Originally Posted by
Hondo6
A 13/16" seat post should be 0.8125" or 20.6375 mm in diameter. If it's measuring 20.72mm, then it's around 0.1mm oversized - not undersized - IF that measurement is accurate.
I was going off the millimeter specs on Sheldon's site, rather than actually doing the math:
BMX bikes Better models
22.2 .875" (7/8") BMX bikes Cheap models
21.15 .833" (nominally 13/16")