@patliean1 in his video talks about the seatpost slipping despite very high tightening torque. I'll try to explain what could be the cause and how to fix it. The seatpost clamp is designed such that the part that presses against the seatpost has a limited forward extension. The opposite part of the clamp rests against the frame. If the seatpost seat is too large, the clamp won't be able to securely hold the seatpost when the bolt is fully tightened. This will be indicated by a high tightening torque and a large gap between the seatpost clamp and the seatpost or frame, depending on the clamp design. The VB-TT-023 frame uses the same seatpost and clamp, and everything works perfectly with a tightening torque of just 4.8 Nm for a rider weight of 73 kg. My TWITTER bike initially had large gaps, and they've gotten even larger over the past three years, causing the seatpost to slip. I added a soft metal spacer between the clamp and the frame (three layers of 1.4 mm each), and it's helping so far. I think this is a universal solution for any frame. However, VB should adjust their manufacturing process and better control the seatpost mounting space, IMHO.
