Spacing Two Tier Bike Storage Racks
When it comes to two-tier bike racks, these typically come as complete units, so you won't have to worry about horizontal or vertical spacing. The unit will usually then need to be placed with 10 to 15 inches of clearance on the side, from a wall, door, or other obstruction, to allow room for handlebars of stored bicycles.
You will then need to factor for aisle space beyond the rack.
This again, should be at least 48 inches. Add this to the length of your two-tier bike rack. This measurement will be the total distance needed in your bike storage area to use the bike rack.
You will also, generally, need 9 feet of clearance measured from the ground to the ceiling or other overhead obstruction, like a ceiling fan or lights, to store bicycles with these racks.