Suggestions for outdoor commercial (security/parking) stands I'm looking for suggestions for space efficient stands for parking multiple bikes. 

A sports club (not cycling) for which I sit on the committee is looking to solve a bit of a problem. At the moment many people come to train in the evenings/weekend by bike and end up piling them up in one of the gym rooms. This has been mostly fine because it's dry, relatively secure and they aren't really in the way. The numbers are increasing, though, and ''something has to be done''. 

So we're on the search for some stands. We have an amount of outside space that can host some racks, but we want to buy something that can maximise the numbers held, while hopefully still allowing random access (i.e. any bike can be taken away at any time by its owner). 

The current suggestion is http://www.esedirect.co.uk/p-2246-the-s-stand-bike-rack.aspx - we've space for about five of these style (i.e. ten bikes). 

I feel sure that we must be able to fit more bikes into the space. 

So without knowing the dimensions within which we must work, I'm looking for a few candidate types of solutions which are particularly space efficient. 

Edit

The main problem I think with these 'S' stands that have been proposed is that, when placed against a wall, I think that the asymmetric nature will mean that, when busy, the slot facing the wall is likely to not be used. 

I must admit that my initial reaction is that you have to argue as to why to not just get the Sheffield stand. The wall mounted option looks like an interesting idea and that was certainly the kind of response I was hoping to get!
It is hard to beat a “Sheffield” stand, as they make it easy to lock the bike and don’t bend your wheels if the bike is knocked over.



Cambridge Cycling Campaign did a good write up on the options.