Review: Intend Infinity Dual-Crown USD Fork
Intend Bicycle Components is one of the smallest suspension and component companies in the world, so it's understandable if the name isn't immediately familiar. The company, which is essentially a one-man operation, is headed up by Cornelius Kapfinger, an engineer who formerly worked with Trickstuff, the German brand best known for their beautifully machined, uber-expensive brakes. He's since branched out on his own, and now produces cranks, stems, disc rotors, and suspension components, like the Intend Infinity upside-down fork that's reviewed here.
Inverted, or upside-down (USD) suspension forks aren't a new development in the mountain bike world, but despite an ever-growing list of valiant attempts, they haven't been able to surpass the popularity of the much-more common right-side-up design. That doesn't stop companies from trying to crack the code, and Cornelius has tossed all of his engineering know-how at the Infinity to try and make his mark in the suspension world.
Inverted, or upside-down (USD) suspension forks aren't a new development in the mountain bike world, but despite an ever-growing list of valiant attempts, they haven't been able to surpass the popularity of the much-more common right-side-up design. That doesn't stop companies from trying to crack the code, and Cornelius has tossed all of his engineering know-how at the Infinity to try and make his mark in the suspension world.
Intend Infinity Details
• Intended use: DH
• Wheel size: 29", 27.5" or 26"
• Air-sprung
• Travel: Up to 215mm
• 20x110mm steel through-axle
• Adjustable rebound and low-speed compression
• Colors: blue or black
• Weight: 2,510 g / 5.5 lb (29")
• Price: €2,049
• 3 month delivery time
• www.intend-bc.com
• Intended use: DH
• Wheel size: 29", 27.5" or 26"
• Air-sprung
• Travel: Up to 215mm
• 20x110mm steel through-axle
• Adjustable rebound and low-speed compression
• Colors: blue or black
• Weight: 2,510 g / 5.5 lb (29")
• Price: €2,049
• 3 month delivery time
• www.intend-bc.com
The Infinity is priced at 2,049 Euro, but be prepared to wait up to 3 months for delivery – each fork is hand-assembled after an order is submitted. For riders in Canada and the US, you're out of luck, unless you're planning a European vacation – due to insurance reasons Intend doesn't ship to North America.
Design Details
The Infinity's air pressure is adjusted via a Schrader valve on the top of the left leg, which is the case with nearly every air-sprung fork on the market. The amount of end-stroke ramp-up can be adjusted by removing the top cap by using a cassette tool and screwing on a plastic spacer, or oil can be added to accomplish the same result. According to Intend, the Infinity's negative air spring volume is larger than most forks on the market in order to create a sensitive beginning stroke with plenty of mid-stroke support.
Rebound is adjusted on the top of the right leg. On my test fork, the rebound knob was 3D printed, and there weren't any clicks to help keep track of the position, which is a little inconvenient. The low-speed compression knob on the bottom of the same leg does have countable clicks, though, 14 of them to be exact.
Air pressure is adjusted on the left side, and rebound on the right.
Low-speed compression is adjusted on the bottom of the right leg.
The damper uses a semi-open bath design – a smaller diameter tube that's inside the stanchion is filled with oil, and the bottom of that tube is submerged in oil. The compression damper is located in that oil bath, but if you feel like tinkering with the compression shim stack all you need to do is turn the fork upside down and it can easily be removed from the bottom of the leg without any oil loss.
On the topic of oil, the Infinity uses 2.5W Danico Biotech Race Shok oil, which is produced from German grown sunflowers. I feel like Intend should include a sticker that says, “This fork runs on sunflower oil.”
Installation
I installed the Infinity on a Kona Operator 29 that was in for testing (look for that review soon). Without any steerer tube to cut, it was a simple procedure to get it installed and ready to go. The brake line routing is a little rudimentary, and it's important to make sure that it's done correctly, otherwise there's the risk of the brake line getting pushed into the wheel when the fork compresses. I'd say there's definitely room for refinement in this area – zip-ties and plastic cable guides seem out of place on a high-end fork.
