There are a lot places to locate an antenna on a motorcycle.  When locating an antenna, getting the antenna up as high as possible is the most important issue for achieving better range.  All antenna installations must produce low readings of reflected power on a reliable SWR (Standing Wave Ratio) meter.  If the SWR reading is too high, the reflected power could cause the transmitter to fold-back its output power to keep the transmitter finals from destroying themselves.  In older radios the high SWR reading will eventually destroy the transmitter.

Amateur motorcycle antennas most often need some form of ground plane and all of them need a good ground.  In the four pictures shown below, the antennas are mounted on the luggage rack that is attached to the top of the GoldWing trunk.  Both luggage racks are securely grounded to the frame of the motorcycle with a large gauge of wire.  

In the four pictures shown above, the antennas are mounted using a custom built bracket that is built for MARC.  This bracket makes mounting UHF type antennas quick and simple on bikes with the same or similar sized rack bars.

Other mounts can be made form simple CB antenna mounts.  An advantage to using CB antenna mounts is that they are cheap, good looking and will adapt to a broad range of installation needs.  In the pictures listed next, this bike is using CB mirror brackets to mount an antenna on its luggage rack.  Hams using antennas with NMO style mounts, often find that simple mirror brackets work best for their large hole requirements.  In the white GoldWing pictured below, that antenna uses an NMO mount and is using a mirror bracket.

Various types of antennas can be used on a motorcycles.  For ham radio, if the bike is going to need a dual band antenna, MARC has found that the following work well in an environment where there is a lot of vibration:

    *     Comet, HP-62  2-Meter & 70cm (440)

    *     Diamond CR-214S  2-Meter & 1-1/4m (220)

    *     Larson  NMOQ2/70B  2-Meter & 70cm (440)

Antennas that aren't rugged enough don't survive will on a motorcycle.  They often will break leaving the rider without any ability to communicate.   

For a CB installation, there are more versatile options in the types of antennas that are available.  FireStik makes good antennas and even offers a "no-ground plane" design that limits the problems of installing a CB on motorcycles.  No ground plan antennas require the supplied cable length be carefully preserved.  Excess cable can be tucked into various openings on the bike as long as the excess isn't coiled into loops.  Normal CB antennas can work on a motorcycle and give good performance if a ground plane can be established. 

Low band antennas are generally too large for any serious motorcycle installation, however a few people have made some things work.  There isn't much information on low band antennas here.  What is here is what one of our members has done to operate on the low bands with his motorcycle.

It is clear from the picture above, this is a rather large antenna.  As of this writing, it is unclear whether this is working as expected on his motorcycle.  However, this antenna, which is called a "Screwdriver",  is successful in mobile operations and the owner of the motorcycle, who also owns the antenna, has had success using this antenna on the back of his small pickup.

Feed-lines or coax cables for ground plane antennas should be kept reasonably short and as small as possible.  My personal favorite is the Diamond C101 coax assembly.  This Diamond package provides a 6.5' length of RG316 Teflon coated coax and a detachable PL-259 connector assembly.  Having a removable connector assembly allows the installer to work with smaller holes and the small 1/8" thick cable is easy to feed and store.   Regular 1/4" RG58U cable assemblies are less expensive and will work very well if you don't mind the large size of the coax cable.