After a successful partnership with Specialized in coming up with the Brain shock for the Epic series, Fox has proceeded to introduce their TerraLogic forks that feature the same inertia valve technology. Akin to its close cousin, the TerraLogic forks are able to distinguish between rider-induced forces from bumps on the trail. This enables the fork to be lockout on smooth roads and fully active when the going gets bumpy.

The Family Tree

Currently, the TerraLogic forks only come in two models, the F80X and F100X. The numbers simply reflects the amount of travel each model has. With the ?brain? handling the lockout function, the other adjustments available to the rider are the preload adjustment, rebound damping and bump sensitivity threshold. Both forks weigh in the region of 3.5 lbs.

Quality and Stiffness

Fox fork are highly regarded for their steering precision, quality suspension travel, easy adjust ability and good durability. Good steering control and stiffness on the Fox fork is achieve by the chunky 32mm stanchion tubes coupled with long overlap between the stanchion and lower legs. If you are observant, you will notice that the expose stanchion on the F80X is only about 83mm as compared to 130mm in a 80mm travel SID. This translates to longer service life for the bushing and less flex fore & aft.

Is the Brain senile?

When the inertia valve technology was first introduced, many were skeptical about it. It seems more like a marketing gimmick than an essential feature for the riders. Flipping the lockout switch on the fork was never a paramount task in the first place. We believe that, most cyclists would prefer to have total control over their fork, than to leave it to some hi-tech gizmo.

The first difficulty comes when we are setting the preload. Since the fork?s neutral state is in lockout mode, to adjust for sag, the rider got to first activate the inertia valve by lifting and dropping the front, jump onto the bike in a split second and capture the sag amount. Patience is definitely a virtue when carrying out this task.

After setting up the preload and threshold sensitivity, it is time to check out the Brain.

Fox Fork TerraLogic F80X Review (Continued)

This fork truly shines under off-road conditions. Tracking is extremely good thanks to its 32mm stanchion tube which provides excellent torsional stiffness. Point the fork in your intended direction, and it will follow through with minimal deflection. The inertia valve also performs flawlessly when we transit between tar roads and the trails. Slight delay in the opening of the valve can only be felt on the first bump. However, this does not hinder the fork?s capability in jumping off the kerb. The fork cushions the impact brilliantly when the front end landed.

The valve will stay open as long as it keeps sensing bumps from the ground. No energy was lost for out of the saddle sprint along smoother trails. And when the ground starts getting bumpy, you will notice the fork subtly smoothening out the unevenness and maintaining good front-end traction.

To tune the bump responsiveness of the fork, simply play around with the threshold sensitivity knob. This knob will decide the size of the bump that will open the inertia valve.

Is the technology worth it?

At about $150 more than the Float 80RLT, it might be difficult for some to justify paying that amount for a feature they think they can do without. Ultimately, it all boils down to what you are looking for in your fork.

If you are a control freak that wants everything to work precisely as and when you want it to, then you might be better of with the Float 80RLT. You definitely would not want to be caught in a situation when you are about to execute a bunny hop, but not knowing whether the fork is on or off.

On the other hand, the F80X will be a weapon of choice for those aggressive XC riders out there who are seeking out a super efficient fork with little or no user intervention during the ride. On this fork, you will be as efficient as you could be on any cross-country trail. Forgetting to lockout when on the smooth or vice versa is a thing of the past. The only small imperfection you got to live with is the slight delay when overcoming the first bump.

As an addendum, We’ve included the warranty notice provided by Kian Hong Cycles has been provided for your reference.


? The warranty period for your fork is one year from the original date of purchase of the bicycle or fork. A copy of the original purchase receipt must accompany any fork being considered for warranty service. Warranty is at the fulldiscretion of Kian Hong Cycle and will cover only defective materials and workmanship.? Note that Kian Hong Cycle will only service warranty claim of aftermarket fork which bears the warranty sticker shown on the right.
? Parts, components and assemblies subject to normal wear and tear are not covered under this warranty.
? Kian Hong Cycle reserves the right to all final warranty or non-warranty decisions.

General Exclusions from this warranty shall include but are not limited to any failures caused by:
Installation of parts or accessories that are not qualitatively equivalent to genuine FOX Racing Shox parts.
– Abnormal strain, neglect, abuse and/or misuse.
– Accident or collision damage.
– Modification of original parts.
– Lack of proper maintenance.
– Shipping damages or loss (purchase of full value insurance is recommended)
– Damage to interior or exterior caused by improper cable routing, rocks, crashes or improper installation.
– Oil change or service not performed by FOX Racing Shox or an Authorized Service Center.

Specific Exclusions from this warranty shall include:
? Parts replaced due to normal wear and tear and/or routine maintenance.
? Parts subject to normal wear and tear and/or routine maintenance: bushings, seals, suspension fluids, drop-outs

Kian Hong Cycle makes no other warranty of any kind, expressed or implied. All implied warranties of mechantability and fitness for a particular purpose which exceed the obligations and time limits stated in this warranty are hereby disclaimed by Kian Hong Cycle and excluded from this warranty.

Warranty Q & A

Q. Why will Kian Hong Cycle not service my aftermarket fork that does not come with the warranty sticker?
A. All aftermarket FOX FORX distributed by Kian Hong Cycle are identified by a grey warranty sticker (see above). The warranty of these forks is fully supported by Kian Hong Cycle and the claims are free during the warranty period. Kian Hong Cycle does not service aftermarket forks without the stickers as the forks originated from other grey market sources.

Q. How do I make sure that a fork is aftermarket?
A. All aftermarket forks should come with a box, owner?s manual, pump or spare springs. In addition, the bottom of the steerer tube should be engraved with the markings ?XXXXX-XXXXX-X-AM? instead of ?XXXXX-XXXXX-X-OE ONLY?. Most importantly, make sure it comes with warranty stickers on the steerer tube and the rear right leg when making a purchase.

Q. What should I do when making a warranty claim?
A. In the event of a fault during the warranty period, send in the fork together with the original receipt directly to us or via the bike shop where it is purchased (the latter recommended for overseas customers). Complete the FOX Service Record form available for download from or submit with your claim a copy of your particulars and a brief description of the problem.

Q. What costs are my responsibility during the warranty period?
A. The customer is responsible for all costs of maintenance services, non-warranty repairs, accident and collision damages, oil, seals, bushings and reducers, and mounting hardware.

Q. What are some examples of ?abnormal? strain, neglect or abuse?
A. These terms are general and overlap each other in areas. Specific examples are: hucking, ghost riding, big drop, stunt/ dare-devil riding, riding with broken parts, riding without oil in fork, wrong spring rate, etc.

Q. Does the warranty cover incidental cost such as shipping or transportation?
A. No. The warranty is limited to repair of materials and/or workmanship.

Q. May I perform any or all the recommended maintenance shown in the owner?s manual?
A. You may perform seal and suspension fluid maintenance as well as bushing and drop-out inspections. If bushing or drop-outs are worn, they should be replaced by an Authorized Service Center.

Q. May I perform service and repairs on my fork?
A. FOX FORX are mostly end user serviceable. Oil and travel changes and damper or spring replacement can be performed by the consumer. To ensure peak performance, extensive repairs and service to the fork should be performed by an Authorized Service Center. If in doubt as to whether or not you are capable of fixing your fork, kindly contact Kian Hong Cycle.


Kian Hong Cycle is not responsible for any damages to you or others arising from riding, transporting, or other use of your component or bicycle. In the event that your component breaks or malfunctions, Kian Hong Cycle shall have no liability or obligation beyond the repair or replacement of your component pursuant to the terms outlined in the warranty provisions of this document.