On the Trail
All of my time on the Infinity was spent at the Whistler Bike Park, which is the ideal location to rack up a serious amount of vertical in a relatively short amount of time. Set-up was straightforward, and I ended up with 100 psi of air pressure for my 160 lb weight, with 7-clicks of low-speed compression and the rebound set according to my preference. The amount of range for the rebound and LSC isn't crazy – you can't make the fork return as slow as molasses, or feel like it's fully locked out – but it's reasonable, and I'd imagine that most riders would be able to find the sweet spot within the available settings.
The overall feel of the fork is one of controlled plushness – the travel feels bottomless, with just enough ramp-up at the end of the stroke to avoid any harshness. My hands welcomed the Infinity's trail-smoothing abilities, especially on high-speed, brake bumped filled straightaways. There was plenty of fore/aft stiffness on those straightaways as well, and the fork took whatever I plowed it through in stride, as long as I hit those obstacles head-on.
The downside to the Infinity's design, and the same issue that's plagued nearly every mountain bike fork that's gone down this route, is the lack of torsional stiffness. On sections of trail that required a lot of front end movement, that lack of stiffness became quite apparent. At times it felt as if there was a delay between when I turned the handlebar and when the front wheel moved, a sensation that was even more noticeable if there was a sequence of multiple quick turns. That's when it felt like I really had to use extra effort to get the front wheel to track where I wanted it to – it was like driving a car without power steering.
The flex felt detrimental when the trails were hardpacked and running fast, but there was one extra rainy day where the Infinity's potential shone through. The roots were slick and the mud was deep, but I found that if I relaxed and let the fork find its way there was much more traction available than I'd anticipated. I still had a few moments where it felt like the fork got hung up when I tried to force a direction change, but it was in those wet, slippery conditions, times where finesse is key, that the fork felt best.
How Does It Compare?
The last upside down DH fork that I tested was 5 years ago, on a bike with 26" wheels, so I can't draw any direct comparisons between the Intend and another USD fork. However, I can compare it to the RockShox Boxxer World Cup whose spot it temporarily took. The Infinity is a little lighter than the Boxxer, but I can't say that I noticed that out on the trail. What I did notice was how easy it was to initiate the travel on the Infinity - its beginning stroke was more supple than the Boxxer's, and overall it felt more linear and 'plush', for lack of a better term, while the Boxxer was more supportive in the mid-stroke. Of course, that trait can be tuned to some extent on both forks with volume spacers.
The Boxxer does have a wider range of adjustments, along with externally adjustable high-speed compression, which makes it easier to adapt the fork to suit a track or personal preference. And then there's the whole stiffness side of the equation, which the Boxxer wins handily - the difference between it and the Infinity was very noticeable.
Durability
The Infinity has seen a mix of dry and dusty days and some absolutely sloppy ones, and it's remained smooth throughout all of it. However, those muddy laps did begin to take a toll on some of the anodizing - the brake line rubbed through the blue in a few sections. Installing some clear protective tape ahead of time would be the best tactic to avoid this issue. How about those unprotected stanchions? They've survived without a scratch.
Pros
+ Plush and smooth travel
+ Light weight for a dual crown fork
+ You'll stand out from the crowd
Cons
- Lack of torsional stiffness
- No built-in cable guides
- Expensive, not available in North America
Pinkbike's Take
 | While the Infinity isn't the way to go if stiffness is high on the priority list, the damper does work very well, and the overall ride feel is quite comfortable. Creating a suspension fork from scratch is no easy task, and this fork is a valiant effort from a very tiny company. It'll be interesting to see what Mr. Kapfinger comes up with next. |
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carverbikes.com/parts/accessories/carbon-stanchion-guards
i use same guards on my German:A carbon Flame forck
gnartec.com
They already have a range of stanchion guards that are pretty simply yet clever
(from website)
"No, my experience with that not covered lowers is: no problems at all. If you take "normal" care about your fork, there will not be more scratches on the lowers than on the uppers of a normal fork (there are no guards either and nobody gives a shit). If you are scared, there is a way: don't buy it
On a normal fork the contact points between left and right side are hub/axle, arch of the lowers, and the crown.
On an inverted fork you can not do better than hub/axle and crown. If you add the guard, it will look like you have an arch in the middle( like on a normal fork) , but as it is attached to the axle level, it will not do much.
