First Ride: Tantrum Cycles Missing Link Suspension
The Tantrum Outburst is a 125mm-travel 29er with modern geometry designed to showcase Missing Link suspension.
Brian Berthold may not be on your short list of mountain biking's most notable inventors, but perhaps he should be. Berthold carved out a reputation as a capable suspension designer and crew chief in both off-road and Indy car racing. Then, mountain bikes caught his attention, and after a stint as a downhill racer, he started tinkering with suspension and brakes. Berthold founded Therapy Components, where he developed and marketed a beautifully made, inverted dual-crown downhill fork, followed by an aftermarket floating disc brake kit that was designed to eliminate unwanted brake inputs from the sometimes scary rear-suspension kinematics of the time. Fast forward about ten years, and Berthold again blipped the mountain bike radar when he invented a variable-rate/variable-travel rear suspension linkage debuted by Kona as the "Magic Link."
Brian Berthold poses with his Tantrum Outburst on Rocky Peak.
Kona Magic Link
The Magic Link was Berthold's first breakthrough invention in the cycling world. Using a simple linkage, Berthold created a rear suspension that, when pedaled, reduced the suspension travel to 100 millimeters and increased the spring rate - and would seamlessly switch to a softly-sprung, 150-millimeter-travel suspension the moment the wheel contacted a bump.
Berthold attached the forward swingarm pivot to a short lever below the vertically-mounted shock. Chain tension swung the lever forward, reducing the shock leverage rate and wheel travel, while bump forces pulled the swingarm rearward, which reversed the position of the link, increasing the leverage rate and lengthening the suspension travel. Berthold used a small spring to hold the linkage in the short-travel pedaling mode and to control the action of the transfer between long and short travel modes.
Berthold's Magic Link was a simple, mechanical method to address the need for a firm-pedaling, long-travel rear suspension, but it did not catch on. Kona's rough execution of the concept was partly at fault, but Magic Link was ahead of its time - all-mountain and enduro bikes were still over the horizon, and the novel-looking Magic Link was neither well understood, nor well received by the press at the time.
The Magic Link was Berthold's first breakthrough invention in the cycling world. Using a simple linkage, Berthold created a rear suspension that, when pedaled, reduced the suspension travel to 100 millimeters and increased the spring rate - and would seamlessly switch to a softly-sprung, 150-millimeter-travel suspension the moment the wheel contacted a bump.
Berthold attached the forward swingarm pivot to a short lever below the vertically-mounted shock. Chain tension swung the lever forward, reducing the shock leverage rate and wheel travel, while bump forces pulled the swingarm rearward, which reversed the position of the link, increasing the leverage rate and lengthening the suspension travel. Berthold used a small spring to hold the linkage in the short-travel pedaling mode and to control the action of the transfer between long and short travel modes.
Berthold's Magic Link was a simple, mechanical method to address the need for a firm-pedaling, long-travel rear suspension, but it did not catch on. Kona's rough execution of the concept was partly at fault, but Magic Link was ahead of its time - all-mountain and enduro bikes were still over the horizon, and the novel-looking Magic Link was neither well understood, nor well received by the press at the time.
Kona's Abra Cadabra was the last of its Magic Link models. Chain tension and bump forces from the swingarm toggle the lever below the shock - forward to reduce and stiffen, and rearwards to lengthen and soften the suspension's travel. The tiny air spring connected to the lever adjusts the sensitivity of the Magic Link as it switches between modes.
Berthold's Missing Link
Undaunted, Berthold maintained that the ultimate long-travel trailbike suspension should pedal perfectly, provide traction on uneven surfaces, and absorb bumps - all without employing electronics, remote levers, or compromised damping effects. He further simplified the basic elements of the Magic Link, eliminating its spring-loaded control mechanism, and ended up with an elegant solution that employs two naturally opposing forces on the swingarm to either activate, or to completely lock out the shock. He dubbed it the "Missing Link," applied for a patent, and began to search for a bike brand in need of new suspension technology.
At full extension (illustrated here), the two links that drive the shock are aligned vertically. They essentially become a fixed column that mechanically locks the suspension. Until the rear wheel contacts a bump and levers the two links out of position, the Tantrum is truly a hardtail. With rider aboard, however, the shock sags into its travel like any other suspension. While riding, the Missing Link only locks out in response to chain tension generated when pedaling.
When Berthold paired up with Kona, long-travel trail bikes were not the rage, so the Magic Link was a hard sell. Later, after he developed the Missing Link, enduro was raging and the average trail bike was pushing 150 millimeters of wheel travel. It was a perfect storm, and Berthold assumed that his simple mechanical solution to the genre's "perfect pedal/perfect suspension" conundrum would be snatched up by a number of forward thinking brands - but he found no takers.
