Originally Posted by
Nomad2
I actually measured it by using a long spirit level lined up on one edge to the centre of the bottom bracket and ran a tape across to the head tube at the location where the steerer emerges (well, the spacers at least)
Try the trick of using the wall and floor as reference points for the BB and head tube top center. It makes the measurement very easy. Also that same method can be used for transferring fit from one bike to another. Just prop up the bike perpendicular to the wall and floor with the inflated rear tire touching the wall. Make sure the front wheel is straight. You can use an indoor trainer stand to hold up the bike. As long as you have a shim for the front wheel to make the bike level, all the measurements will cancel out the height of the bike off the floor so you don't have to worry about that.
Sorry I didn't see you acknowledgement of my other post. But the trainer stand is a good way to do it.