Also, my dirtbike has an inverted fork... And guards. Seems like an easy thing to design with a low weight penalty, why wouldn't you add them?
1) I have no scratches on my stanchions. If you crash into a pile of rocks damage can always happen no matter if stanchions are further up or down on the fork and for the rest of that days when you don't try to get a part in the next episode of the Fridayfails just take care of your stuff and everything will be fine.
2) measured stiffness values are an absolutely irrelevant number German Bike magazines cam up with so they can be German and compare something. Matter of fact everything needs to flex. An absolute stiff fork would be an nightmare to ride.
An upside down fork flexes different than a conventional mountain bike fork and this is what people notice when they use a fork like this for the first time. better or worse? try t out!
By reversing the fork flex in certain directions like back and forth becomes much better where as torsion becomes a bit softer. Its a trade off. A certain amount Torsional flex is actually nice for a smooth controlled ride.
Back in the day I had a dorado and people who never rode the fork or anything similar had the same complaints which honestly is ridicules. Don't judge stuff you have never experienced.
finally, cause I know its going to come up, no I am not I dentist, I wholeheartedly hate going to the dentist...
1st World country: our stuff is best.
2nd world country: other's stuff is best.
www.peugeot.co.uk/about-us/awards/cars-awards
www.pinkbike.com/photo/17255346
BUT! (just to bust your balls a bit if i may lol) you pug is not a pug, its based on a Mitsubishi ASX, which is a great car btw..
If you ask me now "what is just simply the best car in the world hands down", there is really only one answer: Lexus if you have money, Mazda if you dont (not that they are cheap though lol). I used to put Toyota and Honda in that list, but there is one simple reason why i dont anymore (at least for the time being): both brands are switching their models policy from local to global, and they are running over bumps because of this. Now, toyota is handling the situation better than Honda (as expected, since they have more experience with world-market platforms through Lexus) so they dont have quality issues, they have other issues that dont affect customers really. Honda though, did one major mistake imo, they went both feet in at the same time with new technologies (mainly mass produced turbo engines) AND a world-market-platform policy. Thats why more than ever you hear about ppl having trouble with their Hondas lately, something that used to be a tabu in the near past. Honorable and well deserved mentions def go to Suzuki, Dacia/Renault. These guys have been putting out some SERIOUSLY good vehicles lately, their improvements on quality, attention to detail, production plants and customer service have been nothing short of amazing in the past 5-10years..
Two things need to be added ti the equation though: 1. every brand has good and bad cars, nothing is perfect, not even a Lexus. Even though thats the brand imo that comes darn close near perfection...and 2. Time has shown me that this "list" changes all the time. New techs, production and trends shift things around more drastically then ppl realize. And thats my main problem with german brands: they used to concentrate on building cars, now they are concentrating on building trends. Thats why there is a new german model almost on a daily basis and new "gimmicks" from them every day. Thats why my friend that works for AMG works 12hrs a day fixing them, but at the same time a Smart is a Twingo as much as a Citan is a Kangoo. And guess what, both of the "renaulcedez" are (again, at the moment) the ones with the least amount of warranty issues...but trust bro, i could go on with this for days...but i'll shut up now and get back to work LOL
Thanks for the sidetracked discussion, I appreciate it.
I would argue that the manufactureres know very well what the magazines (and their readers) want and value, so they make product that caters to the market.
Example: For many years German riders didn't care much for geometry but would buy the bike with the best components for the price. And Canyon/Radon/etc. excel at that metric and therefore won every comparison test.
I have worked in the motor industry for 29 years and currently I'm an electrical engineer for a manufacturer (previously BMW 13 years - master technician)
I think you should become a tabloid commentator in the motoring section with your in-depth knowledge of the motor industry (No offence intended pperini)
Personally....I could tell you about the department I work in and what they do quite confidently, I could also tell you how to diagnose and fix BMW's (past models that I worked on, up to 2015) .....what I couldn't do confidently is tell you the facts about what is the best car on the road, which ones to avoid and why to avoid them and crucially which country makes the best cars (I could read a lot of the stuff in the press from industry analysts BUT I wouldn't know anything of actual substance)
So really guys when somebody offers an opinion, it's just that...an opinion. My opinion is that German motor manufacturers make damn good cars and motorcycles compared with what I have owned and worked on in the past 29 years
Cracking looking fork by the way (wonder how much mileage accumulation / durability testing a one man band could do though compared with the big players)
Tschuss
www.jdpower.com/business/press-releases/2019-uk-vehicle-dependability-study-0
>> Of COURSE there are many, many great german cars
What does it even mean?
