The Monkey Bike is back! Honda Unveils The 2019 Monkey, A Grom-Based Retro That We Already Love.Honda’s original Z50 “Monkey Bike” debuted in 1968, and tens of thousands of people learned to ride on them. Kids loved the Z50 (and the Z50R, XR50, and CRF50 it evolved into), but so did adults. Now the Monkey is back in 125cc form. Based on the Grom, this bike is sure to be a hit.