whats the degree alex?
i think a cloak room idea would certainly be best, how that would be implemented i dont know (thinking on the side of the contractor). A lorry with a modular racking system, hanging bikes up by thier front wheels, but also allowing the racking to slide?
hanging a bike up on its front wheel is ok, but you need a bit of space to get them up and down, if they were on sliding rails, they could be, once hung up, pushed closer together to save space.
perhaps have a fabric/rubber curtain of some sort inbetween each bike to prevent scratching/damage?
if you designed it well, it could even be unmanned?
like the car park in irobot, and in the VW factory, you enter a number known only to yourself, and it spins the carousel of cars/bikes until yours is at the collection window, and then unlocks the door.
some Orange shops have this for charging phones, instead of having a ticket or a key you can loose, you punch in a number of your choice to lock the unit, and punch in the same number to unlock it.
a phone number being the easiest one, and very secure, 11[??] digits
i think you may have a density problems, bikes dont stack very easily, and owners dont appreciate them being bashed around…