It is obvious that there are unreasonable politics in many, if not all, corporations. It is also obvious that every car is a different project with different constraints and requirements and different people working on them. So I still have no idea what your point was, since usually if one blames media for jerking someone off, reasonable arguments are expected. In this particular case, I find it impressive that one man made a product that is on par with competition on multiple parameters.
I already did it:
>> we dont make decent cars since the early 90s
>> Of COURSE there are many, many great german cars
Who precisely asked for this opinion? www.pinkbike.com/news/review-intend-infinity-dual-crown-usd-fork.html#cid2323689
I was the one who has asked for your opinion when I asked whether I understood correctly that you use reliability as the only characteristic to define whether a car is "good" or "bad", but never got an answer. Nothing on internet "insults" me, I was just hoping that this time maybe I will read constructive arguments instead of "it's bad and it's my opinion". Can you please share a link to some sort of a material where a car magazine article is constructively criticized? I would really love to read it.
"we dont make decent cars since the early 90s". Now, this is my opinion. This is me, expressing a personal opinion, that cars since that era arent up to my personal standards anymore.
"of course there are great german cars". This, now this is NOT an opinion, this is a fact. Regardless of how i feel about newer german cars. Some of them are very reliable, comfortable, fast, spacious, etc. Some of those (and more) attributes is what contributes for what we call a "good car". And again! Thats a FACT! Regadless of how i feel about it.
Why isnt this a contradiction? Simple, its called being an adult and being able to admit to the world that facts OVERRULE your personal opinions. In other words, not only because i THINK all cars are no good anymore, doesnt mean that they actually arent, and i RECOGNIZE and admit that FACT. Thats why it is NOT contradictory.
Who precisely asked for my opinion? Mr. "whambat", when he said: "in your opinion".
To address your point about reliability: yes, i highly (but not exclusively) rate vehicles high or low judged on reliability. Why? Two main reasons. First, a vehicle is first and foremost a transportation mean, and if the vehicle cannot function its primary purpose because it constantly breaks down all the time, then its value start to decrease in relation to its primary function. Not to mention unnecessary costs etc. Second: because i worked for a very long time as a quality manager when i was an engineer/test-driver, and as i mentioned, such a job can really change your perspective on things.
Now, do i judge a Lotus Elise the same way i judge a Corolla? Of course not. You dont buy an Elise for reliability, comfort, space, luxury, even speed (cuz really they arent even that fast). You buy an Elise because it is FUN. In my opinion.
Now, "fun" became the main function of the vehicle. You did not buy an Elise to go from A to B. So if this vehicle starts to give you trouble, it is up to YOU to decide if this trouble is worth its VALUE. And that is something that everyone has to decide for themselves. Thats why i keep on banging the argument that everything i said is purely based on opinions and experiences. Values differs from people to people. So ones opinions might not match others values.
Obviously i cannot share any documents or links with you because i used to work with highly secret prototype vehicles, and ive probably signed more papers then i can remember on "confidentiality terms". So the internet is most definitely the LAST place i would publish the things that i know.
But then again, do the things that i know have to affect anyones life? Of course not. As i already said, everything is relative to your values. Just as much as i saw many BMW fans (for example; co-workers) that would crawl under their cars on the hoist every single weekend to fix something that was broke and still praise BMW to be the best brand out there. Again, its a VALUE thing. They value other things beside reliability. And thats fine, unless one is extremly stubborn and obtuse. Would i buy a new German car today and if yes what would it be? Well, i wouldnt buy one out of the blue because for me personally their prices outweights their value, BUT, if i "had" to buy one, funny enough it would be a BMW M2. Why? because that car IMO gathers the essence of everything that i like so much about old BMWs. Regardless of how "good or bad" it is, my personal value to this particular vehicle is based on a subjective sentimental fundament, Therefore overruling any other downside that the vehicle might present when judged by other terms.
