How to implement LOD in Unity

I know the concept of LOD, but my question is how can it be used in Unity. I don’t think that there’s a kind of LOD manager in Unity, so do I have to manually code it? I looked up the manual and the website but could get the exact answer.

Example, if there a high poly motorbike and I have 3 LOD models of it, then should I code something like :

if(playerdistance >50)
    show lowest detail model
else if (player distance between 2 and 50)
    show medium detail model
else
    show high detail model

This seems to me a logically correct approach. I have managed to get the results that I want this way, but I just want to know whether it can be improvised and the same thing can be achieved in a better manner.

Thanks for reading!

You can read more about LOD here: Unity - Manual: Level of Detail (LOD) for meshes

There is a LOD manager, in Unity 3.5. So use that.

use this link for more details