No Suspension Mountain Bikes - Mountain Bike Zen
Do I Need A Bike With Suspension?
Although the very first mountain bikes were built with no suspension, mountain bikes with no suspension are now quite rare. It is far more common for track or road bicycles to have no suspension at all. It is generally advantageous to have no suspension if you are riding on smooth surfaces such as an indoor track, velodrome, or outdoors on smooth roads or paths. Suspension is there to soak up the lumps and bumps but it will also remove some of the efficiency of the cyclist efforts to transmit his leg power into forward motion by soaking up some of the kinetic energy. In addition it will generally mean that the bike is heavier.
If you are sure you will be riding consistently on flat smooth surfaces with lumps and bumps and absolute rarity then a rigid bike without suspension may be fine for you. If unsure whether you need suspension it is may be possible to start riding a rigid bike and add a front suspension fork later on but it is worth checking the measurements of your steerer tube against the suspension forks that are currently available as often making this sort of upgrade just isn't a realistic option.
A classic rigid bike fork...
All but the basic entry level suspension bikes will also feature a lockout which enables you to turn the suspension off, usually this still allows a very small amount of movement, but effectively this is to turn the bike into a rigid bike, particularly useful for long steep climbs. Of course if your bike only has front suspension and it seizes you will have a rigid bike on your hands.