10 bicycles.
Explanation:: All the cycles will have at least 2 wheels, so 16 cycles will have 16x2=32 wheels. But in total there are 38 wheels. So the extra wheels (38-32=6) must be of the tricycles because bicycles have 2 wheels and tricycles have 3 wheels.
Therefore, the number of tricycles parked is 6 and hence the number of bicycles is 10.