<P> To prevent water and dirt from damaging the suspension, gaiters have been used to cover the fork's stanchions . However even when properly sealing the stanchions and sliders, the gaiters have to have small openings in them to allow air to move in and out of the cavity between gaiter and stanchion as the fork moves through its travel . Some water and grit may find its way in through these holes, staying trapped inside and accumulating over time . Since modern dust wipers and seals keep out water and dirt adequately enough by themselves, and since gaiter-less stanchions are generally regarded as more aesthetically pleasing, gaiters have fallen out of favor . </P> <P> Bicycles with rear suspension typically also have front suspension . Recumbent bicycles with suspension are an exception and often employ rear - only suspension . </P> <P> Mountain bike suspension technology has made great advances since first appearing in the early 1990s . Early full suspension frames were heavy and tended to bounce up and down while a rider pedaled . This movement was called pedal bob, kickback, or monkey motion and took power out of a rider's pedal stroke--especially during climbs up steep hills . Input from hard braking efforts also negatively affected early full suspension designs . When a rider hit the brakes, these early suspensions compressed into their travel and lost some of their ability to absorb bumps . This happened in situations where the rear suspension was needed most . When braking efforts cause the suspension to compress it is referred to as brake squat, when braking causes the suspension to extend it is called brake jack . </P> <P> Problems with pedal bob and brake jack began to be controlled in the early 1990s . One of the first successful full suspension bikes was designed by Mert Lawwill, a former motorcycle champion . His bike, the Gary Fisher RS - 1, was released in 1992 . Its rear suspension adapted the A-arm suspension design from sports car racing, and was the first four - bar linkage in mountain biking . This design reduced the twin problems of unwanted braking and pedaling input to the rear wheel, but the design wasn't flawless . Problems remained with suspension action under acceleration, and the RS - 1 couldn't use traditional cantilever brakes since the rear axle, and thus rim, moved in relation to the chainstays and seatstays . A lightweight, powerful disc brake wasn't developed until the mid-1990s, and the disc brake used on the RS - 1 was its downfall . </P>

When was the first full suspension mountain bike made