Having worked a jillion murdercycle accidents over the years, assuming you are talking a solo vehicle crash, you will see lots of road rash, which hurts like the blazes, 'specially when they take the scrub brush to it in the ER, but won't kill you, and neck/head injuries. I would worry most about airway and C-spine precautions. If it is the left turn right of way type crash, where a car made a left turn right in front of the cycle, head/neck/internal. All of which can not be fixed in the field. I would insure an airway, immobilize as best you can (that will include other "helpers" from jumping in and doing damage), stop any major bleeds (lots of 4x4's), and wait for help. If this happens to be on a busy highway, hope for an ER dr, nurse, or paramagic to stop, then know what they are doing. If a procologist stops to help, don't let him, he has probably forgotten any emergency stuff years ago...