Hi Slowman,
I just noticed the "X/Y Peer Review" article on the main page:
http://www.slowtwitch.com/...eer_review__150.html
Just a couple of thoughts:
- My proposal for the rewrite of 1.3.023 would most likely require another "2 wire" harp much like the one for the proposed 1.3.013 in order to account for varying BB heights. Lining up with the edge of the frame assumes a 24cm BB height.
- Alternatively, a "3 wire" harp could be used that places the 3rd string 66 cm horizontally away from the first string. That way, one would line up the 3rd string with the center of the BB instead of the vertical member after flipping it around to check the extension. If the 2 chosen angles are the same, then the wires would all be parallel. If the extension angle is different, the angle of the 3rd wire could be changed to give the correct spacing, still using the seat wires as the limit (no matter the angle chosen for the seat).
- The calculation and checking of the allowable extension would be pretty easy once an angle is chosen. For the example of an angle of 78 degrees and an offset of 66cm, the horizontal extension dimension as measured from the BB can be figured out from the difference in the heights of the seat and the BB off of the ground.
- Extension = 0.213 x (SH - BB) + 66cm, where SH is the vertical seat height measured off the ground, and BB is the vertical BB height measured off the ground.
http://bikeblather.blogspot.com/
