We have an Olympia 22 that we use as a carry-on sometimes. If you stuff it as full as you can possibly get it then, yes, you are going to have trouble fitting it into the overhead, and the airline may force you to check it. If you do not over-pack, though, it will fit fine.

Its basic dimensions are 22x12x12. The 22x12 part is fine. it is when you stuff it all the way to 12" deep that you start to have problems. If you can compact the depth down to 7 or 8 inches you will absolutely not have a problem. At 9-10 inches it gets to be a squeeze. Beyond that is when you might have a problem.

Good luck.