Yeah I agree with you totally reliability isn’t the only standard. The UK hasn’t made a reliable car since the horse but it’s made plenty of great ones!
Honestly, I have one of his forks, its just a good working no BS product which is really unique these days on any product.
Its unfair to compare him it to "Auto Motor und Sport" making the Audi or VW win every shoot out even though the lack handling or safety features or whatever, by simply giving them maximum pointing for glove box ergonomics...
>> Obviously i cannot share any documents or links with you because i used to work with highly secret prototype vehicles, and ive probably signed more papers then i can remember on "confidentiality terms".
1) you tested prototype vehicles, but you voice opinions on mass-produced vehicles, which makes no sense. There is a reason for a big red button in a prototype car;
2) you have probably not read those papers, since they are not that restrictive. Quality engineer usually has no idea about intellectual property behind the product and you can easily say something like "once upon a time I found a critical problem in a suspension linkage and the product went into production without a fix", since this information does not link you to a particular company/product. If you really "worked very long time as a quality manager", most of the NDAs have probably expired either way, since the concepts behind the product have been made publicly available until today;
3) do you have any information about the work of quality engineers in the companies that, as you have stated, make "good" cars?
4) I asked for links to any material that, for example, takes an allegedly biased magazine article and picks it apart with constructive criticism, not necessarily written by you personally.
1) no pro types usually derive from existing platforms in group, therefore some flaws which designers feel aren’t flaws carry over
2)spot on, quality engineers look at process control, not fit and functional performance this is down to engineering. They don’t fix components they look at cause and effect
3) see above- I worked at Bentley, the perfect mix of VW strategies mixed with blokes that smile roll ups and love a hammer
4)there are plenty of consumer reviews that disagree with mass German brand arse licking, look at any decent shootout in the comments
There not war and peace but facts
1) Designers work under constraints and have a set of requirements. What quality department might treat as a flaw is oftentimes just an expected behavior. Do you have any examples of carryover flaws of any platforms?
2) If it's spot on, please feel free to share any info, I'd love to learn more on the topic.
3) pperini did not name Bentley as a "good" car, what is that all about?
4) Do you care to share any links? I never saw drastic differences between german and non-german press, we're not talking about consumer reviews here, since it's a whole different story.
1) absolutely , I work in braking. The amount of flaws I see in rotor development alone that OEM’s carry over because “it’s the way they’ve always done it” is shocking. Coating on Lotus discs is sacrificial and applied at 3 microns, we them receive complaints that the discs rust!
2) Quality engineers are there to provide assurance that the product meets the customer and engineering specifications in the most economical manner, they do not question really the performance of the product. They may in advanced performance quality planning meetings when the process / design failure mode effect analysis is carried out (google APQP and FMEA) bit as a large they are there to assure product performance against engineering specifics / customer specific requirements
3) Bentley are basically VW carry over , I could mention other OEM’s I’ve worked with , Mitsubishi, Audi, BMW, Jaguar etc, they ALL use the same core tools and have to as it’s a requirement of the automotive task force specification IATF16949 which is the benchmark for automotive standards
4)I’ve seen various on Auto Express shootouts, I’ll have a dig
Since all the manufacturers use +/- the same tools and processes, I do not see an argument for german cars being inherently worse and german media being overly biased. Besides that, if reliability is the primary metric of how good a car is, how is a journalist supposed to estimate it if he/she has access to a car only for a few hours/days? I have read the used market guides in those same german magazines and they explicitly mention most of the problems the consumers report on forums etc.
Coming back to this article, we (I at least) have no idea what the QM process at RockShox looks like, maybe their engineers roll their eyes when they read PB reviews too, I have all the reasons to believe that's the way it is after owning RS. The only way forward for me is supporting small engineering efforts like Intend, which have a decent product and extremely good customer service. I was also curious why so many germans are professionally unhappy with anything german (I am not german and my location on PB was picked randomly :-) ).
