In the distance between the bearing wall and the outside wall.
It sounds like you have a 15 foot span from the bearing wall to the foundation walls. I would put cross bracing 5 feet from the bearing wall and 5 feet from the outside foundation wall. This will give you about 5 feet between them as well.
So, if I understand you right, you will then have to put the cross bracing in 4 places for the span.
Good Luck!
Dodgeman
PS - I almost missed your post, as the start of this thread is now several days old. If you have any additional questions/comments, please start a new thread at the top. - Thanks.