The Road Morph didn't fit my bike (small with very sloped tube) either, and I tried EVERYTHING (except the on-top-of-the-top-tube solution I just read about), following advice from fellow TEers. So I carry CO2 on short rides or group rides or with the boyfriend (he has a pump on his frame) and on very long rides when I'll be by myself on long stretches of road with little or no civilization, I carry the Morph in the back pocket of my jersey (which, surprisingly, is less uncomfortable than you would think).

When I come back home (I'm currently at the foot of the Alps!!) I'll try the over-the-top solution... Hum.