The "updated" 2019 JSL 20 is pretty much exactly the same as the 2018 model (just 7 speed, as opposed to 6 speed). 2019 is actually slightly heavier, but just ~250g). Momsen seem to be the only easily available light kids bikes @ about 8.5kg (using rigid fork) compared to the rest of the market which are about 10.5kg (but with front suspension).
