The Explainer: What's the Deal with Linkage Forks?
THE EXPLAINER
What's the Deal with Linkage Forks?
What's the Deal with Linkage Forks?
Trust might have broken the internet and divided opinions when they announced their Dave Weagle-developed Message linkage fork a few months back, but they're hardly the first to the weird fork party. In fact, linkage front-ends have been around much longer than the now-dialed telescoping forks we get to use today, with relatively primitive examples showing up as far back as the late 1800s.
From there, these funny looking contraptions have been used on the front of everything from folding bicycles to Grand Prix racing motorbikes and all that's between. But do you know where they haven't shown up? On the front of many people's mountain bikes. Despite a lot of attention and excitement, linkage forks have largely been a commercial flop, with only Girvin (aka Proflex) and AMP enjoying some brief success when the time was right and most things sucked anyway.
And then poof, aside from a few low-volume, boutique manufacturers that probably sell a couple of forks every year, the Erector Sets were mostly gone from the front of our bikes and we really only had telescoping models to choose from.
And then poof, aside from a few low-volume, boutique manufacturers that probably sell a couple of forks every year, the Erector Sets were mostly gone from the front of our bikes and we really only had telescoping models to choose from.
Full-suspension with a linkage fork up front. It might not look safe, but this was state of the art back in 1891 when it was patented.
Not that that's a bad thing - when it comes to suspension, we've got it damn good these days - but it is a little... boring. I mean, isn't that freakshow below interesting?
AMP's minimalist design (left) was intended to be a lightweight cross-country fork that could compete against equally spindly 50-millimeter-stroke telescoping models from Manitou and RockShox. The Motion Ride fork (right) offers up to 170mm of travel via a carbon leaf spring.
Whyte's PRST-1 (left) from the early 2000s used a linkage fork that offered consistent trail but its appearance was, er, challenging to say the least. Structure Cycleworks' prototype also integrates the fork into the front triangle, making it a package deal or nothing.
Interesting or not, I seriously doubt that many of us would be okay with an expensive, unproven linkage fork with a non-existent track record. Or would we? After many years of the Big Two (RockShox and Fox) practically owning the high-end front-suspension market, there was a promising shake-up when the latest linkage fork arrived back in October with a lot of carbon fiber, a fancy thru-shaft damper, and a Dave Weagle. It turns out that we're all still interested in linkage forks - that was one of the most-read articles of 2018, and it has nearly six-hundred comments, many of which seem to be upbeat about the new challenger's prospects. That said, I think that success for Trust would look like a good number of forks sold and to have them perform well and reliably. The OE sales numbers that the Big Two can boast about are essentially untouchable for the foreseeable future, of course.
So it seems like a good as time as any to take a look at how linkage forks work, as well as why they might make sense and why they might not. Oh, and if they're so damn good, why aren't they on the front of all our bikes?
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So you need a way to stop the upper rotating in the lower, this is the reason for the NRBs, its a square tube in tube. Or triangle.
You did..... you did eat a cat.
www.youtube.com/watch?v=_WlRqcAQr2w
It's always fun to read and talk about a freak show, but when it comes time to drop $1K on a new fork it'll be a standard telescoping unit.
People can't stop looking at or talking about a train wreck either, but that doesn't mean anyone wants to pay to be involved in one.
Yeah, but if you want to drop $3K on new fork, where are you going to turn?
youtu.be/dalydWD30_I
Course how long did ENVE pull off the same trick?
www.pinkbike.com/photo/16931508
I'd pick up a:
Fox 36: $1000
ANNNDDDDDDDDDD.....
Front & rear Maxxis tires: $130
Enve Handlebars: $170
Fox X2: $650
New Helmet: $150
Local bike park pass: $400
Lunch for everyone at the bike shop: $100
____________
$2600.00
Come for a ride with us to see what all the fuss is about?
Mixed review: www.leelikesbikes.com/trust-message-fork-my-first-four-rides.html
Positive review: cyclingtips.com/2018/10/trust-performance-message-fork-review
Open condemnation: singletrackworld.com/2019/03/review-judgement-day-trust-message-multi-link-suspension-fork, singletrackworld.com/2019/02/trust-performance-suspension-linkage-fork-review
This says enough. Some journalists hate to disappoint sponsors or affiliates, but a few will tell the truth. Here more than a few are telling it how it is.
