Character rotation is resetting

Hello all,

I'm working on a bicycle race game where you can ride free, and at certain points you can start a race. When a user wants to start a race i want to position the bike to the start point of a race.

I do this with the following lines of code:

 var startposition : Vector3;
 var startdirection : Vector3;
 
 startposition = Vector3(10,10,10);
 startdirection = Vector3(0,90,0);

 // when start button pushed:
 gameObject.Find("Bike").transform.position = startposition;
 gameObject.Find("Bike").transform.eulerAngles = startdirection;    

For the position this is working fine. The rotation is a little of a problem: For like 3 or 4 frames it sets the direction correct, however after that few frames it changes it´s direction to the previous direction.

Any ideas how to fix this? Thanks in advance.