Lolasmiles you say you loathe the term but then seem to defend using it when someone else is talking about their sex lives.
However, you can't joke about having to leave because you've shagged all the men in the small town (very different to running out of men to shag) and then complain and get arsey when the similar sentiment of small town attitudes is said back as "town bike" by someone you've decided is clearly a good enough friend to be comfortable making those jokes
I don't think it's a term that should ever be used full stop. If I said I'd had a lot of sex as a teen, I don't think that gives you the right to call me a town bike full-stop, even if you're a friend. One, because it's different to talk about oneself in a deprecating manner, but another for someone else to join in. But also because one is talking about behaviour and the other is labelling it in a nasty, misogynistic way. And I think women should just stop doing it. Defending it in any way is just as bad as doing it in the first place. And I wouldn't defend the OP for using the term bitch, because it's another misogynistic term.
Until we stop using these words to describe each other we won't change the double standards in society because words contribute to that.
Think how many words are used for a woman who has sex with lots of men: skank, slut, tart, town bike, floozy, harlot, tramp, trollop, loose woman, slag, slapper. I think the only ones for men are player - which doesn't have the same connotations and can be complimentary - or sleaze - which to me implies not just you have sex with lots of women but you're always hitting on unwilling participants - so again it's not just about having sex with women.
Just don't get why you're so keen to defend anyone using it in any situation. And it's separate to why the OP shouldn't have been talking about her sex life.