Disclaimer: Please understand this this is a figment of my imagination, set in the Red Faction theme. It has absolutely no bearing on the game (Even though the game really should have included motorbikes).
Bikes are cool and all, but to me, the Trike has a special appeal.
This is probably the best overall view of it.
As you can see, I managed to wedge a gas tank under the rear fender.
I don't know the game very well, so I can't say it's accurate. I'm sure it's pretty close, though. Again, this is probably a long shot, but does it roll? (Expect to be seeing,"does it roll?" on more of your creations.)