I'm guessing you've tilted the frame so far to get the BB drop to a reasonable 45mm, but combining that with enough fork offset to provide a safe clearance between tyre and down tube seems to have left you with a perilously small amount of trail. Read very thoroughly on the subject of steering geometry before committing to metal. Also look at Wiggins' madison bike - it's basically a small bike with the bars and saddle cantilevered a long way off the frame.
I'm guessing you've tilted the frame so far to get the BB drop to a reasonable 45mm, but combining that with enough fork offset to provide a safe clearance between tyre and down tube seems to have left you with a perilously small amount of trail. Read very thoroughly on the subject of steering geometry before committing to metal. Also look at Wiggins' madison bike - it's basically a small bike with the bars and saddle cantilevered a long way off the frame.
1 Attachment