Fox Prototype Inverted DH fork

[Nikolais]

http://www.pinkbike.com/news/Fox-Prototype-Inverted-DH-fork-World-Exclusive.html

[Capricorn]

yeah.. i've been wondering what the big news Fox was hinting at previously. i think Trek also dangled the damn hint. thanks for the scoop Niko

 

but honestly, now thati think about it, this has been done before. just cos Fox does it. bigwhoop? me thinks not. But big up to Fox for going down this well ridden road. Nonetheless,i'm very curious as to Fox's design intent, and what shortcomings they are addressing in their current lineup, or shortcoming in the normal design of an MTB fork..

 

that first comment under the article on PB prettymuch sums it all up.

Edited May 30, 2011 by Jarek Wysocki

[LazyTrailRider]

Nonetheless,i'm very curious as to Fox's design intent, and what shortcomings they are addressing in their current lineup, or shortcoming in the normal design of an MTB fork..

 

WWJBD?

 

(What would Johan Bornman do?)

 

He'd say: "Ask yourself, what problem does it solve?"

[Capricorn]

lol MH @ WWJBD..

[Eddy Gordo]

Reminds of of the upside down forks that you get on motor bikes.

[Wernervdmerwe]

I know I might get flamed by the JB himself, but Maverick have been making inverted forks for a long time now and they're very highly rated.

 

Their reasons:

 

INVERTED DESIGNTake a close look at either Maverick fork and you see that the design is inverted from a traditional mountain bike fork design. The stanchions that are traditionally at the top of the fork are on the bottom. The advantages to this inverted fork design are many:

 

• Gravity is keeping the lubricity of your fork at a maximum. Oil is always being forced onto the seals and sliders by gravity, resulting in a smoother fork, all of the time.

• The stanchions are not up by the tire getting mud, dirt and rocks flicked at them all the time. Since the integrity of the fork relies on the stanchions sliding through the seals without leaking, it definitely makes sense to position them out of harm’s way.

• Allows us to use rock-solid uppers, which suspend the weight better and allow the wheel to be more active in the bumps.

• By placing the larger tubes at the highest-stress part of the fork, you get better fore, aft, and lateral stiffness.

• Our design is light. In fact, the DUC32 is the lightest 6” travel fork around (3.9lbs).

 

Overall, the result of our inverted design is more active suspension, a better ride, and more control.

[Wernervdmerwe]

And, although more in the motorcycle side of things - this the reasons from Yamaha:

 

http://www.yamaha-motor.ca/cached/be4b1fc0ed21e519aa02b04057d04aff.gif

 

Inverted forks are positioned on the motorcycle opposite or upside down when compared to conventional forks. The leverage forces that cause fork flex are greatest at the triple clamp area and weakest at the front axle. On inverted forks, the large outer tube of the fork is clamped in the bike’s triple clamps and the sliding inner tube holds the axle and front wheel. By locating the large diameter tubes in the triple clamp, the inverted or upside down fork have their largest and strongest parts combating the highest stress. This arrangement gives the forks high rigidity, which improves their response by reducing the side loading of the internal bushings (sliding surfaces). This kind of response is particularly important in high performance applications. Most inverted forks use cartridge-type damping systems.

 

 

 

 

[LazyTrailRider]

I have to admit that the unsprung weight thing seems like a good idea. Whether it's marketing-physics or not I don't know. I do know that the DNM UD180 upside-down DH fork my brother had on his Cannondale many years ago was the biggest piece of crap ever. Even with its massive axle and stanchions, it was way more flexy than my normal QR Revelation is today. On every run where you hit an off-camber section or a rut (yes, basically every run then) all the clamps had to be loosened and the whole thing straightened again to get rid of the massive stiction that a wheel run 10deg out of allignment causes. Absolute rubbish.

[Colin H]

And less unsprung mass giving better damper control

[LazyTrailRider]

And less unsprung mass giving better damper control

 

I haven't considered that... interesting concept...

[Nikolais]

I actually ride a pair of 2002 Shivers (Inverted) and absolutely love the forks.

I may not be World Champ material, but I definitely ride hard and have never had a problem with them. They are an awesome 'Privateer fork' as they perform buttery smooth for months and months between services.

 

I have never really felt the 'flex' much while riding, but this is explained in the PB article.

'The old argument of inverted forks having less torsional flex needs to be thrown out the window as it is far less relevant than most believe. Keeping in mind that the fork is well into its travel when being ridden, which stiffens the inverted chassis up greatly, the cliche test of pinching the front wheel between your legs and twisting really has no bearing in real world applications'

 

My one problem is that the lowers are subject to damage primarily on uplifts. That said I have ridden my forks since 2003 and didnt get one scratch until I lent the stanchion guards to a friend and didnt get them back for a year. Now i have one small scratch and a tiny dent from someones pedal on an uplift.

 

But i am not going to argue either. I dont really mind which way around my forks are - as long as they work and are easy/cheap to maintain.

[Nobody]

Arent all lefties (cannondale) inverted too?

[nickc]

Arent all lefties (cannondale) inverted too?

 

Yes.

[Azonic]

Old school riders should remember these. Came out in 1993.

 

http://mombat.org/894Halson.jpg

 

http://mombat.org/994HalsonForkAd.jpg

 

and for that matter...

 

http://mombat.org/Suspension.htm

Edited June 1, 2011 by Azonic