art of the thrill of riding off-road is dealing with sudden changes in terrain. Loose, soft surfaces such as sand, snow, mud, loose gravel, and rocky scree are among the hardest and most challenging to ride. Climbing, braking, and descending on these surfaces requires a positive approach, a properly set-up bike, and the use of a few simple but effective techniques. Assume that everything is rideable until proven otherwise. The key to surviving any loose surface is to maintain momentum and traction by keeping the back wheel turning. If it is a long section of soft ground make sure that tyre pressures are low
ROCK RIDING
On loose rocky surfaces (right) the front wheel is easily deflected and can jump disastrously if it is not controlled well. Try to avoid turning the bars to steer. Instead shift your body, especially your
shoulders, to incline the bike to the direction you want to travel.
SNOW PROBLEM
Riding in snow (below) is a challenge. It is like riding in sand, except you tend to sink deeper and further. Even keeping the bike in a straight line requires a constant series of corrections as you try to manoeuvre from firm spot to firm spot.
SAND RIDING: DOWNHILL Don't always expect to be able to free- wheel downhill. You will find soft sand (above) increases rolling resistance, and often it is necessary to pedal on descents to keep going. Remember to keep the tyre
pressure low to prevent digging in.
TYRES
The differences between the bulk of mountain-bike tyres is no wider than the average tread, with just a few basic types and the sizes that count. The most common size is 26 x 2.125 in, but tyres are available in widths from 1.0 to 2.6 in. The three basic types of tread are slicks, knobblies, and multi-purpose. The completely bald slicks bring a mountain bike as close to a road bike as possible, knobblies are for off-road riding, and multi-purpose are for road and off-road.
SLICK
The Matrix Road Warrior (left)
is a trendless slick tyre for optimal grip on asphalt and concrete. This
helps give a comfortable ride with minimal rolling resistance and low tyre noise.
MULTI-PURPOSE (1)
The Specialized Nimbus (right) is an ultra-lightweight all-around performance tyre that is very stable
in wet weather. If using it off-road
it is suitable for hard-packed surfaces, but hates mud.
MULTI-PURPOSE (2)
The Matrix Cliffhanger (left) is an all-around cross and road tyre.
It is satisfactory on hard-packed
surfaces, but its side lugs are too closely spaced to let mud escape.
KNOBBLY (1)
The Onza Racing Porcupine (right) is the quintessential soft rubber compound knobbly ,with well-spaced, well-bevelled lugs.
Traction is excellent but the life
of the rubber compound is short.
KNOBBLY (2)
A Panaracer Smoke (left) rear tyre is designed to cover all off- road bets. Well-separated lugs
discharge mud easily while the central horizontal bands provide traction to improve acceleration.
KNOBBLY (3)
The Specialised Hardpack (right) is a popular racing tyre whose tread design works well on
rocky terrain. The large 2.2-in
size provides a greater volume of air to ride on and consequently a more comfortable ride off-road.
SOFT SURFACES
enough. On a soft surface fully inflated tyres dig in, creating unnecessary rolling resistance. Lower tyre pressures mean less digging in and more tyre area in contact with the surface to generate greater traction. How far tyre pressures can be lowered is a matter of degree. On a really soft surface, a lightweight rider using a wide tyre can go as low as 20 to 25 psi, whereas a heavier rider on narrow rims might need 30 to 40 psi to avoid a'puncture from the rim pinching. Before reaching a loose surface, change down to a gear which will give you enough traction without spinning out. Pick the straightest line through. Shift your weight back, keep pedalling, and keep the front wheel up so that it lightly skims the surface, preventing it from its natural inclination to dig deep into sand, snow, or mud.
THE WET STUFF
Before entering a stream (below), make sure you can see the bottom. If you can't, don't try it. Before you hit the water, switch to a lower gear, shift your weight back and accelerate so that you have enough speed to carry you through.
WORLD LOCATION: USA 8,800 • GRUNDIG COURSE - - -KAMIKAZE COURSE GONDOLA ... CHAIRLIFTS - - - WOODED AREA • 9,400 ALTITUDE IN FEET
THE MOUNTAIN BIKE
Racing
rom the start, mountain-bike racing has been an informal high-energy sport, unhindered by petty restrictions about bikes and clothing. The first mountain-bike races, the pioneering 1976 Repacks, were impromptu downhill time trials on a fire road that dropped 396 m (1,300 ft) in under 3.2 km (2 miles). Since then this US-invented sport has now spread worldwide, with improved organisation, diverse events, and spectacular courses; but the gritty spirit of mountain-bike racing remains the same: a rider-plus-bike versus the elements and the rest of the field, without mechanical back-up. Race meetings can consist of a cross-
country event, a downhill, a hill-climb, a dual slalom, and observed trials (see p.50) with riders competing according to skill, age, and sex. Internationally recognised ability classes are Pro-Elite, Expert, and Sport. Age groups are Youth 12-15, Junior 16-18, Senior 19-39, Vets 40-49, Masters 50+. Courses vary accordingly. A Senior mass-start cross-country course is from 39 to 58 km (24 to 36 miles), the circuit is at least 6.5 km (4 miles), with 90 per cent off- road and no more than 10 per cent where the bike may have to be carried. Downhill races cover about 8 km (5 miles) and must descend at least 80 per cent of the course.
8,000 ft
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;# 4 RACING MOUNTAIN-BIKE RACINGTHE CYCLO-CROSS CONNECTION
Before mountain-bike racing there was cyclo-cross (left), a gruelling sport used by road racers for mid-winter training, on bikes fitted with narrow off-road tyres and cantilever brakes. Cyclo-cross courses are devised with sections that are faster if the rider dismounts and carries his bike, whereas mountain bikers prefer to ride the impossible. While mountain bikers may not receive mechanical help in a race, cyclo-cross riders can switch bikes. There the differences end. Cross-over between the two sports is common, with several cyclo-cross graduates becoming mountain-bike champions.
A Sport Evolved
Today, mountain-bike racing has branched out to incorporate different styles of racing. Apart from the cross-country races, there are other events. In observed trials, riders compete against the clock and incur penalty points whenever they dab (put a foot down). In dual slalom events, a field of riders compete head-to-head in pairs in sudden death races until all but the last two are eliminated. Races are over a short, downhill course of about half a mile. The hill climb event is a mass start, first-past-the-post race that climbs steeply, with competitors riding up most of the downhill course and barely managing to average 11.3 km/h (7 mph).
THE LEGENDARY RACE COURSE
Mammoth Lakes (left), in California's Sierra Nevada mountains, is at the
forefront of ski resorts that have turned
their facilities over to mountain-bike racing in spring and summer. Mammoth is a legend among off-road racers. The
cross-country course, ridden for the 1991
World Cup series, is a long 19.4-km (12-mile) loop that the racers ride three times. Its dramatic "Kamikaze" downhill trail drops over 610 m (2,000 ft) in
6.3 km (3.9 miles) – the Pro record is 5 minutes, 25 seconds, an average
speed of 69.4 kmph (43 mph)!
PRESTIGIOUS EVENT
The one race that determines the best overall mountain biker is the cross-
country event (right). With the courses
restricted to natural obstacles only, designing them has become an art. Start and finish areas have to be wide enough to allow riders to start en masse, then often narrow quickly to single track. This means that riders often sprint for
position early on, only to find themselves
out of breath as they hit an oxygen- sapping incline.
THE MOUNTAIN BIKE