I hit a 350ft no wind HR off a tee with BBCOR bat, but Zepp says my bat impact speed is 52mph, with a max of 60mph. Weird? I only swung 70mph with a BESR so I think it's accurate.
from my experience zepp tends to be really off. One swing I had a 70 mph bat speed and the next 81. Same technique and mechanics, I think diamond kinetics is the big deal now