I am trying to remember an old pc game. you played as a guy on a bike in space.?

[Ben]

You had to do games like measure and weigh things and end up earning crystals to go to the next level and get to a castle and get stupid prizes. you could also buy space bux i think they were called and catch these stars in a net then do maths to keep them. and there was a rainbow that you ride on and it makes you go fast. please help I have looked evrywhere