People seem to forget Newtons third law = for every action, there is an equal an opposite reaction. Just like with the rear anti squat setups, the more anti-squat you run, the less the bike bobs and more of your power gets put into the pedals. At the same time, it also stiffens the suspension when you are pedaling (because its actively forcing the wheel down which opposes its tendency to travel up in response to a bump) and creates pedal kickback, which when opposed by your legs also stiffens the suspension.
These linkage forks are no different. Sure, there is no brake dive. When you hit your front brake, you bracing against the handlebars to avoid flying forward causes your inertia to translate into a forward pitch moment, which would normally compress the traditional telescopic front fork. With these linkage forks, the linkage opposes that motion, which necessarily and absolutely stiffens the fork. So now, when you hit the front brake, your wheel just skips over rocks with less absorption and translates that force into your arms.
I'm not saying it's not possible by the way, just asking how.
In my mind, the distance between the axle and the bottom of the head tube affects the head angle. Shorten the distance and the head angle necessarily steepens. Since linkage forks or indeed any suspension forks get shorter when they compress, how can it be possible to not affect steering geometry?
So, that still leaves you with however many bearings there are left to fail, on top of the bushings, no?
I'm not anti linkage by any means, I'm just struggling to understand how they can be better apart from being able to adjust compression ratios.
If the linkage fork is designed correctly, the spring/damper will have pivots at either end of it that prevent it from experiencing those bending loads (can't transmit torque through a bearing that spins) and only expose it to linear compression/tension. So yeah that spring/damper will still have bushings, just like the shock in a linkage rear suspension, but they will be much less likely to fail and wear out due to off-axis loads.
I hope they make this product work, and can carve out a market for these that sticks around. Options are cool to have.
Side note: the overall second place finishers of both the men's masters and women's masters EWS series are on the Message this year and appear to like it quite a bit.
Wouldn't have to be tested I just want levy's internal rational and or logic (preferably about 2 beers and 10 donuts in)
With a linkage fork that has a backwards axle path means that the fork is moving backwards and up instead of flexing and binding as it moves out of the way of the bump.
All telescopic forks shorten the wheel base under braking and bump forces also. They also change the Trail as they compress. Which affects handling. Linkage forks can tune that out - be constant Trail.
I'm not an engineer.
So yes a conventional fork does shorten wheelbase when compressed but even at a 60 degree head angle (to take an extreme case) and a 160mm fork you will only get about 92mm reduction in wheelbase, and only 75 for 130mm travel where as the trust fork due to its proportionally larger rearward travel looks like it might have far more than that ?
Interesting point on the trail being maintained, on the one hand something remaining constant is easier to predict and control when your mind is busy g-ing out, but at the same time a larger trail slows down steering, which I like as a quality for when you are at full compression as generally at that point i would like me bike to be super stable and slow steering.
I am only a student, so can't claim to be an engineer either.
P.s what are your thoughts on the effect on braking?
Honestly the summary of linkage forks in the video is spot on. yeah they may be 5% 'better' in one given sphere, but they are 10% 'worse' in others. Stiction reduction Vs complexity of manufacture/maintenance. Anti Dive Vs additional cost.
They're an evolutionary dead end. Neanderthal man might have been better at cave painting than Homo Erectus, but that wasn't enough to ensure survival of the race.
lacemine29.blogspot.com/2018/12/trust-message-fork-review.html
singletrackworld.com/2019/03/review-judgement-day-trust-message-multi-link-suspension-fork
I’d try the Trust fork.
At three to four times the price of a comparable telescoping fork?
I’ll stick with a telescoping fork.
Honestly, I get that the Trust fork is special, lots of engineering and design went into the fork, just like a suspension frame, but quite frankly I’m not gonna spend 25-35% more on a mountain bike to get that fork.
Bring the price down to $1500 and set up some demos, then I’d consider it.
Out of interest, why would you like one if money were no object? On looks alone or do you 'trust' that the performance will be there because DW has is name on it?
See what I did there? Dingus.
Maybe you should catch up
I personally don't get the push back on all things new. I'm typically an early adopter of everything whether it be a new sport or new gear. I think it's sweet to have something odd and that the rest of the herd doesn't and I don't care at all if it's not considered "cool".
The trust fork is out of my budget but if all things were equal and it works as described I'd love to have one on one of my bikes.
Rear of the bike: "telescoping chain stays, or simple single pivot? luddites"
Of course front and rear at totally different situations with regards to wheel motion, but I have often wondered why, with all the investment and development of linkages at the back end, why no one really seems interested in chasing better kinematics up front.
