you can contact this guy, simon Vallance, he has a workshop in sai kung and they usually do bike rides on weekends or holidays all over hk, he has a really good collection of old motorbikes as well.
email: simon@simonsworkshop.com
i figured the OP put (road) that he was asking about motorcycles, if i misread it then please ignore my previous post, my previous reply is for motorbikes.
Check out Sonic triathlon, and I think there's Dragon's Triathlon in HK too... they both do road rides... otherwise there is a critical mass meeting every now and then, but I'm not sure if it reaches the critical mass...
do a search on these forums, there are a few threads like this, where myself and others (with more knowledge than me) have posted some good links... from memory..
