Proof weight goes straight to your behind? The mass there is stretching the space-time continuum so that the longest one centimetre in the world is that one centimetre too far you put your seat up.
Your taint is screaming for mercy, your pedal stroke is as efficient as a burger-flipper on Oxycontin, and if that truck pulls left you will turn to strawberry jam, because you damn sure can't reach them brakes.
BONUS TIP: At that altitude, air is thin, and you may have a vision of the vast Allen key forest. Climb down.