I think I have come up with a good way to join the bicycle rims to form a geodesic dome.
Bike rim domes are a thing, and they are usually held together with zip ties.
Zip ties are subject to weathering, and not necessarily very strong.
Bicycle rims vary in width and radius.
I would eventually like to weld together any bicycle rim dome I build, but even then, positioning will be an issue.
After musing on it I came up this joint:
PVC pipe bicycle dome joint side view 
PVC pipe bicycle dome joint top down 
I grabbed two different sized rims, to see if the joint would work that way, and it does.
That option would mostly be used between courses or layers.
Each layer upward might use a smaller diameter rim.
The zip ties could/should be replaced with wire binding, or even a temporary bungie cord.
Maybe hose clamps?
The pipe could be steel, but more importantly the pipe and rim together make up a measurement that can be used to lay out the dome.
If for example we planed for 10 rims as the base of our dome, and one rim plus the pipe joint measured 24", we could lay out 38.833 inch (3.23608333 foot) radius circle, and drive rebar stakes every 24" along the ~ 20 foot circumference.
Each pipe joint can be slid over the rebar post to achieve a very clean layout.
Pipe size can be increased or decreased to help a given rim size fit a needed circle diameter.
Once proper positioning is achieved strengthen the joint by driving screws through the empty spoke holes into the pipe joint.
If you are using wheels with the spokes intact, try self tapping screws.
The pipes could also be dowls or properly sized branches.
Any large enough durable cylinder that can take screw should work.
I can see using tin cans ,if you didn't need the dome to be strong, or if you filled the joint with cement after it was screwed together.
If the pipe is small enough in diameter (so the rims touch each other )or they are made of metal, welding becomes an option.
I don't weld(yet) so I'm designing this dome with that in mind.
To ease everything from covering the dome to driving screws in the joints, a rim without spokes might be best.
On the other hand, spokes and a hub ad strength and would prevent a tarp from pooling.
Splitting the difference and cutting the spokes off of one side of the hub might be the way to go.
5
