Jeff, you read my mind. Trail and error is my piece of cake.
Although i hoped for a more sophisticated answer, i can live with yrs.
After i jumped a certain ditch several times with first gear. The approach was very narrow, just 4 mtrs, and slippery.(gravel) I thought that, because of the wheelspin, to try it in second one more time, to see if that was any better.
Well, no, i made it to the other side, only my speed was not enough to lift my rearwheel out of the ditch. So i was backwards into the water. Lucky it was only knee deep. Man, 228 pounds is heavy to lift. It was a steep ditch(vertical to say) and 1.2 mtrs deep. Happy jumping everybody.
And Roosterboy, yeah i think weight has got to do with it a lot. Also see above. Splash!!!!!!