Inverted X-Fusion

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  • 08-29-2012
    honns
    Inverted X-Fusion
  • 08-29-2012
    Bike Whisperer
    Quote:

    Originally Posted by honns View Post

    Read the article

    Quote:

    It boils down to less unsprung weight (mass not supported by the suspension) that allows the suspension to react quicker to impacts, with another plus being that the fork's lubrication oil is likely to spend more time around the seals and bushings, thereby keeping the fork running smooth.
  • 08-29-2012
    CharacterZero
    Quote:

    Originally Posted by honns View Post

    If you had read the article you'd have already found the answer.

    edit: whisperer beat me to it!
  • 08-29-2012
    honns
    Missed the important paragraph, it would seem.
  • 08-29-2012
    mullen119
    If it becomes available, I will be the first in line to buy it. I want to upgrade my Lyrik to a Vengeance anyway, and I have always been a huge USD fork fan. At 155lbs, its a match made in heaven.
  • 08-29-2012
    Renegade
    " Why would X-Fusion, among others, pursue an inverted design, especially when it presents such a design challenge? It boils down to less unsprung weight (mass not supported by the suspension) that allows the suspension to react quicker to impacts, with another plus being that the fork's lubrication oil is likely to spend more time around the seals and bushings, thereby keeping the fork running smooth. "


    there you go
  • 08-29-2012
    Salespunk
    So sick! Hopefully they build it and it works.
  • 08-30-2012
    Kiwiplague
    Plus they look amazing! If they do nail the stiffness issues, they could be onto a winner with that fork.
  • 08-30-2012
    ryguy135
    Can anyone explain to me why all motocross bikes use inverted forks but mtb uses standard? I'm a mechanical engineer but this has me stumped. My buddy that rides both says Honda came out with a standard MX fork once but then everyone complained it was too flexy!?!?
  • 08-30-2012
    honns
    Yea, I see the benefits now. I'm with ryguy, why did the motorcycle world move to inverted? Seems like if it works better for the motorcycle world, it would also work better for MTB.
  • 08-30-2012
    steadite
    Quote:

    Originally Posted by ryguy135 View Post
    Can anyone explain to me why all motocross bikes use inverted forks but mtb uses standard? I'm a mechanical engineer but this has me stumped. My buddy that rides both says Honda came out with a standard MX fork once but then everyone complained it was too flexy!?!?

    Just guessing...maybe cause MTb has only recently had thru axle type connections. Couldn't do inverted with old style 9mm bicycle dropouts.
  • 08-30-2012
    ryguy135
    Quote:

    Originally Posted by steadite View Post
    Just guessing...maybe cause MTb has only recently had thru axle type connections. Couldn't do inverted with old style 9mm bicycle dropouts.

    Good guess, but this can't be it. Fox had a prototype inverted DH fork that Aaron Gwin had been spotted doing practice runs on at World Cup races. Here maybe 6 months ago though they made an official announcement saying they were abandoning development citing excessive flex as the reason.
  • 08-30-2012
    mullen119
    The larger diameter stanchions on motocross bikes allow for extra stiffness. There have been many attempts at inverted mtb forks, but larger riders still complain of flex. If someone makes a stiff USD fork, it would take over.
  • 08-30-2012
    beanbag
    I have enough scratches on my fork lowers that I wouldn't want my delicate stanchions to be in that area.

    This fork is stiffer than a standard fork in certain ways (front-back motion, for example), but seems much less stiff against the wheel tilting from side to side due to independent leg compressions.
  • 08-30-2012
    mullen119
    Assuming this fork ever makes it to production, I would be very surprised if it doesnt come with stanchion guards similar to what comes on the Manitou Dorado or White Brothers Groove. I would think they just kept them out of the picture to give a better look at the fork.

    Its long been said that to make a bicycle USD fork stiff enough(twisting wise), for larger riders and extremely aggressive riders, a larger diameter axle would be required. Manitous 20mm Hex axle is suppose to be the best thing at 20mm, but still suffers from some flex. At this point, nobody wants to make a 25mm axled fork that comes with a hub. They dont feel the market is big enough to have the inconvenience.
  • 08-30-2012
    Fix the Spade
    Quote:

    Originally Posted by honns View Post
    Benefits are what, exactly?

    It looks badass.
  • 08-30-2012
    Fix the Spade
    Quote:

    Originally Posted by steadite View Post
    Just guessing...maybe cause MTb has only recently had thru axle type connections. Couldn't do inverted with old style 9mm bicycle dropouts.

