Did you put a block under the front wheel? The bike needs to be level when you do the plumb bob thing.
something I do to make this an easier check. I run the plumb bob up from the pedal spindle inside the crank arm, then I mark a piece of tape I place on the top tube. It a lot easier to check when you are doing this by yourself. Once you are close you can recheck with the bob to get a real accurate reading.
Last edited by ls01; 08-29-12 at 07:13 PM.