Agnieszka,

In Sketchup:
1 - Draw a tight selection box around the bike
2 - Use CTRL-C to copy it
3 - Open a new instance of Sketchup and copy the bike into it using CTRL-V
4 - Export the bike as a 3D model.

In SH3D:
1 - Import the bike in the usual manner. You will have to wait a long time. It should display correctly now.

NOTE:
In general it's a bad idea to use 5 MB models in SH3D because they slow the program down considerably. If you need a bike as "decoration", there are many much smaller models to choose from.

Hans