Cycle News - Archive Issues - 1980's

CLeft! Mike Kldd's A·Trek-equlpped YZ486 wes the.highest piecing 'non-factory bike at The !>uperblkera.lTop right) The A-Trek on the 465. (Above middle) 1nst8llet1on requires removel or loosening of the chain, pulling the swlngarm bolt end bolting the A-Trek In piece. (Above right) Completed instelletlon. Procluet evaluation Dirt alert A·Trak- arrives By Mark Kariya Riding any motorcycle quickly, whether you compete against others, the clock or yourself, boils down to a single, basic premise (that, in theory, should be quite simple) - maintaining control. Of course, the faster you go, or the trickier the terrain, the harder it is to keep both wheels on the ground underneath you. That is where suspension. comes in. Thanks to modern motorcycle suspension systems, today's riders are able to conquer whoops, ruts, hills and much more at greater speeds and in more comfort than was thought possible 10 yearsagq. And while motorcycle evolution stiD motors onward, it seems to be doing so in small steps instead of CJuantum leaps. Almost every month bnngs some new or improved idea aimed at the competitive riqer. The A-Trait suspension system is one such idea. With his product in use on street bikes for over a year, designer Horst Leitner, a former Austrian ISDT rider, has spent much of this year getting ATrak tested and developed on dirt bikes. Two riders have done much of the testing (and winning) with ATrait-equipped bikes Curtis Cannon, a l11-year-old southern California dirt track whiz, and Mike Balter, another SoCal rider who is a top notch grand prix rider as well as a proficient motocrouer. The A"Trak system was favorably evaluated on a Honda CB900F in issue 126 of Cycle News, but for those who don't remember or (heaven forbid) didn't read it. the A-Trak is a pretty simple device. Basically, there are two rollers, one above and one below the swingarm pivot, connected by two pieces of machined aluminum flat stock. Call it a chain guide or chain tensioner or whatever, but the rollers spread the chain apart at the swingarm pivot until the chain is almost running parallel to the swingarm. This does two things: 1) the chain can be adjusted until there is very little slack, and 2) according to Leitner, it eliminates the torque reaction of the chain on rear suspension components. It is the second item that Leitner claims does the most good. Widiout the A-Trait, wheneve~ throttle is applied, the chain-caused torque reaction extends the shock (or shocks) which effectively stiffens it. When the throttle is shut, rhe opposite happens. What this does when riding is malte the rear end of the bike harsher and less sensitive to bumps under acceleration and spongy under trailing throttle. With the A-Trait, and no torq~e reaction, the shock should, theoretically, be free to do the job for which it was designed under all circumstances. In other words. it should make maintaining control of the bike easier. To see if theory actually worked in real-world situations, we go~ together with Leitner at Saddleback Park for an afternoon of riding. He brought out two virtually identical bikes for us to ride around, 1981 Can-Am 250 Qualifiers. Both bikes had the A-Trak and reasonably fresh tires but were otherwise bone stock. After riding both bikes to ascertain that they performed the same, the A-Trak on one bike was removed. Installation, or removal, of the unit was quite simple and quickly accomplished. In brief, all that. is necessary is to loosen the chain, pull the swingarm pivot bolt out, slide the A-Trait into place over the front of the swingarm, center and adjust things, then go ride. Instructions are included with. each unit, and it should take no longer than a half hour of your time to get it together. Out on the track or trail, the only difference immediately discernible was the absence of noise due to the chain flopping around. However, more riding time revealed that the A-Trakequipped bike felt a little plusher on sharp-edged bumps and didn't seem to kick around quite as much, even with the stock old gas Girlings. Climbing hills was another area in which the bike with A-Trak felt like it had a slight advantage. Again, the rear wheel didn't seem to spend as much time bouncing in the air. If both bikes were stopped near the top of a loose, rock-strewn uphill, the scooter with A-Trak felt like the rear wheel spent more time getting traction than hunting for it. Leitner claims that the more powerful the bike and the more torque it produces, the more difference will be noticed when the A-Trait is installed. Naturally: seat:of-the-pants impressions are one thing; lap times around a track are another. Thus, timed laps around one of Saddleback's motocross tracks were in order. The objective was not to go as fast as absolutely possible, but to ride at a rapid and consistent pace, one that would be fast yet not so fast as to cause time-consuming mistakes. Due to dwindling daylight, we elected to run bu t three laps on each bike starting with the A-Traked one. It felt OK, no major errors that would throw the timing off were committed, and the three laps went by quickly enough. On the bike sans A-Trak, the same lines and bralting points were used as we tried to duplicate the first ride as much as possible. However, it felt like we were going faster on the second ride. "Hmm, might just be that Horst is wrong about this thing." Nope. As it turned out, each lap with the A- Trak bike was quicker (by 1.5, 1. 7 and 1.6 seconds on a track that took us in the low I :50s to lap), and lap times are the bottom line. . Realize, of course, that this was a very unscientific way of reaching any firm conclusion. Optimally, we'd like to try. the A-Trak on different bikes, different tracks and with different riders using light beam-triggered electronic timers, but time and money prevent us from doing so. Initial impressions of the A-Trak suspension system on dirt bikes, though, are favorable. Besides many local race wins, A-Trak bikes have done well in bigger races like Pike's Peak and The Superbikers III where a trio of YZ465s entered under the Dallas Baker Products banner took third in team competition behind Team Honda and Team Maico. Rider Mike Kidd was the first non-factory bike, beaten .out of fifth by Yamaha's GP motocrosser Hakan Carlqvist on the last lap. Should you buy one? At $109 they're not cheap, but they appear to do what they're claimed to. There are models to fit almost any bike including late model Can-Arns, Honda CRs and XRs, Huskys, Kawasaki KDXs, KLXs and KXs, Suzuki PEs and RMs and Yamaha ITs and YZS. In addition, there are universal models for other applications, either left or right-hand drive chains. Leitner Corporation 2650-D Walnut Ave. Tustin, CA 92680 714/731-5114 •

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