    Marzocchi were doing 20mm inverted Shivers in 2002, they were great forks relative to what else was available (like Psylos...) but did suffer from left-right twisting. Mine didn't, but I was 14 and weighed bugger all, big guys could get visible flap out of them.

    My guess is X Fusion have taken the keyed stanchions from the HiLo post and applied them to the inverted fork. If one little stanchion can resist twisting at the saddle, then two bigger ones bolted together should have no problems at the front wheel. As long as they stay in the uppers and avoid the wiper seals that should solve any twist issues.

    Regardless, I definately want one!
  • 08-30-2012
    David C
    Another issue so far with USD forks being stiffer is the weight. They are already heavier than most big forks on the market and to get a stiffer fork, you will need to either find a killer design or use stronger, but heavier materials and structure. And I'm pretty sure an inverted motocross fork weights a lot more than any MTB fork already. But I'm pretty sure they're gonna come up with something good one day, as carbon fiber, titanium, magnesium and other superior materials are being used in better ways and designs.
  • 08-30-2012
    mullen119
    I dont know, 4.3lbs for a 160mm fork is pretty damn light. Dorado's are pretty light at 6.6 lbs as well. There used to be a carbon legged Dorado but at 2400msrp, it didn't last very long.:lol:
  • 08-31-2012
    bad mechanic
    There's a reason every USB single crown fork has failed in the bicycle market. Without a second crown the fork cannot be made stiff enough without making it weigh a ton. Aside from that you're still dealing with more easily damaged stanchions and less wear/damage tolerant seals. Then at the end of the day the benefits from going USD on a bicycle are questionable.

    On a motorcycle weight doesn't matter nearly as much and USD forks can be beefed up to be stiff enough. You can also run tighter and better seals since the weight of the motorcycle makes it more tolerant of stiction.

    I really like X-Fusion, but it makes me sad they're wasting their resources on a evolutionary dead end.
  • 08-31-2012
    gabe0807
    Quote:

    Originally Posted by bad mechanic View Post
    There's a reason every USB single crown fork has failed in the bicycle market. Without a second crown the fork cannot be made stiff enough without making it weigh a ton. Aside from that you're still dealing with more easily damaged stanchions and less wear/damage tolerant seals. Then at the end of the day the benefits from going USD on a bicycle are questionable.

    On a motorcycle weight doesn't matter nearly as much and USD forks can be beefed up to be stiff enough. You can also run tighter and better seals since the weight of the motorcycle makes it more tolerant of stiction.

    I really like X-Fusion, but it makes me sad they're wasting their resources on a evolutionary dead end.

    But they look so coooooooool :D

    I've become a fan of X-Fusion stuff, but I am also a bit concerned about heading down this path. They already make good stuff that is way cheaper than the competition. Why not just go head-on into the DH scene with a traditional fork. There are no shortage of poor downhillers who will appreciate the value.

    I'll try to withhold judgement though. I hope its totally badass.
  • 08-31-2012
    OffCamber
    Just for fun. 2002 Marzocchi Shiver SC. My wife's retro Klunker.
  • 08-31-2012
    Fix the Spade
    Interesting note.

    There is an interview with the DVO suspension guys in this month's Dirt. There are no pictures but apparently DVO's new downhill fork will be inverted as well.

    Inverted revival time?
  • 08-31-2012
    mullen119
    You can't say they have all failed since a couple companies still make USD mtb forks. You can't say weight for motorcycles doesn't matter either. People spend hundreds of dollars on TI bolts for motocross bikes just to save a pound. The flex issue is real though, and its caused by the stanchions being able to twist inside the uppers. If x fusion had found a way to solve this, and they sound confident that they did, it could be a great step forward. Anyone who has ridden on a USD fork loves the feel they give, other then the twisting of course.
  • 08-31-2012
    Jon Richard
    Isn't Paul Turner of Maverick Bikes now in league with X-Fusion? I love my DUC32 forks for trail duty.
  • 08-31-2012
    bad mechanic
    Quote:

    Originally Posted by mullen119 View Post
    You can't say they have all failed since a couple companies still make USD mtb forks. You can't say weight for motorcycles doesn't matter either. People spend hundreds of dollars on TI bolts for motocross bikes just to save a pound. The flex issue is real though, and its caused by the stanchions being able to twist inside the uppers. If x fusion had found a way to solve this, and they sound confident that they did, it could be a great step forward. Anyone who has ridden on a USD fork loves the feel they give, other then the twisting of course.

