There is some info on the Ride Thailand site about some upcoming bike events in the area.
"Welcome To Thailand Northern Bike Week 2005 / 8 th December LAMPANG BIKE NIGHT 2005 / 9 th December CHIANG RAI BIKE PARTY / 10 th December CHIANG MAI BIKE WE
"Welcome To Thailand Northern Bike Week 2005 / 8 th December LAMPANG BIKE NIGHT 2005 / 9 th December CHIANG RAI BIKE PARTY / 10 th December CHIANG MAI BIKE WE