The small sized ones are 22.2. I just called those guys and I'll call back tomorrow to find out for sure. The big ones, 25.4 have an OD of about 26.2 on the outer tube side. They don't clamp down very well on the Big Dummy.

I can easily get the 25.4 to work however with shims.

PS: Anyone with a pair of calipers care to give us the two relevant measurements? Big Dummy tubing size and V-rack/Adventure Rack tubing in millimeters?

PPS: Do not get the smaller ones. You cannot do the coin trick on these because they are only threaded on one side.

I got my 25.4 to work with aluminum can shims but it's a PITA.