+2  A: 

Since Slices.WheelId is an FK, you cannot expose it in your client model, period. There are ways to get the value, though.

var wheelId = someSlice.Wheels.ID;

Update In EF 4 you can do this by using FK Associations instead of independent associations.

Craig Stuntz
A: 

So how can I set the value of that column when I create a new slices record if it's not mapped? That's ridiculous.

A: 

Try to remove foreign property column from Entity set using entity model design it will solve your problem

For example

We have two tables one is customer and other one is order, using entity model design we added association between customers and orders when we do this Ado.net entity framework i will add navigation properties to both below tables.

Like Customer.Orders - Here order is list Order.Customer

One - Many relation.

So we need to remove property from with name CustomerId[Foreign key column] from Order entity set.

For reference:

http://social.msdn.microsoft.com/forums/en-US/adodotnetentityframework/thread/2823634f-9dd1-4547-93b5-17bb8a882ac2/

Venkat