i find its better if the girl understands you will never get rid of the bike but doesnt understand or enjoy anything to do with motorcycles. that way in my case theres a sweet loving kind and affectionate dan and a mean nasty swearing drinking bastard dan that farts and burps. and i keep the first dan for my bike cause its my baby and the girlfriend can deal with the second one 
**edited for craptastic spelling***

**edited for craptastic spelling***
Regards
Dan
Dan