O.K., heres my thoughts on the matter of vertical and/or horizontal velocity.  Yes, it is true that bender will accelerate at a rate of 9.8 m/s/s downward, however velocity is a measure of speed AND direction, and since bender will be traveling along a somewhat horizontal plane before going off the cliff so his SPEED will be the initial velocity + the acceleration of 9.8 m/s/s, or 53.whatever mph + his takeoff speed which could range between 25 mph depending on his in-run.
HOWEVER, none of this takes into effect the wind resistance of a person and a bike.  Judging by personal experiance i would ESTIMATE, (this is purely a hypothetical guess) that his speed would decrease by a good 5 mph while in the air, however brief the period will be.
After all this thought, i would put bender's speed at about 55 mph when he does in fact hit the ground, which would undoubtedly cause massive damage to him and whatever bike he may be riding.
And P.S. to all of you who think that a bullet fired from a gun would hit the ground the same time a bullet dropped from the same height would, you are WRONG.  even if both were shot/dropped on a LEVEL surface miles and miles long, the fired bullet would hit later.  Why?  because after leaving the muzzle of a firearm, a bullet will accually rise a slight bit and then drop in a parabolic sort of manner.  If you don't believe use a laser to boresight a gun then fire the same gun at a target 100 yards away.  If it is a medium caliber rifle such as a .308, 30-30, 30.06, or 270 the target will show that the bullet rises approximetly 1"  (of course this will vary based on powder charge, caliber, and bullet grain weight)but the pricipal is the same.