    I said every single crown USD fork has failed, and they have. All the successful ones are dual crown, because the second crown is critical to making it stiff enough. A motorcycle, and motorcycle rider, is much more tolerant of an extra couple pounds on a fork considering the added performance, while on a bicycle an extra 100g is unacceptable.
  • 08-31-2012
    mullen119
    Quote:

    Originally Posted by bad mechanic View Post
    I said every single crown USD fork has failed, and they have. All the successful ones are dual crown, because the second crown is critical to making it stiff enough. A motorcycle, and motorcycle rider, is much more tolerant of an extra couple pounds on a fork considering the added performance, while on a bicycle an extra 100g is unacceptable.

    My bad, I read it on my phone and some how missed "single crown"

    I still disagree on the weight issue though. 4.3lbs is very light. Lyriks and a regular vengeance is close to 5lbs. Even if it was 100g more, I dont think that would be unacceptable if it performed well.
  • 09-01-2012
    semmiho
    I'm only guessing, but would it be possible that X-Fusion will put something similar needle bearing that Leftys have? Probably it's enough to put this kind of tech to the air/brake side and it will solve all issues that may come from the single crown and "only" 20mm thru-axle design.
    I'm looking forward for more info about the tech of this USD fork.
  • 09-01-2012
    beanbag
    Keying the stanchions still doesn't prevent independent leg compression.
  • 09-01-2012
    Jon Richard
    Quote:

    Originally Posted by beanbag View Post
    Keying the stanchions still doesn't prevent independent leg compression.

    No, but I would venture to say it would help with independent leg rotation. Maybe we ought to bring back the 24mm front axle to help mitigate independent leg compression.

    I wonder what my DUC32 would handle like if the stanchions were 36mm and keyed.
  • 09-01-2012
    Fix the Spade
    Quote:

    Originally Posted by beanbag View Post
    Keying the stanchions still doesn't prevent independent leg compression.

    But on a bike where both stanchions are connected by the thru axle and receiving forces from the same point is there any independent compression to prevent at all?

    I don't ever recall seeing it on motos, or even Dorados and Shivers. Twisting and fore-aft bending always seem to be the bug bears on mtb forks, especially the latter.
  • 09-01-2012
    Hardtails Are Better
    Quote:

    Originally Posted by Fix the Spade View Post
    But on a bike where both stanchions are connected by the thru axle and receiving forces from the same point is there any independent compression to prevent at all?

    I don't ever recall seeing it on motos, or even Dorados and Shivers. Twisting and fore-aft bending always seem to be the bug bears on mtb forks, especially the latter.

    Particularly since the spring and damper are in different legs, yes. But it's not a problem. a well designed 20mm axle is plenty burly enough to handle it. As has been noted, twisting is the biggest issue with an inverted fork, especially a single crown. The keyed stanchion thing should help there.
  • 09-01-2012
    mullen119
    I dont think independent leg compression is much of an issue. Its more about the stanchions spinning in the uppers that is the problem. Keying them would make a huge difference, but would make sealing them a problem.

    I will be very interested to read about the tech that they are using to help solve the problem. The Vengeance is one of the stiffest 160mm forks out right now. If the people at X fusion say its comparable, I am going to give them the benefit of the doubt. A Lyrik is pretty flexy in comparison to a Vengeance, so even if this new fork is similar in stiffness to a Lyrik, it would be plenty stiff for most people.
  • 09-01-2012
    beanbag
    I don't think stanchion spinning is much of an issue. First, you have the thru axle to prevent that, and it is much stiffer than the torsion traveling down a long length of tube. Second, this stanchion spinning is accompanied by one fork leg moving forwards and one backwards. (The twist that happens when you turn the handlebars but the wheel doesn't turn.) So there is another mechanism to prevent this motion anyway. Third, for stanchion keying to prevent this motion, it will basically have to have zero play and no excessive drag. With all that said, my guess that they will be keyed anyway just so the fork doesn't go loopy when you take off the wheel. But I doubt it has any other structural purpose.

    As for independent leg compression, the only thing prevent that on this fork is the clamping mechanism of the thru axle, bolted or press fit or glued to the end of a thin-wall stanchion. It will be easy to test just by grabbing the rim and fork leg together in one hand and squeezing.
  • 09-01-2012
    mullen119
    Lets be honest here, Its not like its a measurable amount of twisting that happens. The honest reality of the situation is that its a combination of a small amount of stanchion spinning and a small amount of individual leg compression that gives USD forks there inherent twisting issue. Having a through axle is obviously helping the situation, but it doesn't solve the stanchion twisting issue completely. When enough force is applied, its still going to give way and give that little bit of flex that USD fork are known for. Axles are also only as stiff as the mounting system used allows. In the motocross industry, they use bigger axles among other things to solve the flexing issue. Manitou uses to shape of the axle to make the stiffest(so far) USD fork available.


