Originally Posted by
Kontact
The problem with this method is that it relies on your accurate judgement of the bubble being truly centered, and you have to do that twice - once for table and once for the fork, which doubles your possible error. I'd suggest taking the level part out of it:
It would be better to place an object under the steerer tube that is easy to change the height, and then move it up and down the steerer, measuring the height of the horizontal steerer off the table until that height is the same wherever the object is placed. At that point the steerer and table are parallel to each other, and you can take your measurements, adding for steerer centerline and subtracting for the dropout.
This method also avoids trying to get a 2 foot level to remain firmly in contact with 6 inches of steerer.
Yes, I can see your point, although I suspect the method is still sufficiently accurate. Yes, one could accomplish the goal of parallel by measuring, although multiple measurements introduce error as well. Also, one could simply take whatever position the bubble takes on the table and try for the same position on the fork column. I did suggest a 9" level. As I already noted your method seems effective, and it has the benefit of not having to clamp the fork, as others have suggested.