gerry visser komt met lichtere XC modellen

[cyclopedia]

Gerry Visser heeft samen met Keith Bontrager nog eens naar de Geometrie van de XC bikes gekeken en kwam tot de conclusie dat het mogelijk is om de xc fietsen een lichter en sneller gevoel te geven door de voorwielas iets verder van de stuuras te plaatsen.

R. Cunningham

Gary Fisher Cycles has overturned a stone that fork makers have been ignoring for many years. The Fisher folks were concerned about how to lighten up the slow-speed steering of its Cake. Fisher consulted with respected frame builder Keith Bontrager, who suggested that they increase the fork offset (the distance that the front axle is offset forward of the steering axis). Increasing the fork offset would reduce the amount of “trail” in the steering geometry and give the Cake’s front end a lighter, quicker feel at singletrack speeds. Fisher’s marketing wing dubbed it: Genesis 2.0, and it will appear on the ’07 HiFi line of lightweight cross-country suspension bikes.


The offset of almost every suspension fork made measures 1.5 inches, because that is the number that worked best for the predominantly steep frame geometry that was used when suspension forks were developed. The problem is; the perfect amount of fork offset varies with different head angles, wheel diameters, and with changes in speed.

Genesis 2 steering would be a welcome boost for Gary Fisher's Fat Possum, which is super-stable in a straight line, but heavy handed in the corners. Why? Frame geometry became slacker to accommodate longer-stroke forks and more aggressive riding styles. Fork makers and frame designers, however, did not factor in fork offset and trail into the equation. The one-offset-fits-all standard was a money saver for fork makers, but, as Gary FisherÂ’s designers discovered, it could be a detriment to handling.

FisherÂ’s discovery is actually a rediscovery, because the very first mountain bikes that Gary produced (remember Ritchey Mountain Bikes) had almost two inches of fork offset, slightly slacker head angles than todayÂ’s racing sleds and steered beautifully. In fact, GaryÂ’s early steering geometry was copied by almost every mountain bike maker of that time. When NORBA cross-country racing took the country by storm, and head angles approached 72 degrees, cutting-edge designers like Keith Bontrager discovered that reducing the fork offset (which increases trail) added a much needed dose of stability to the nervous-handling racers. When Paul Turner launched Rock Shox, he adopted the shorter, 1.5-inch offset as his standard and all other suspension makers followed Rock ShoxÂ’s lead.

Today, riders are choosing slacker head angles, longer-stroke suspension and fatter tires—all of which have a damping effect on the bike’s slow speed steering. It was only a matter of time that some hot shot would rediscover the miracle of fork offset and apply it to a modern trailbike.

Kudos to Gary Fisher and Keith Bontrager for reintroducing a long-forgotten aspect of a proper mountain bikeÂ’s handling. We should also thank the folks at Manitou for retooling their suspension forks with additional offset to prove and then produce the G2 front suspension for FisherÂ’s Â’07 designs.

The bad part about this (there is always a dark side to innovation) is that, once G2 is accepted as a relevant improvement, every big-brand bike maker is going to claim they have superior knowledge of rake, trail and offset, and invariably will then order up forks with wildly different offset measurements. For a short period, there will probably be as many mountain bikes made worse by this “new” tuning feature as will be made to handle better. And I haven’t mentioned what a mess that G2 is going to make of the aftermarket and replacement fork process. Here we go again.

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