"Each time I showed the Missing Link, the response was the same," said Berthold: "It works great, but bikes are pretty darn good right now and we don't want to allocate the time and expense to develop a new suspension." Berthold threw up his arms. "So, this is it? Bikes can't get any better, so we all should just stop trying to improve them? That's weak!"
The swingarm attaches to the Tatrum's Missing Link. The swingarm only moves a few millimeters fore and aft to activate the link.
Conventional seatstay pivots and a bolt-on dropout/caliper mount assembly that future-proofs the frame against new hub or axle standards.
Tantrum Cycles
Berthold then took a more direct route to bring his Missing Link suspension to the marketplace. He put on his Mechanical Engineering hat, switched on Solidworks, and designed two welded-aluminum trail bikes: The Meltdown - a 162-millimeter-travel all-mountain/enduro bike based upon 27.5-inch wheels, and the Outburst - a more trail-oriented 125-millimeter-travel 29er. Using his own money and contacts he had previously worked with in Taiwan, Berthold founded Tantrum Cycles, which will be selling direct to customers as soon as July.
I rode the Meltdown - a 160-millimeter chassis with 27.5-inch wheels, and geometry that fits squarely within current all-mountain/enduro trends.
 | So, this is it? Bikes can't get any better, so we all should just stop trying to improve them? That's weak! |
The idea is to sell some Missing Link bikes, get his new suspension system under some riders, solicit some good press and hopefully, make a little money in the process. Berthold says that Tantrum initially will only sell frames, which makes sense, considering the massive investment required to produce complete bikes. If all went well, Missing Link could gather enough momentum to nail down a licensing agreement from a reputable brand.
First Ride on the Missing Link
When the first production frames arrived, Berthold gathered up enough components to assemble a Meltdown and an Outburst, flew to California, and invited me out for an opportunity to ride the bikes. I chose a zone north of Los Angeles that would exaggerate the strengths or weaknesses of a good cross-country bike as well as a pedigree enduro machine. Lots of rocks and dust, technical ups and downs, extended climbs, and speeds that varied from suffering upwards at a walking pace to mach chicken descents.
I rode the Meltdown, partially because, with a bit more than 160 millimeters of suspension travel and 27.5-inch wheels, it was more representative of the present market, but mostly because I was curious to see if a trail bike with that much squish could actually sprint and climb like a hardtail. Heard those words before?
First Ride on the Missing Link
When the first production frames arrived, Berthold gathered up enough components to assemble a Meltdown and an Outburst, flew to California, and invited me out for an opportunity to ride the bikes. I chose a zone north of Los Angeles that would exaggerate the strengths or weaknesses of a good cross-country bike as well as a pedigree enduro machine. Lots of rocks and dust, technical ups and downs, extended climbs, and speeds that varied from suffering upwards at a walking pace to mach chicken descents.
I rode the Meltdown, partially because, with a bit more than 160 millimeters of suspension travel and 27.5-inch wheels, it was more representative of the present market, but mostly because I was curious to see if a trail bike with that much squish could actually sprint and climb like a hardtail. Heard those words before?
Setup: Brian suggested that I set the suspension without factoring in pedaling firmness. That may seem like stating the obvious, but it reminded me that most of us fudge our spring and damping settings a little to ensure that the bike will pedal well enough in the open settings to cover the many moments when we can't reach the lever on the shock. I chose somewhere between 25 and 30-percent sag for the shock and 20-percent for the fork, and I adjusted the rebound a little fast in anticipation of the quick, chunky descents ahead. Both bikes were outfitted with X-Fusion forks and shocks, which tend to deliver a firm ride in any setting, so I didn't know what to expect when we rolled up to the trailhead.
Climbing and pedaling: Turns out that the Meltdown actually did feel like it had a rigid rear end under power. Beyond the fork compressing, there is no suspension penalty for jumping out of the saddle and pounding on the pedals with abandon, and seated pedaling feels equally efficient. Sweet, but after being briefed on the Missing Link, I expected that. What I didn't expect, was how seamless the suspension kicked in when I was fighting my way up the trail's technical rock problems. I was sure that the linkage would feel notchy as it unhinged back and forth from completely rigid, to a decidedly plush 160-millimeter rear suspension. Berthold explains that the scissor-action of the two links initially creates a falling leverage rate, which maintains some pedaling support as the suspension transfers from rigid to plush mode.