    The article speculates that only the top part of the stanchion is keyed, which would solve the seal issue. It also talks about how the stanchion being keyed(which would be the first of its kind) would solve most of the flexing issues. As of now its all just speculation though. Lets hope they produce it so we can learn more about what they did.
  • 09-02-2012
    Warp
    Quote:

    Originally Posted by mullen119 View Post
    Manitou uses to shape of the axle to make the stiffest(so far) USD fork available.

    Not only that, their axle is pretty thick (and relatively heavy). More thickness to resist twisting.
  • 09-02-2012
    t0pcat
    upside down forks are great till the seals start to leak and all the fluid runs out! when they need to be rebuilt there is not much choice!
  • 09-02-2012
    mullen119
    Quote:

    Originally Posted by t0pcat View Post
    upside down forks are great till the seals start to leak and all the fluid runs out! when they need to be rebuilt there is not much choice!

    True. But most dampers are cartridge based now, so you don't have to worry about loosing damping oil. And if a fork is leaking, it should be rebuilt regardless of orientation.
  • 09-05-2012
    mattsavage
    Quote:

    Originally Posted by Jon Richard View Post
    Isn't Paul Turner of Maverick Bikes now in league with X-Fusion? I love my DUC32 forks for trail duty.

    And Maverick's all had proprietary hubs as well...

    "Its long been said that to make a bicycle USD fork stiff enough(twisting wise), for larger riders and extremely aggressive riders, a larger diameter axle would be required... At this point, nobody wants to make a 25mm axled fork that comes with a hub. They dont feel the market is big enough to have the inconvenience." -Mullen119
  • 09-05-2012
    Shark
    As long as they stay with a hub that a hope pro can convert to, it's all good :)

    I would like to know if this fork fits a 4" fat tire....they were being tight lipped & won't tell me on e-mail....wish someone had a measuring tape lol. I know it's only a prototype right now, but dammit tell me how wide it is!
  • 09-05-2012
    Jon Richard
    Quote:

    Originally Posted by mattsavage View Post
    And Maverick's all had proprietary hubs as well...

    "Its long been said that to make a bicycle USD fork stiff enough(twisting wise), for larger riders and extremely aggressive riders, a larger diameter axle would be required... At this point, nobody wants to make a 25mm axled fork that comes with a hub. They dont feel the market is big enough to have the inconvenience." -Mullen119

    Well, even with the 24mm axle on my DUC there is a good amount of twist, but as stated above the mounting system plays a key roll.

    I think it will take more than a large axle alone to deal with independent stanchion rotation and telescopic movement to mitigate twisting. Thatís what makes this new effort intriguing.

    If keyed stanchions combined with a 20mm thru axle get the job done it would be great, otherwise the day may come when a new front axle standard hits the scene if stiff, long travel USD forks are to become a reality.
  • 12-15-2012
    'size


    https://www.facebook.com/photo.php?f...5018965&type=1

    "What are you riding this winter? #progression #xfusion #USD #shredsled #prototype #firstlook #ridemore"
  • 12-15-2012
    Mountain Cycle Shawn
    Wow, maybe it's really going to happen!
  • 12-15-2012
    David C
    Look good. I'd be interested to see some videos too.
  • 12-15-2012
    eurospek
    Was just coming here to post that Ibis picture. :D
  • 12-16-2012
    mullen119
    Please make it to production. It looks so sweet.
  • 12-16-2012
    Warp
    Quote:

    Originally Posted by mullen119 View Post
    Please make it to production. It looks so sweet.

    Yeah!

    The icing on the cake is the top of the line damper. It uses the HLR.
  • 12-16-2012
    Fix the Spade
    Quote:

    Originally Posted by Warp View Post
    Yeah!

    The icing on the cake is the top of the line damper. It uses the HLR.

    Even with the RL damper I'd have one, pre-set compression is something X-Fusion have nailed that others seem to struggle with tremendously (Hello Fox CTD).

    Anyway, that picture's made me go all weak at the knees...
  • 12-16-2012
    J:
    HLR and it's black, want, now
  • 12-16-2012
    Mountain Cycle Shawn
    Is it me, or do the legs look a little on the thin side?