Path of least resistance please - That means telescoping, because:
1. Technology is pretty dialed and seems to keep advancing (incrementally)
2. Widely available
3. Parts and service are widely available
4. Cost/benefit ratio
5. Likely easier to resell if that comes into play
I disagree about your comment about Fox/SRAM never making a linkage fork though, if it ever happens to gain momentum and the pricing comes down, they will be all over it. If there is a market for it and $ to be made, they would be silly not to.
The higher end of the line Honda Gold Wing line eliminated telescoping forks in 2018
The Trust is expensive...but look at the price of a carbon wheel set compared to aluminum ... 2x - 2.5x higher. If you are just buying hoops it's 3x - 4x the price of aluminum. There's no shortage of carbon wheels in most any riding environment with high praise being heaped on them...and over the years the "Dentists on Yeti's" bias has pretty much left us with respect to just about any carbon component.
So if value is perceived, they will show up.
I'd like to see them offered as an OEM option where the wholesale price can be reflected.
How close is the 29 160+ version?
PS The photoshop post of the Trust on the new Mount Vision is Awesome. Weagle Voss El Solitario Beast Mode -
WVESBM....way too kickass to be some sort of mundane TLA (three letter acronym). WVESLM is the Ludicrus Mode...Electric natch.
That's cold man, real cold
Made me do a proper office LOL!
Loving this new format, @mikelevy you're a natural at this.
Telescopic forks can have higher stiction, but it is a 1:1 system
In addition, the video clip shows flexion on the bottom of the steer tube(not the head tube). Makes me think how much of the flex it can take before it gives. My .5 cents. Thank you.
''So it seems like a good as time as any to take a look at how linkage forks work, as well as why they might make sense and why they might not. Oh, and if they're so damn good, why aren't they on the front of all our bikes?''
I'm new so maybe I'm missing something obvious, but doesn't that last paragraph lead one to believe we're about to be treated to an exploration of linkage forks? Where's the rest of the article?
When you trim the hedges the tree looks bigger
Plus, one of the main drawbacks of linkage forks is size + weight for a given amount of travel (one of the reasons they are not used in motocross). Putting a better (=bigger) damper in would increase size and weight even more.
The reviewer is pretty honest imo.
singletrackworld.com/2018/07/review-motion-ride-e18-anti-dive-linkage-fork-first-ride
They seem to be impressed with it too.
www.youtube.com/watch?v=OUsl-qb138A
What about linkage forks that don't have hairsprings, and have some short of elastomers?
It'she same reason round headlights look better than rectangular ones, and why we cringe when we see spiders and think bunnies are cute; one looks better than the other.
Plus, with all the technology put into telescoping forks, they actually work pretty good.
Another thing that keeps us from buying the linkage forks is cost. Why spend $3k, when the $1k forks work -- not just fine -- but excellently, and look better, to boot. Linkage forks are kind of like the answer to a question no one asked. That said, I think the Trust forks look solid. But yeah, the price is a little steep.
However girl number one, the pretty one, is just not interested in sex and every time she tries it's shit, but girl two shags like a porn star, is up for trying anything and gives you the best mind blowing sex you can imagine.
Which do you go for? Form or function?
Furthermore, your thought exercise is a poor analogy. In the real world, the hot girl (telescoping forks) not only meets your needs, she meets them well. In the meantime, the jury’s still out on the ugly girl (linkage forks), and the investment in her is two and a half times that of the hot girl.
Stop fooling yourself. You couldn’t convince 99.5 percent of us to put that Motion Ride contraption on our bikes. And if you’re honest with yourself, you know damn well the reason why.
Girl B is quite attractive as well. Moreso than girl A.
Girl B is telescopic forks and A is Linkage forks.
Pretty easy choice, no?
One could argue that looking good is part of the function of a product, why shouldn't all our stuff be pleasing on the eye? And if its not, then the product isn't "functioning" properly.
What I wanted to do with the thought experiment was to try and open a conversation to see if we could find the point at which function beats form: if the new fork could shave 5 seconds off a 2 minute run, would that override the "ugliness"? I guess this depends on the person; a racer would say yes for sure.
You say that the good looking option would have to not function properly to consider using the ugly option, but modern telescoping forks work just great so no need for the ugly. What if this new fork is a bit better? Not loads better, but definetly better.
The other interesting part is the idea of beauty: I remember when 29 wheels were a new thing; for me they looked just far too big and made bikes look bad, now a few years down the line, they look kinda normal and 26 looks too small! Our concept of good looking changes all the time.