Descending: Both bump forces and rear braking uncouple the Missing Link, so the Tantrum's rear suspension is never locked on the downs. In fact, the suspension sags farther into its stroke at speed, which lowers the bike's ride-height slightly, slackens the head angle and adds a measure of stability. Whether the Missing Link returns to full rigid when pedaling out of corners is not apparent, because the chassis feels consistent. Theoretically, the rear end must rise slightly under power because the shock is pushed towards full extension, and I could feel that happen while I was climbing, but I did not sense that occurring at any point while I was descending.
Observations: I noticed that the fork was overdriving the rear suspension while I was at speed and working the bike hard over the zone's chunky sandstone. Much of that could be attributed to the X-Fusion fork, which performed poorly over sharp-edged impacts. The harsh feeling fork probably exaggerated the tendency of the rear suspension to settle into its stroke, so potential customers should choose a fork that is suppler in the pointy bits.
First Impressions:
| Brian Berthold's Missing Link delivers the goods - direct drive pedaling with supple suspension action - and it does so without electronics, remote levers or voodoo shock damping. Compared to the current crop of carbon superbikes, the Tantrum Meltdown looks rough around the edges, but it performs well on the downs - essential for any 160-millimeter trail bike - and its pedaling action is better than all of them. Bold statement? I've ridden many trail bikes that were supposed to, '...pedal like a cross-country bike and descend like a DH bike.' (I've written that phrase more times than I should have) Only two have actually performed that ballet: the Meltdown with its Missing Link, and a Kona Process outfitted with Fox's prototype Live Valve electronic suspension. Neither are perfect, but both set the bar well above today's crowded pack of carbon uberbikes. Send the Meltdown to finishing school, add a better component selection and a more sophisticated fork and shock, and I think it has the potential to take on the big guys. Brian Berthold's Missing Link is proof that there actually is significant room for improvement among the present crop of all-mountain trail bikes. Cheers to thinking outside the box. - RC |
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I just put a 150 mm fork on the 29er. Fun. Even more fun with the 165 mm 27.5 rear end on it.
We might squeeze a little more out of the 29er rear end, but not for 2017.
I do like the idea of 165mm 27.5 rear and 29 front, sounds like a lot of fun
Sizing is in fluz. S, M, L will be Short, Med and Long. I'm going to stretch the reach as much as I can between sizes, while keeping relatively short ST. The new L is 460 mm reach
The 29/27.5 combo has the big wheel rollover in front, where you need it. It also has the long travel bump gobble in the rear, because sometimes, you just have to hit stuff with the rear. The smaller rear wheel also makes the handling a bit quicker, more fun, but the bike is more stable due to the travel.
Tantrum only as four followers, me being the forth. www.pinkbike.com/u/tantrumcycles Let's see what this guys bright future has in store! Cheers to Brian for not sticking with the status quo!
Complete weight as tested 29 pounds with pedals. The frame with no shock is 3232 gms, about 7 lb, 2 oz.
I'm not saying they can't be moved, but that's for future development. I had run thru hundreds (if not thousands) of iterations of moving points by the mm, to get all the right reactions in the right directions. i do know this, in the current configuration, if you move things by much ( a couple mm), things get wonky in a hurry. That's one reason that I'm so amused by those making definitive statements of poorly scaled photos.
This is my 4th iteration in metal, making fine tuning changes along the way. It's pretty dialed, performance wise and will go into production this way. One advantage of this layout (as opposed to the horizontal shock) is a lower CG. All the sus parts are LOW.
The CS, wrestled with that forever. I used the straight LS CS on the g2 Magic Link bikes, but, I don't like the asymmetric look (or potential feel when landing from a jump) and it makes the CS bridge a mess and takes away some stiffness due to that.
As for the SS, the frame is a M/S, so on the new Med, they'll be more in line and on the large, they, be a bit under the TT. So, it's hard to make that line up with all frame sizes.
Thanks for the comments, I'm sure in the future I'll discover plenty of new possibilities. Not done yet.
After reading this article, I actually laid out a version of your rear with more horizontal shock and SS placement and mocked it up in the shop using MDF. The system functioned (as well as could be expected in MDF), but I'm sure axle path, shock tune, orientation, and length can quickly become issues (wonky, like you said). Very intriguing. Are you still interested in licensing the rear or co-developing the design further? (We're doing virtually everything in carbon)
Regardless, I wish you all the best growing your brand. I have some idea of the challenges you've overcome to get this far, and I hope I get to ride a Tantrum in the near future.
Cheers,
Lon
You never know, though...
