Posting again because I accidentally answered it instead of just commenting…
I don’t remember the plot exactly, but the main character was a boy, he lived with his father, who (I think) was a scientist, and I remember two scenes:
He rode a bike in an awesome way, through every kind of ground – especially rugged, with dirt and mud;
He read a book with his lizard (which lived in a kind of terrarium behind his bed) on his shoulder.
I think it was an adventure, live-action movie. I watched it on TV when I was a child, and I think I didn’t see it entirely.
Perhaps the villain was a woman and she had something to do with the boy’s father