Go to Bissoe and look for the Cafe/Bike shop in the car park (can't miss it). Ride towards Portreath (signposted) and after about 3 miles (bit of track, bit of road, then more track) hang a left for acres and acres of disused open cast mines which are superb for cycling. If you just fancy a fast ride, carry on to Portreath – a pleasant village with a nice beach. About 12ish miles from Bissoe.
A mate of mine runs Revolve Bicycle Works that hires and sorts bikes and based in Devoran slightly further back from Bissoe – if you need any pointers or bike stuff, he's the man.
If you like mad jumps, look for "The Track" near Portreath – a BMX/MTB centre.