I believe that Todd is incorrect when he suggests that motorcycles do not have a transmission. All motorcycles have a transmission which allows you to change gears. read more
Most motorcycles don't need to go in reverse. They have a tight turning radius or are light enough that they can be pushed into the correct location to then move forward. For those that are too large to push (examples: Honda Goldwing, BMW K1200 LT, bike with a sidecar), these bikes actually do have a reverse. read more
Some motorcycles actually do have a reverse gear. My dad has a BMW K1200LT cruiser that has one. I think for heavier bikes like cruisers it can come. read more