RISK Bicycle Bike Seat Cushion Height Measuring Tool Fitting Measurement Gauge Saddle Tool

I first level the bike by putting it on the turbo and using a level across both axles. I then set a laser level up, ensuring it's square to the bike by making sure bb centre and pedal centres top and bottom all line up. Then use a cheap Ali express seat height measuring tool to measure from that to a consistent reference point. I've found this to be infinitely more repeatable than using a plumb line, which could be poor technique but none of my bikes have a clean line down from any part of the saddle past the bb, then you have variation of picking centre point etc.