Feel around for your hip JOINT below the tissue of your IT band. It helps to sway side to side. Place the measuring tape there and stretch it down the outside of your leg to your knee joint. That's your femur length.
I have a 36" inseam and 19" femur. I ride in an 18" passier grand Gilbert and a 17.5" collegiate nobility.
they just mean how long their thigh is. It's quite difficult, perhaps impossible, to accurately measure the length of a femur without cutting someone up.
using the height of the head as the unit of measurement, most people are around 7.5 heads tall, and if you stand flat barefoot, you should measure 2 heads from the ground to the knees, and then 2 heads from the knees to the place where the leg bone hooks into the hip, about mid-way up your pelvis, slightly above your crotch. If you're taller above the knees than below the knees, you have a relatively long thigh.
here's a diagram of normal human proportions: http://www.google.com/imgres?imgurl=...QEwBw&dur=1991
Manut Bol (the man in the photos) had a heart to match his incredible size. After he retired from the NBA, he spent a lot of time and most of the money he made playing basketball on building schools and other humanitarian efforts in his native Sudan. He died from a rare skin disease because he delayed his return to the US for medical treatment to campaign for free elections in Sudan.
Would that all professional athletes gave as much to humankind as he did.
__________________________ "... if you think i'm MAD, today, of all days,
the best day in ten years,
you are SORELY MISTAKEN, MY LITTLE ANCHOVY."