This may be way off,, but for the longest time I have seen only younger girls on the crotch rockets and hardly ever do you see them on the back of cruisers? Plus on top of that,, riding the crotch rockets and them being the fastest,, you see the girls with the least amount of protective gear on,, if they are even wearing any gear. Mostly they are riding with a mid-driff T-shirt on and a pair of low cut jeans.
I will have to admit I like the looks of it but it seems to be a phenomenom down here,, or at least in Georgia and Florida.