I haven't tried this on O3D but have successfully used bike mounts on Optimus P500 and Motorola Defy (really good to use for both navigation and sports apps).
I did purchase one of those universal bike mounts, and it was TERRIBLE. So instead I got a hold of an original LG car mount. The piece itself which holds the phone snaps off from from the rest of the mount.
From the universal mount I pretty much just cut off anything but the piece which mounts the handle bar. I then melted the the plastic from both the original "snap on" piece and the universal mount, pressed them together, and then separated them. They now had a good fit, so I super glued the pieces together and man! the result is beyond what I could've hoped for.
It's very durable, doesn't take up a ton of space (unlike the universal monsters of mounts).
When I "melted" the pieces together I ensured to also include the slide on mechanism to release the mount. Therefore I can now get the O3D original car holder and just snap it on to my bike.
In order to do this, you will have to take a risk... but it was clearly worth it for me. I've used it a lot, both off road and on road.
I'll send a pic of it if you want.