Cheers
I bet it rides extremely good
so , this "smouthness" help keep control of the motorcycle , absorb heavy side impact , and keep traction. that's why they use steering damper and USD fork , stiffer is not always better , especially when going fast with big side forces on the front wheel.
An MTB is a completely different thing to a moto though, for a start its about 400lbs heavier so they can build a fork in a mich more substantial manner so a desired stiffness is probably not so hard to achieve there.
I know the fox 40 is a conventional fork so no direct comparison but it has a staction diameter about the same size as a modern yamaha R1....
www.pinkbike.com/news/fox-dh-fork-inverted-prototype-2012.html
They tried many different axle sizes and arrangements, but still couldn't get it torsionally stiff enough.
The old Curnutt inverted fork that came on the Foes Mono had a 30mm thru-axle, and was stiff enough that no one complained, but it also weighed over 10 pounds.
www.bikeradar.com/reviews/components/bike-frames/mountain-bike-frames/foes-racing-21-dhs-mono-review
The main flaw of the leftys were their garbage damping. They had 0 high speed compression and the low speed compression always felt funny, like it was super supple off the top but then would hit this wall of peanut butter, as if it had only two inches of travel, and then once you passed that threshold it just blew through all its travel, and had way bad brake dive. Their rebound was rubbish too. The chasis, however, was perfect. If they resurrected a 150 or 160mm 29er with their new, updated damper and a modern offset, it would be at the top of my wish list!
My 2cents on this subject:
I have limited MX experience, but, in general, when riding MX you should either be on the gas or on the brakes. An MX track is always flat (as in starts and finishes at the same height) and the whole track is 'important'. When you are on the brakes and/or hitting bumps in a straight line, the USD design offers a much stiffer chassis and much less binding/stiction under these loads.
When you are on the gas, acceleration makes the front wheel is light (watch pro-riders and their front wheel is barely on the ground) and the torsional flex helps the lightly-weighted front wheel track well especially in ruts and when trying to keep the front wheel carving a nice turn while on the gas – if the fork was super stiff torsionally it would track badly and bounce off the terrain easily.
On a mountain bike, you ride in different ways, but descending is the main bulk of 'important' riding, we often start and finish at the same point, but going uphill doesn't matter much to the type of fork. Riding on flat ground starts to create some problems, but going downhill is where it gets complicated. Descending performance is the most noticeable/important to riders, which takes in many factors like braking/cornering/difficult terrain/pumping etc, doing anything you can to keep your front wheel where you want it and heading down the trail.
I rode the Intend Edge last year, and riding straight into square-edged bumps on or off the brakes shows a completely different level of stiction-free and smooth performance from the USD design than any other conventional fork available. Also if you are off the brakes, and going through rocks/roots/off-camber it also offers a different level of tracking and performance - especially in the wet.
Like I said above, the problems start when descending/braking/difficult terrain are all happening at once, all of your mass is moving forward on to the front wheel, this is also when your brain starts to get the most scared and you have the hardest time gauging what is going on. The USD has a much more vague feeling when all this is happening, but the torsional flex isn't the only issue. I was told by a certain engineer who worked on the USD forks for a major company (they probably don't want to be named), and it makes sense when thinking about it on the trail – the issue comes from the lower legs moving at a different rate to each other – this means the wheel does not go through its travel vertically but in more of an 'S' or wavy line. If there was a way to fix both lower legs so that they travel at the same rate (like the DVO solution) then the USD fork would be more suitable for MTB riding overall*
*I think
I service my fork myself and when I have those lowers in my hands I'm always impessed by the lightness. The weight is very close to the stanchions'.
I'd be curious to do the math but I don't think there is a substantial unsprung weight reduction on inverted (mtb) forks. Most of the unsprung weight comes from the wheel anyway, shaving a few grams on the unsprung part of the fork probably doesn't do much.
I think.
Nah, it's not as easy as that. Riding MXs bikes quick is way more than that. You need to balance between beeing on the gas and braking it in for stability. Also tracks really vary in height, and due to the nature of the sport you put much more stress on the suspension components (eg. heat etc.) That's why you will feel a bad suspension-setup way quicker on a motobike than on the mtb.
