Cycle News - Archive Issues - 1970's

Cycle News 1970 12 08

Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles

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New Air Suspension- Available Monotrack Engineering, a fairly new design and manufacturing firm in Costa Mesa, Calif. which specializes in motorcycle components, has· hit the market with an invention that promises to revolutionize motorcycLe roadholding (or dirt-holding, as the case may be). The invention is an air suspension for the rear swinging arm, that replaces the shock absorbers and coil springs of any motorcycle. Long recognized as the ultima te suspension medium, air units have lacked the technology to be practical - up until now, says Daniel E. Hanebrink, of Monotrack E.ngineering. In his book, Motorcycle Engineering, bike designer P.E. Irving points out that "in whatever way it is compressed, air has the property of providing a progressive spring-rate...A normal. parallel-wound helical coil spring has a constant rate; that is to say, if it takes , '100 lb. to compress' it one inch, and so on until it becomes coil-bound. However,· with air the nile rises continuously from the start of compression until it reaches an infinitely high value at the end of the stroke. Furthermore, as air cannot be compressed into no space at all, mechanical bottoming is impossible." Air suspension for motorcycles offers several distinct advantages over conventional,. spring operated shock absorbers. Progressive action is the chief advantage, meaning you don't. get wheel-hop or bottoming: the tire stays in contact with the road surface even over farily substantial bumps. According to Hanebrink, the air suspension absorbs bumps sufficiently to prevent a machine from "launching" and the rear wheel remains in driving contact with the track a greater percentage of the time. One can imagine the seconds per lap that could trim off a racer's time. Sealing and mechanical wear have historically been the Achilles heel of air suspensions, but Monotrack claims. to have brought these problems under control by using materials and techniques designed for th!' lunar landing modules (which use air suspension legs, by~ the way). Each strut of the Monotrack suspension consists of a steel plunger operating piston.fasion inside an alloy tube, which is closed at the top except for a hose outlet, leading to a central accumulator. When a bump is met, the pressure is transmitted hydraulically via the hose to the accumulator, where it forces against a diaphragm. Opposing the pressure, on the ot! side of the diaphragm, is about 150 lbs per square inch of air pressure, introduced into the accumulator by an air hose. Hanebrink admits the accumulator loses pressure over a period time, but this poses no problem, as he simply fills it to the prescribed pressure, using a conventional air compressor, and it stays up for a couple of weeks. Rebound action is limited by a cable shackle connecting each plunger with its tube. The complete suspension is simple as a stone ax, yet with metallutgy and machming tolerances as sophisticated as the latest lunar exploration module. The Montrack Engineering' air suspension setup is available to serious racers only, at a price of $135 complete, with a money-back guarantee of satisfaction. It appears to be the hot setup for road racing, motocross and cross country events. Monotrack's address is 959·A West 17th St., Costa Mesa, Calif. 92627. Phone (714) 548-9833. ~ w Z W ..J (,) >(,) • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •A • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • KONIS NOW FOR HONDA United States importers of Koni Dutch-made shock absorbers for motorcycles, announced that they have replace~ent s.uspension units for 350cc, 450cc and 750cc Honda models. Koni Adjustable' shocks were ridden under ~est in competition in the Baja and Mint and, were fitted to the racing bikes of such competition riders as Gary Nixon (Tri) , Yvon Duhamel (Yam), Rusty Bradley (Kaw), Eddie Moran (Kaw) , Don Emde (Yam), Dave Smith (Kaw), Chuck and Larry Palmgren (Tri) and Kurt Liebman (BMW). DON'T FORGET CASH PURSE PHOENIX INTERNATIONAL MOTOCROSS and START MONEY ) DEC 20 MOTO-I-MAS classes to be contested: 125, 250 & 500 National, Sportsman & Professional Practice 10:00 AM First Race: NOON All out of state entries please contact IRE of Phoenix at (602) 264-0815 for entry information and information regarding expenses and accommodations. AT OAK CREEK RANCH CASH FOR SRS. GOLD FOR JRS. Terrain: An unreal course with long hills, sr:nall mud section, banked esses, jumps and extra wide. Information: (602) 264-0815 . Directions: Black Canyon Freeway (Inter State 17) from Phoenix to Deer Valley Road off ramp, turn left to the race track. ~;;;;,;,;,;,;~~;";",,;,,o,;; __ • _ ..'.... ~ _.-.-._-_. _ _.• I- • • • • •••••••~. _ .. ' ... . ,'4..~•••••• ~ • ,... ;r4b..NJJ .J • ••

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