Rear racks are mostly popular among touring cyclists, since they can be used to store quantities of gear in the low over the rear wheel, side to side.  These types of bike racks provide rigid frameworks that hold the bike bags out away from your legs and the moving parts of the bicycle.
Front Racks are similar to rear racks in that they also provide a framework upon which the bike bags could be hung.  Front racks are less popular than rear racks since they add weight to the bike’s front wheel which could hinder steering and bike control.  Front racks are popularly used on tours that require additional amounts of storage space.
Unlike rear racks, front racks can be found in two different styles:  the standard type, whose function is similar to that of rear racks; and the ‘low riders’, which allows one to mount bike bags lower on the front wheel.  The benefit of a standard front rack is that it offers storage space up on top of the bike rack as well as on its sides.  The low-rider style, which does not come with a top shelf, has the additional benefit of stability and control.  In fact, this type of low-rider bikes can help increase the overall stability of the bike by allowing the rider to spread out his equipment load by countering the weight on the rear rack.

QUICK TIPS ON HOW TO USE BIKE RACKS
When loading:

• Approach bike rack from curbside.
• Face bike rack and pull handle up.
• Pull the bike rack down until it’s horizontal.
• Lift your bike into the outside bike slot* (unless it’s already filled), fitting wheels into the slots labeled for front and rear wheels.
• Pull spring-loaded “Support Arm” (it’s labeled) over the bike’s front tire.

When unloading:

• Approach bike rack from curbside.
• Release “Support Arm”.
• Remove bike from bike rack.
• Fold bike rack up by releasing “Rack Lock”.

* Always load your bike into the outside bike rack unless it is already filled.

LOADING & UNLOADING BIKES ON METRO BUSES
One of the good things about loading and unloading bikes on the bike racks is its convenience, plus there's no extra cost for bringing your bike.

The bike rack is attached to the front of the bus and can hold two bicycles. The bikes would not be subject to damages since the bikes in the bike rack don't touch each other, the bus, or other vehicles.

Each bike thus loaded onto the bike rack in front of the bus, can be loaded and unloaded independently.  One does not need to move one bike to reach the other and the bike rack holds most wheel and frame sizes, including children's bikes.

Loading or unloading of bikes may be done at bus stops, except at the times specifically prohibited by the local authorities.  In order to reduce the risk of too many cyclists passing between buses in heavy traffic areas, loading and unloading of bikes are restricted to the first and last ride free stop of any route.

The weight limit for a bike rack that can be accommodated in a metro bus is 55 lbs. per loadable position.  Bikes powered by gas are restricted from being loaded on the bike racks, along with bicycles with non-spoked (disk or solid) wheels.   However, bicycles having electric motors are permitted to be loaded onto the bike racks.

Guidelines when loading a bike into a bus:

1. Your bicycle should be ready for loading as the bus approaches
2. It is better to speak with the driver of the bus and get his consent prior to loading
3. In order to prevent things falling off when the bus is moving, all bike accessories should be removed
4. The folded bike rack could be released by squeezing the rack handle and lowering the rack
5. Your bike could now be lifted onto the bike rack, fitting its wheels into the allocated slots.  The bike could be loaded into the outside slot if it is vacant
6. The support arm over the front tire could now be raised and release, ensuring that the support arm is resting on the tire and not on the fender
7. Bike owners should sit near the front of the bus and keep an eye on their bike

 Guidelines for unloading a bike from a bus:

1. First the support arm should be raised off the tire, and then moved down and out of your way
2. The bike can now be lifted off the bike rack
3. If there are no other bikes on the bike rack, the bike rack should be returned to its folded position

Securing your bike on a public bike rack
Although there aren’t any sure ways of preventing bike thefts, the following tips could help in keeping your bike safe and secure:
1.  Even if your bike would be unattended for only a short period of time, you should always take the time to lock your bike.  Locking your bike is imperative!

2.  It should be kept in mind that a considerable number of bike thefts happen at home premises.  So, one should not assume that a bike on the home premises is safe.  Even if the bike is stored in your garage or somewhere else on your property, it should be kept locked when unattended.

3.  If you are leaving your bike in a public bike rack, the better choice would be to put it in a place that's well lit and busy with pedestrians. Although abandoned "hiding areas" may seem attractive for storing bikes, this seclusion would allow thieves a better chance at taking the bike without any witnesses.  Many thieves will more likely keep away from a bike that's kept in a highly visible area as they are more likely to get caught. 

4.  At every possible instance, lock your bike on a bike rack that is permanently attached to the ground.  This would prevent the thief from removing the bike rack to get the bike.  If an anchored bike rack is not available on the premises, the bike should be locked to a post that is permanently anchored to the ground.  One must ensure that this post is tall enough to prevent the bike from being lifted over the post.  Avoid locking your bike to something that can easily be cut with regular tools.

5.  Make sure that you lock both your wheels and the frame of the bike to the bike rack before leaving.  If the bike rack does not allow for both wheels to be locked, you should lock the rear wheel since in most cases; the rear wheel is considerably stronger than the front wheel.

6.  A tempered steel "U" (or "D") shaped lock should be used for more secure locking.  With other types of cheaper locks, thieves can easily break open with simple standard tools such as a car jack.  The locking mechanism should be on the center of the crossbar for the best securing position.  The "U" lock should also be just big enough to lock the bike securely to a sturdy bike rack.  If one opts for a more flexible lock type, one could obtain chain and cable locks that are available.  Nonetheless, remember that these are less secure than the "U" locks.  When using chain locks, ensure that they are at least 3/8 inches thick to avoid easy cutting of the metal.  A chain with a plastic top coat can also avoid scratching on the bike.