But the weight doesnt matter that much on the bike, sure there is air-forks like the Showas or AER WP's but it's a small difference and many people opt for A-Kit or 3rd party suspension when racing anyway.
As you said, you really need the flex in the front end to keep it tracking in ruts, while beeing beefy enough to hold up 100ft hucks to flat on full throttle.
Moto forks are not torsionally stiff, either, yet nobody in moto is looking to flip the fork "right side" up because we've all decided in that sport the flex is exactly what we need. These are machines that weigh far more than a mountain bike, often traveling at higher speeds and doing crazier things.
We need to open our minds, and we need to be more objective when testing product like this. Spend more time on it, put some laps in where you are comparing it to a baseline like the 49 - and let the times (and arm fatigue) speak for themselves.
...plus, wheel selection, wheel size etc all has to be a part of this!
Differences between USD and non-USD (for dual crown forks)are:
- longer bushing overlap on USD forks, so less frictions. Between 30% more and twice as much bushing overlap.
- No arch so more flex, and it can be more than twice "flexy", and it has some "degressive stiffness" so more difference on tight corners. It can be a real issue depending on your riding style and your favourite tracks.
-higher diameter at the clamp, so if designed well, you can partially offset the flex issue.
There is a smaller difference:
oil has to go over the stanchion to access the seals, so lubrification has to be managed properly.
And there is no real difference in "unsprung weight", and if it has a marginal one, non-usd forks does have lighters lowers than usd have.
People keep saying I can't compare mountain bike and moto, bla bla bla.
Fact is, if we would have followed the path moto laid out way back when, we would have had modern geo, correct trail numbers, and every suspension layout would have been rising rate. My Transition Sentinel has more in common with respect to handling and suspension with my KTM 300 XC than it does any bike I owned over a decade prior.
So yeah, keep "believing" USD c an't work for mountain bike. I think its a perception problem, not a performance problem.
Try something...
Take your front wheel and brace it against a wall or similar. Cycle the fork. Feels good huh? Now apply a little bit of torsional load to the bar. Tell me how good that fork feels now...
Sure, its pretty dang stiff! But this stiffness comes at a cost, not only will it be more prone to deflect but the bushings will bind on the stanctions.
With more overlap, and an USD design, you'll get more flex, but you'll also allow the suspension to work in these lateral load events.
I'd 100% go to an USD fork that was flexy, and I think the market will one day see the light - too.
This isn't even debated in moto. And for good reason...
If an inverted design is superior, then why didn't the Dorado sell better? Why won't x fusion sell their Revel outside of Asia? Why did Gee, Gwin, and Fox give up on their inverted prototype?
www.pinkbike.com/news/fox-dh-fork-inverted-prototype-2012.html
The reason inverted hasn't caught on is the same reason DH bikes "couldn't turn" with 64 degree head tube angles back in 2002, or "29" wheels sucked at cornering" in 2009 or "51mm offset cornered better in 2011 (for 29)". ***PERCEPTION***
We all have far more cognitive bias than you want to admit. Its not just the consumers that buy into all this, pro riders, too, have biases. If something feels different they may say "no" even if it is indeed better.
Sometimes you have to reframe 'right' before you can determine if it is in fact better. Sometimes you have to change your riding style, something pros may not be willing to do. Sometimes you have to reframe the problem - such as "what kind of flex is good, what kind is bad".
Finally, the Dorado didn't sell because Answer has been in the shitter for over a decade. They don't support racers. They don't support races. They are just off the back when it comes to overall product experience compared to Fox/RS.
I'm not saying all forks will be USD, but I am saying for enduro I'd 100% expect a dual crown USD fork to come to fruition in the next few years...and it will be better.
USD forks is actually something I've put a ton of thought into. In order to torsionally stiffen them up, you need either keyways like the Revel (that doesn't sound like it worked) or some sort of bearings like the Lefty on at least one leg (which requires twin crowns, now too heavy for anything but DH) or a scissor linkage like what airplanes use (too ugly for fickle cyclists).
Nico ran an USD fork, and often detensioned his front wheel a bit, too, for more grip. He was looking for a balance between flex and stiffness. Go ride a Fox 40 with some old school enves and tell me how awesome it really works. Precise? Yes. Faster? No way.
