Cycle News - Archive Issues - 1980's

00 C') When the A-Trek (topllslnstalled (abovellt's barely visible. But it sure works. By Dale Brown Pity your poor rear shocks. They get pushed, pulled, expanded, compressed et al. And that's before they have to deal with bumps, potholes, railroad crossings, freeway expansion joints or whatever else lurks 'de h ' were you n . The guilty party is the series of torque forces transferred from 26 .. . cham to swmgarm to suspensIon. T~ey extend the s~ock under accel~ratlon and compress It u~er deceleration. So .the shocks are fighting one battle ~ven before the road hazards even begm to appear. What if you could neutralize those forces? Perhaps your susponsion would be free to work unencumbered. reacting the same way regardless of whether )VU were under heavy acceleration. hard on the brakes, or any combination thereof. Well, .you can.. . Austnan Horst.Leltner. a? engmeer who rode on hIS country s Trophy Team in the ISDT, 1961.64, has designed the A-Trak suspension system. It's a fairly simp.le device, consisting of two rollers connected by a body that' serves to mount the device around the swingann pivot. The rollers run on four double-sealed bearings. . Stock, your chain runs in a triangle and allows the torque reaction to be transmitted to the sus~sion. The A· Trak simply spreads t1ie chain apan at the swingarm pivot, and maltes the chain run parallel to the swingarm. That constant alignment, for reasons that are difficult for non-engineers to understand or explain, eliminates the torque reaction. We showed up at Leitner's TUItin, CA, headquaners with a 1981 Honda CB900F that we were testing at the time. Before Horst started to work on the bike, he showed us a little trick that you can perform on your own machine. He fired it up, held the front wheel in place with a curb and the front brake, and then he put it in gear, gave it some gas and staTted to let out the clutch. Sure enough. the rear shocks extended. even though the weight on the machine remained the same. ~ Demonstrations concluded. Leitner set to work on installing the A-Trak .. As it turned out. the 900F is one of the most difficult machines on which to install an A·Trak. A metal tab on the IWingarm had to be ground down 10 dlat the ATK ~ fit around the pivot point. Then the cue guard around the countenhaft sprocket had to be ground'dcnm at both ends to accept the modified chain angle. Leitner did it with the IWingarm on the bike, but recommeods dlat CB900F owners installing their own remove the swingarm completely. In most other t'a.ses, installation is a bolt-on affair, requiring only temporary removal of doo-dads (lilte sidecoven) that get in your way, and loosening the rear wheel to give you lOme chain slack. Once fully itlStalled - in our cue, in about 90 minutes - the bike was ready to ride. The A-Trait was barely visible behind the frame tubes and cue cover. As a final step, Leitner took the VHD shocks on the Honda and reset the pre-load from the middle setting to the fifth and stiffest setting. Compression damping was switched from soft to firm. Rebound damping - set at one - was left alone. Before we left, there was a repeat of the demonstration done pre-ATK. Everything was the same, front wheel held in place, gas on, clutch staning to grab. But the rear shocks stayed exactly where the) were. No extension or rise whatsoever. Once we hit the road, the bike felt good - it was good stock by our opinion. But the A-Trait was doing something. The ride was a Iinle bit softer and plusher, yet the shocks had been stiffened t.o the point where it should have been noticeable. One other thing that was immediately noticeable was that quick downshifts produced less tire squeal. A section of road we ride regularly - you can find it listed under the "Don'ts" section of Pavement Repair: Dos and Don'ts - is more like freeform sculpture than civilized tarmac. With the A-Trait, the Honda sailed through it like all the bumps weren't there. We tried it under hard acceleration, under braking, coasting through, and the results were the same each time. The rear suspension soaked up everything. Because the shocks are working unencumbered, the) can keep the rear wheel in contact with the ground through rough comers, aiding control. A staffer here had 'an A-Trait installed on his Yamaha and swears by it, saying it allows him to come off the corners faster due to improved traction. When the A-Trak is first installed you can hear some additional noise as the chain passes over the two rollers. After an afternoon of riding, you won't notice it anymore. Another minor point: this monl e F rider noticed was that when the shocks were stiffened to adjust to the A-Trait, there was no sag left. Instant tippy-toe time. We came away impressed with the A-Trait. For the average rider, it makes the rear suspension work the way it DeVer could before. The increase in rear wheel traction should malte racer types happy. The bolt-on A-Trak retails fOT $109_95, and is available for most latemodel street Hondas, Suzukis, Kawasakis and Yamahas. There are weld-on kits to fit most other types of bikes. ATrak units for Harle)-Davidsons and off-road application are in the works. ~itner offers a six-month warranty. Leitner recently introduced complete aluminum swingarms with integral ATrak for 1978-80 Honda CBXs, '79'81 CB750Fs. and the '81 CB900F. Suggested retail is $295. Leitner Corporation Z650-D Walnut Ave. Tustin, CA 92680 7141731-51 H.

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