We've got a 100+ year old house, plaster/lath, rough cut 2x4, not always evenly spaced, with occasional surprises (like hidden doors where a previous owner just plastered over a doorway). Those tension poles don't always work well, sometimes the plaster cracks and the lath gives way.
Either on this site or another one someone used garage door rails hung along the ceiling with roller'd hooks to hang the bikes from. I believe someone sells the setup through one of the local bike shops here. Depending upon how wide your space is you might be able to suspend a beam across the room supported by 2D tripods against each side wall. Then you could use the roller track system or just screw hooks into the beam.
Too many variables to do remotely, and too far away to do locally, so you'll have to use your imagination.
Go to a local dry cleaners and look at their floating hangers to get some ideas.
Or just get some ladders and rest a pole across them and rack the bikes by their saddle noses like is seen at triathlon events. Totally portable, no holes, and instead of having all the bikes on the back wall you could have them racked in front of the left and right walls with an aisle down the middle. Keepers to the left, transient flippers to the right.
Sorry in advance if this post just adds confusion.
Last edited by treebound; 05-23-11 at 12:41 PM.
Reason: Monday eye'd typos