This "engineered flex" is common in a number of other off road sports, where engineers are trying to get something to give in a certain way for the best possible handling. Hell, even Yeti went through pretty crazy lengths to try and get their new SBs to flex more than their old bikes.
Dirt bikes do not have keyways or roller bearings. They run on bushings, just like mountain bike fork.
Here is how I think you make it work...
1) Go back to the drawing board with respect to crown design. We are going to need crowns that have more clamping surface area than most being used or that have been tested.
2) Make sure you have extensive bushing overlap. This is key.
3) Accept that there will be a weight penalty (this is likely the reason we haven't seen it yet). I'd guess it will be around 300grams in a best case scenerio.
4) Stop confusing steering with cornering. They are different. An USD fork will corner awesome when done right, but it will be more flex prone when "steering".
5) In a shorter travel application (170-180mm) it'll be easier to achieve acceptable overlap without undue weight.
6) You could use the fork slider protectors to make some kind of an arch to give a tiny bit more stiffness (this could be part of the engineering)
forums.mtbr.com/attachments/maverick/34722d1097682539-29-maverick-duc-32-fork-ml7-frame-duc32_600.jpg
That is an interesting tidbit you shared about the Revel. Real world ride reports are scarce for that thing, and I had always wondered about how the keyways avoid stiction (and wear). From what you're saying, it sounds like they don't.
And as Mullen also said, Manitou has been owned by Hayes for many years.
Anyone have any inside intel on why the Giant team, who presumably had their pick of the litter, chose to go that route? Weight? Torsional stiffness? Habit?
Any one @DVO care to comment? We think your forks, both USD and right side up are great, so please give an unvarnished perspective rather than a marketing spun one. ;-)
Still don’t understand where the whole stiffness obsession thing came from either. I came to mtb from an off-road moto background and still prefer the chassis feel of some of the older non super huge stantioned forks. (The new dampers are the tits though).
Moto axles aren't that much crazier than a 20mm mountain bike variant, especially considering the machine in question.
Mountain biking has long tried the moto axle attachment method. It works. And it should be further utilized for perfectly straight forks, but it won't solve the stiffness "problem".
GO up to a moto. Put the wheel between your legs and twist. Guess what? They are "flexy"! But nobody cares, because its a problem that exists in a vacuum in that world.
I had assumed it was for ease of manufacture, but perhaps it was for structural reasons.
Offset doesn't change stiffness. And wheel contact point is never in the alignement of fork's legs, so even "in line" dropouts have an "offset" regarding forces.
Some forks does have "inline dropouts" because there uppers are so big, they can effect the steering angle. So you have two ways of solving the issue:
- wider crown
- more offset at the crown, thus less offset at the dropouts.
Second, the term "stiffness" is very broad, and there are different sorts of it. USD forks for MTB indeed ARE stiffer than traditional right side up forks...in a fore-aft direction. On the other hand, torsionally (like if you held the wheel between your knees and twist the bars), they are less stiff, and similarly they are less resistant to independent leg compression, again due to a lack of an arch joining the lowers.
Is it possible that when you have heard references to USD being stiffer in moto, they were talking about fore/aft stiffness, and not the other sorts?
www.mtbr.com/product/older-categories-bikes/2005-front-shocks/maverick/duc-32.html
Loved them at the time but had to own 2 of them since I was sending them back to the factory every 2-3 mos.
www.crconception.com/FORE-SC
www.pinkbike.com/photo/17023200
www.pinkbike.com/photo/16973912
www.pinkbike.com/photo/16973913
It would have received a better review ????????????
no stanchion diameter? wtf?
Oh yeah. Everyone...
A DH fork that rides like a noodle.
Moreover reading how arrogant this company is "we made the best of this and that"....
It looks like a "just out of school" project to me.
Seriously though, stop making everything blue, doesn't matter how good the fork is, i will never put a f*cking bright blue fork on my stealth black bike. Stand out by being better, not with a shit colour...
www.mtbr.com/product/older-categories-bikes/2005-front-shocks/maverick/duc-32.html