:icon_couch:

I made my own for about $10
http://i25.photobucket.com/albums/c5..._2360Small.jpg
had the same problem with the 21 inch 90 series tires.
I cut the weld on the V ramps for the tires and increased the angle slightly to get the tire to hit father up on the V ramp. I raised it about 1/2 inch which is a very slight increase.
Works like a charm now.
When you put your front tire in the V ramp at the bottom for the tire for it to rotate froward to lock the tire into position look and see how much the tire is raised from the bottom. If it is close to the bottom increase the angle upward slightly. This will put more pressure on the ramp, the pressure is what locks the front tire into place. When the v ramp rotates froward on the hinge and the tire hits the stop all the weight of the bike is forced forward holding it in place. If the tire is not up far enough on the v ramp it can not have all the pressure available,
Hope this makes sense.
If you ever make one your self you will see and understand what I am saying.
Oh, it was a easy job.
I borrowed a condor and copied it.
The only problem I had was it wanted to slide forward at first. The condor has rubber legs to eliminate that. I made my own with pure rubber silicon