I studied for my Psychology degree a LONG while back... It's one of the few subjects (aside from medicine) where sex is a perfectly legitimate subject for study. One thing I learned (and was surprised by) is that women divide into three basic groups, comprising roughly 10%, 30% and 60%. The second group - 30% - are "as depicted in conventional pornography". That is, if you insert a big enough penis (or acceptable substitute), and jiggle it around long enough, she'll orgasm. The largest group - 60% - only orgasm as a result of direct clitoral stimulation. And the third group - 10% - don't orgasm regardless of what's stimulated or how. So much for the figures... which are perfectly legit, and have been known (and largely undisputed) since the late 1960's. Physiologically, it seems that there's a perfectly simple reason: inserting a penis into the vagina and moving it back and forth puts strain on the labia minora ("inner lips") which in turn drags the clitoral "hood" back and forth over the erect clitoris. If the opening of the vagina is more than an inch away from the clit'... then there's simply not enough stress applied to stimulate the clitoris sufficiently. I'm intrigued. From personal observation, the above seem to be true... but the geometry of women's crotches covers a FAR wider range than the range displayed by we males. (Despite rumours to the contrary, the standard deviation for penile size is remarkably small. That is... the vast majority of blokes have penises that are basically the same size and shape. A Foot long penis is a statistical rarity) There seems, by contrast, a HUGE range in the size and relative proportions of women's parts: some have hardly any inner lips at all, some have ones so massive that they protrude markedly. some have labia Majora ("Outer Lips") that are prominent enough to form a ridge, others have no ridge at all. SO, a straw poll. Does the "an inch or less" rule apply from YOUR experience?