Yes, the top tube. Your reach is very short, you look cramped up. Probably because you switched from drop to flat bars with a short stem. That bike is designed to have drop bars with 80mm+/- reach,
plus a stem of 100mm+/-. For the same size intended rider, flat bar hybrids and mtbs will have longer top tubes than their drop bar brethren. You could probably count your cadence over one minute of video if you wanted. Looks like you have a nice place to ride.
