Repair stand

A few years ago I built a repair stand using instructions from an article in Bicycling Magazine. The base piece of plywood deteriorated and I tried to replace it with a double piece. But the pieces I acquired turn out to be too warped and even though the holes line up, as the bolts screw in they push the pieces flat and the holes no longer line up.

I could get new plywood. What I would prefer to do is attach the base plate to the concrete patio outside. When I'm done using it I can just unscrew the stand and store it in the shed, so it doesn't rust permanently to the base plate. The base plate is flat and unobtrusive and hardly anyone will notice it's there.

Another option is to attach it to the brick wall, and screw the "arm" piece of pipe into that. Again removing it when I'm done will keep it from rusting permanently onto the base plate.

My problem is I don't know how to attach things to concrete or to brick walls. It's an old house, built in the 50's probably, so the concrete might be a better choice than the brick. Does anyone have experience attaching things to concrete?

I've never done it, but just remember that the ordinary way of attaching things to concrete is to set threaded rods into the concrete and put a nut on top of whatever you're bolting down. Since you want it to be removable and not have the ends of the rods sticking up for people to trip over, you're going to need to set threaded sleeves into the concrete and use bolts on top.