening your grip on the bars means it reads your pulse wrong.
example:
On the cross bike, riding on the hoods, pulse at a steady 130bpm, move hands to the drops, pulse rate drops to 80bpm and i never managed to get it to read higher than 145bpm on the bike.
My chest strap garmin would show 160-180bpm for the same efforts.
Even the manufacturer said it won’t work for cycling and a chest strap is better when i contacted them.
I can dig the email out if you like?
Shame as chest straps are uncomfortable for the most part (well, Garmin ones are, my polar replacement strap is fine)