"greater trochanter to the ground when standing erect in cycling shoes. "
In realistic terms I’d think this method is easily open to inaccuracy due to the difficulty of palpating an accurate greater trochanter head on many people.
Yeah, but I think the greater trochanter is easier to palpate and measure to than the other bony protuberances that have been used (i.e., the symphysis pubis and the ishcial tuberiosity). Besides, I don’t think that tremendous accuracy is all that important, i.e., as I see it the point of performing such measurements is just to assure that your saddle height falls w/in a reasonable range (which many here do not). After that, it should be “set it and forget it*”.
*Recognizing, of course, that you should keep a record of the measurement, and mark your saddle height on your bike using, e.g., a piece of tape.