Why inverted forks?

Whats the benefit and why do some people love them? Why do dirt bikes run them?

 

I had a Shiver for a long time. It was a very nice fork albeit heavy. Some people love 'em, some people hate 'em...

I have no clue why motorcycles use them only?

Mine was butter smooth, I got a new (to me) light DH frame and having a heavy fork wasn't really a good move...that's the only reason I no longer have it.

When I was @ Whistler I had about 12 people ask me if it was for sale...


A lot of people say that they are "flexy!"

Not too many are made nowadays, I know that there is a new Dorado out but it costs like 2K for the fork. Mine was an '05 and that was the last year that they were made.

One of the reasons that I loved it was I ran a 3" front tire at the time. The bike in the photo weighed 54 lbs....

 

ive ridden a bike that had the old dorado on it, and to me the fork "feels" lighter, just because the majority of the weight is so close to the bike.

im not sure the reason behind the mechanics of having the fork upside down is better or worse. but im sure mx bikes use them like that for strength.

i want the new dorado, im just not sure if ill pay that much for a fork. i might need to get talked into it.

 

I would think that it helps keep oil in the seals:-k
Other than that it looks cool!

 

Since the upper, heavier, tubes are attached to the chassis and not the wheel, it cuts down on un-sprung weight. Less is better when it comes to un-sprung weight because lower un-sprung weight lets the wheels respond better to the terrain.

The second main benefit is better steering through the corners because the inverted fork configuration is torsionally stiffer. There's less flex in the front end, so the front wheel goes where it's pointed.

Finally, you get better ground clearance because inverted forks have little to none of the fork leg hanging below the axle.

Yeah, they look cool too.

 

http://www.yamaha-motor.ca/technology/technology.php?group=M&tech=IF

 

Real sexy w/o wheel crown. One drawback would be protection against crashes and rock dings, which is the reason for the protectors on MTBs and dirt bikes when using the inverted forks. Don't know about you but that is where all the dings are on my forks - the lower.

 

I totally didn't even think of the unsprung weight. That has to be a lot of the reason.

 

You could say "unsprung weight" but on an MTB it's pretty relative. With a through axle the design yields higher strength to weight and can be more tuneable. The main draw back is that the tolerance on a moto can be a lot tighter due to the higher weight and loads. To build a MTB fork similarly would create too much stiction which is why some of the designs out there weep a bit, making the seals any tighter will only bind things up. Pretty much why it's only used on high end and/or DH applications, may need a little more maintenance but can be tuned to a higher degree that few would even notice. O.E.M. is a big reason you wont see anything more than standard spec on most bikes, the added cost and spare availability has yet to pan out and probably 75% of riders just switch to a standard.:?:

What's it to you?.

 

I don't think that unsprung weight is not as important just because it's a mtn bike. Look at the entire effort Honda did to make a gearbox, to just get rid of unsprung weight from the cassette and rear der. That's certainly lighter than the lower and oil from a fork.

 

It exceeds cost to benefit, if the entire production shifted most would not trust it.

Yeah but you are also raising the center of gravity, not to mention potential weight savings are grams not pounds. Although theoretically most of the parts could swap over it just not economically viable, and is Honda still racing DH anymore?

 

No they are not. They only made the DH bike for R&D for motorcycles. When they got all the data, the bike was retired.

 

because the look cool..... y else would i like it....

I'll talk you into it.......

JUST DO IT!!!!!! all the cool kids are doing it...

 

It was totally not economically viable because they made only like 2 prototypes. But the results more than spoke for themselves. They won championships both years they were in it.

I heard it was just a pet project for the head guy because he loved DH racing. Got into it, kicked ass and took names, and said peace out.

 

Kinda sounds like the Ford GT 40 saga. " hey Enzo we would like to buy your company" says Henry Ford. "Oh really, but we dont sell to American Companies"." Thats OK we will whoop your ass in LeMans then have a good day". 1st, 2nd, 3rd photo finish, OK we are done.:clap:

 

92se-r is correct in this little debate. Anybody with some motorsport knowledge know this. Is it worth the cost on a MTB, :?:

 

Increased inner/outer tube overlap, less axle overhang

The main advantages of an inverted fork for motorcycles is increased overlap between inner and outer fork tubes. The long outer fork tubes of an inverted fork allows the distance between the bushings to be increased. When you try and extend the overlap on a conventional fork you have to increase the front axle underhang. Many motocross and supercross tracks have very deep ruts that catch on the fork lowers; as you can imagine the ruts can take over steering the bike.
Using a conventional fork on a mountain bike has the advantage of four (4) brace points (upper crown, lower crown, fork brace and axle). An inverted fork only has three (3) brace points since you can't use a fork brace (front tire would hit it as the fork compresses). This problem can be minimized by using a larger axle/hub combination, stronger/stiffer crowns, redesigning the lower crown to brace the outer tubes at a more central point and utilizing larger diameter fork tubes.
Note: Motocross motorcycles use 11" to 12" of fork travel, most downhill bikes have 7" to 8" of travel. The axle overhang issue would be a problem for bicycles if they used the same length of travel as a motocross motorcycle.

 

well othert hen the sprung/unsprung weight, for motos, the extra clearance on the bottom og the fork makes a huge difference in glen helen ish ruts

 

that would look sick on my 951 all gold and red:-k

 

Gil: Hope my LAME attempt at photoshop will give you an idea of what it might look like!
My opinion: A black or *WHITE* fork would look good on that bike!



How cool would it be if SANTA dropped one off for Christmas...