There is good news: Bob is about to be banished. Since the beginning of time in the world of mountain bike suspension, bob has been THE industry demon, sapping precious energy with each pedal stroke and weight shift – translating into less-than-optimal forward motion. But over the past year, various designs of stable platform suspension shocks for both front and rear ends have made inroads into the off-road bike market. Bob is finally facing up to reckoning after reckoning with each race season, not least of which from the Fox Racing Shox range of Terralogic forks and ProPedal rear shocks.
The F100X is the 100mm version of the F80X Terralogic, and I have used the former over a test period of one month and the latter for well over a year. The F100X weighs in at 1.62 kilograms uncut. It features an air-sprung preload shock assembly in the left leg. What is more interesting is the Terralogic assembly in the right leg. The guts of the right fork leg and lowers house what is essentially an inertia release valve to control the flow of oil from the damper unit. When the front wheel contacts a bump, a brass mass that originally contacts a piston on the inside is displaced by input from that bump (not the rider), opening the way for oil to flow from the damper and for the fork to commence the compression stroke. As soon as the bump is past, the brass mass settles back into place, such that oil flows back into the damper on the rebound stroke, locking out the entire system once more. This leaves the rider free to hammer the smooth flats without bobbing until the next bump in the trail. On other fronts, the Fox crew has upgraded the bushings on the 05 range over the previous year’s range, citing that there would be improved durability and reduced friction. As far as aesthetics go for Fox’s 2005 line, the previous year’s predominantly blue-silver decal theme has been replaced by a cleaner, cool grey motif and larger ‘Fox Tail’ logos.
There is an adjustment knob on the bottom of the right leg that allows riders to adjust the sensitivity of their fork to bumps. It has 22 clicks of adjustment, and we found that setting the knob 5 clicks short of the most sensitive setting was sufficient to keep us honest on the trails. For rebound speed, we picked the middle ground out of 12 possible speed settings at 6 clicks in either direction. No lock-out lever to fool with – just a fit-and-forget ride, and having no worries of hitting the blow-off threshold of other manual lock-out fork models and potentially damaging their internals. Preload is tweaked according to the rider’s weight, although we found that setting the fork really plush reduced travel to that of an 80mm fork. Cross country whippets used to setting up harsh front ends are advised to stick to the first-timer’s recommendations in the Fox owner’s manual, as the rigidity of the auto-lockout mechanism negates the use of such stiff settings, even for race purposes.
Given the unique nature of its lock-out design, we found that road riding duties come as a natural forte for this cross-country fork, particularly on urban streets with high traffic volume. The Terralogic endears itself to riders who need their front end to remain locked out when accelerating the bike out of a standing start (traffic lights). Likewise when sprinting away from hairy situations (motor vehicles/other riders), or railing and accelerating through corners – frenzied rider movements and pedaling forces do nothing to create bob on this fork.
In its original element of off-road riding, the Terralogic facilitates climbing efforts with rigid-like efficiency, yet opens up on the bumps – with nary a lockout lever in sight. Generous applications of the front brakes would cause most forks to dive, depending on the initial setting-up, and alter the geometry and weight distribution of the rider and bike – a potentially risky phenomenon with inexperienced riders and/or steeper downhills. Not so with the Terralogic: compression on a brake-heavy descent only occurs when the rubber rolls over a bump or drop. The lack of having to constantly worry over the status of one’s suspension lockout leaves one to concentrate on other pertinent concerns in order to improve ride quality, such as pedaling faster, picking a better line, or observing squirrels in the surrounding trees.
For the key litmus test, we took the F100X to the Action Asia Challenge Singapore sprint adventure race. We pumped our knobbies up to 60psi but left the fork air pressure and rebound settings untouched. With most of the bike legs consisting of road and tarmac, the F100X was right at home remaining locked-out for the most part, conserving rider energy. For another portion of the course, we rode in a monsoon drain on treacherously damp, algae-ridden concrete, where the slightest twitchiness and loss of traction from the front wheel would result in a spill. The F100X reacted to the unexpected bumps and debris of the drain instantly, maintaining front wheel direction even at high speed. For the Bukit Timah leg, our test fork sailed through and soaked up the closely spaced stutter bumps of the descents. Yet on the steep climbs, our old nemesis bob was virtually non-existent, allowing even the slowest of granny-gear ascents with little loss of power transmission from pedals to rear wheel. We felt first-hand, hallmark Fox high torsional and lateral rigidity of the fork over rough ground, which gave rise to accurate tracking and precise steering in all conditions. This remains as a hallmark characteristic of Fox forks – afforded by the robust but lightweight one-piece arched crown and lower leg assembly and 32mm stanchions.
We came away impressed with the F100X. While it carries with it a substantial price tag, it is undeniably the weapon of choice for efficiency-mad cross-country racers and endurance bikers seeking a fork that has stood the test of time. The features it offers would be hard to pass up in this day and age where bob is increasingly hunted down and eliminated for the betterment of all mountain biker-kind.
Our test rig consisted of a 2003 Scott USA Team Issue, generously provided by Sdiann at Kian Hong Pte. Ltd. The business end of the bike, apart from the test fork already in place, consisted of Hutchinson Airlight Scorpion Tires, Mavic CrossrideWheels laced in a radial configuration, and XTR V-brakes and XT brake levers from the Big S.