loughor hit most of the trails worth riding, Lamma is also pretty good sometimes.
If you do Chi Ma Wan trail on Lantau you can hire from Jacky @ Friendly Bikeshop in Mui Wo. And assorted family members can hang out in MW or on the beach at Pui O whilst you ride 🙂
Lots of places to find Shiny Bits:
Skyblue Bikes – 4 Bonham Strand West, Sheung Wan
Gravity Research – 43 Tai Nan St, Sham Shui Po
Flying Ball – 680 Cheung Sha Wan Road, Lai King/Cheung Sha Wan
Probike TST – 33-35 Chatham Road South, Tsim Sha Tsui
MTBiker – 47-49, Kwong Fuk Square, Tai Po – or maybe round the corner
http://www.hkmba.org has good info also
best time of the year to ride in HK! 😀