Originally Posted by
Elvo
1. Establish horizontal control using a digital level making sure your handlebars are level to 3 significant digits
2. Find out the mid point of your stem to 3 significant digits
3. Hang a surveying plumb bob from the midpoint of your stem
4. Adjust stem as needed until plumb bob is centered over the mid point of your rim to 3 significant digits.
Hang the bike by the front wheel from a hook.
Put a level across the bars.
Adjust until level.
The bicycle is the plumb.