I think in most cases, "good looking" is more about what we are used to seeing. How long would it take for us to become used to seeing linkage forks, to see them as normal and then "good looking"? Would it not be an error to write them off immediately cause they look bad, when in perhaps 5 years time we might think they look good?
I have no illusions about the power of beauty in our decision making process, I want all my stuff to look great (to me), but also want my bike to be the best functioning it can be, where do I draw the line?
* When the beautiful lady does not function, but the ugly one does, as I mentioned.
* When you do not have the resources/good looks to attract the nice looking lady, you have to make a trade-off for something a little more your speed. See, some of us can get the nice looking lady who's everything we're looking for. The rest of you have to settle for what you can get. At a certain point down the line, no amount of "personality" is going to make me desire an ugly fork.
* When the function is significantly -- not marginally -- better for your purposes, but the form is only marginally worse. Most dudes here would rather be with a 10 who performs like 6 than a 1 who performs like a 10. The reason? Most know they can do better. But a 7 who performs like a 10? Well, maybe we have something here. But don't be fooled -- there are dudes who will only settle for 10/10, because they have that juice. Some dudes can only have a 1/3.
1. Telescopic forks would have to not function at all. Go ahead and throw this one out.
2. They would have to have at least an inverted looks to function ratio. In other words, if telescoping forks are 10 looks and 6 or 7 function, then linkage forks would have to be 6 or 7 in looks and a 10 function. I will say, the Trust fork comes close -- I would not rule these out on looks alone. They look OK. The function is the question. From what I'm reading, they do well, but mostly you're trading one set of shortcomings for another. And they are also expensive! They would need to bring the price down -- I'm not seeing that they perform 250% better, but that is the cost.
3. They would have to be so cheap that a guy who doesn't have the resources for a 10-looking fork with a 7 function would go with a 1 look with a 6-7 function. That doesn't seem to be what's happening here -- the cost of these forks are astronomical.
I am not a product designer but I can appreciate good design (I design/build furniture.)
I tend to think that form follows function, and that form is a close second to function, but not a function itself. Great design has both. That's what makes it great. (Most times, sometimes it's simply because it broke from tradition.)
Function trumps form, IMHO, but given two products that are similar in function, I will choose the better looking product, even if it is marginally poorer function wise. Key word is marginal. I will not choose something if it under performs.
I think there are some universal truths, similar to the Golden Rule, regarding form, that we as humans are drawn to.
Sophia Loren circa. 1962 encapsulates most of them, as do certain automotive designs (E-type Jags, Datsun 240Z, Toyota 2000 GT, etc), some motorcycles and certain architecture.
Rectangular headlights rarely look good. Hard, angular shapes of the early 80's are sometimes neither functional, nor beautiful, but were introduced because they were new. I remember my mom buying expensive designer square mugs; they were impossible to clean because of the number of corners.
I don't think Pontiac Aztecs are good looking after 15 years either.
I think one can forgive certain cosmetic aberrations if a product performs exceedingly well, but there will always be the lingering taste of ugliness that hangs over a product.
In this case, the function of these forks isn't that much better than telescopic forks, they don't look as good, and the price is more.
I appreciate that part of this is because SO much money has been put into refining telescopic forks.
I actually don't think the Trust fork is bad looking at all.
Really looking forward to hearing the review on this one.
Instead of FOX and RockBox developing new air-spring units, two super small brands developed air-springs for fork and shock that outperform those of big manufacturers. If bike geometry isnt changing constantly, telefork damper requirements would settle down. And it's the damper that makes the biggest difference (if we ignore wrong air-spring curve, ireperable bushings play, ...).
And what will be there to develop? New insane axle nonstandard or re-introduce 20x110mm dimensions? Will they add another pair of bushings? They dont even develope fork crown-and-steerer monobody unit out of carbon or 3D printed steel.
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IMO, the ONLY advantage of telescopic fork is that it is the most optimal solution to a given problem. And as we know, the most optimal is the most svcker because it cannot do everything to its best.
.
Like your insight and potential for linkage systems for clever rate curves is great but most mortals will never notice.
IMO best advantage of tele is price+performance (+simplicity).
(and I need to ask ... does sucker = compromise?)
At Structure we'll never argue that bikes with telescoping forks can't be great. Our argument is that linkage system offer advantages that are too great to ignore. A two-minute ride is all it takes to notice a big difference. Check us out at structure.bike and get on a demo this summer if we get out your way.