Hint: 27.5" carbon enduro, 150+mm travel, 344mm BB, 65° HTA, and a 1200mm whelbase in a size L that still has reasonable reach numbers. Eagle X01 and Super Deluxe RC3 trunnion in a bike built in the Canadian Rockies to take on all comers in enduro racing. That's all I can reveal for now... ;-)
www.kickstarter.com/projects/812273700/tantrum-cycles-the-missing-link-in-full-suspension
Really great response so far. Still have frame/shock starting at $1400 and completes starting at $2600. Special kickstarter deals
Did PB just try and set up up with that poll earlier?
Or companies can sign up for a free account, answer the polls and then receive said data, instantly, for free.
Not sure if there is a flaw in your argument there somewhere?
............ill let myself out ;-)
As RC mentioned, the ride had it all (including me pushing a LOT). But it was a great acid test of EVERYTHING. Some components faring better than others. As belabored, the fork was a little overmatched. As was pointed out, this was more of an entry level fork that was graciously loaned to me (thanks Joel ), so that I had something to attach the front wheel to (thanks Len). I explained to RC that the build of the bikes was indeed a mix of components that we were testing for possible inclusion into a lower and/or higher priced spec. All of the components were pretty much competitive market products worthy of consideration.
I wasn't that concerned with how much the overall component mix affected the perception of the bike, as my engineer brain said that everyone would just focus on the suspension. I think, for the most part I was right, with the glaring exception of no dropper post!!! and graphics. and fork. and the aluminum frame. Thankfully, RC was graceful in his criticism, realizing my lack of presentation skills. When we offer build kits, they will be dialed.
Graphics. For the first time in my life, I hired a high zoot, well regarded artistic graphics team. Except for the head tube badge, for which I blame myself. I told the graphics team it was a show bike, make it stand out. It sure worked. In reality, it is not mass production friendly and will be simplified. I have 2 versions being worked on by new people. Who knows? See at Euro/Interbike. The HT badge stays.
I'll try to answer some of the more pertinent questions in the thread, but it's long, so feel free to ask.
b
It looks like you have done something really interesting here and could be a big hit with certain riders.
One thing I would say is that the geometry is outdated and I think if you are going to sell a decent number of bikes, they need to have longer reach and TT measurements.
If you tweaked this and a few other bits (as mentioned the graphics) and make the link more aesthetically pleasing I think you will be on to a winner.
As it stands a 20" ST with a reach of 440mm is just too outdated for most people to jump on board. I am 6'3 and ride a 19" bike with a 485mm reach.
Ok my bike is at the extreme end of the spectrum, but something in between the two would stand a better chance of selling more bikes.
I think it would be a shame to have such an well though out and innovative bike, being held back by such conservative geometry numbers.
A far as an early production/test mule goes, I don't think you have to put any effort into getting us engineers and engineering types to look into the merits of the design, and details of the bike. That's in the bag.
I think investing in a bling heavy (at least where it is visible) T&E / technology demonstration bike would be worth it, especially in occasions like this. The frame-only market is dominated by internet and bike shop denizens who are meticulous about sourcing high end stuff, and being reliant on what parts you can borrow means something as simple add having the RL2 damper in that fork colors even a highly favorable review of the complete bike.
It actually means a lot to see how unconcerned you personally are with decking out a press bike with expensive parts to make the point about missing link being an excellent platform, unfortunately I'm in the minority regarding that outlook.
TL;DR: I think a press bike with bare aluminum and understated anodized finish to look like a test mule, but spending money on a Fox 36, high end dropper, and XT drive train would be a very worthwhile investment.
So in my "tester mind", I always have to separate the effects and try not to let one components ruin the evaluation of another. I do realize the folly of this in terms of the market place, and certainly in the case of the fork, it is obviously going to affect the action of the rear. But I do want to be able to sell a more affordable build kit, so I need to be aware of all of the options.
So, I really didn't look at this as a "press bike". And we're not selling complete bikes, or even build kits yet. Bad timing for this test to have that fork? Yes. Dumb move in retrospect.
But I'm happy that RC is also a tester and can separate that (to a degree) when evaluating the suspension.
We'll have the chance to test the complete bike this fall, all blinged out.
I also appreciate your desire to offer more affordable build kits, or builds as unlike most (it appears) on here I have a very limited budget to spend on my biking passion.
i'm lukewarm on the exisitng graphics, which I outsourced (except the HT badge). Got now guys working on new graphics. Who knows? But the HT badge stays.
I do want people to be able to afford the bikes. If I can offer good value at the weight of a carbon bike at a lower price.........
That sounds in the right ball park for modern geometry
If I was in the market for a 20" frame, I wouldn't go for anything less than 460 reach and maybe a tad more.
Most people will be happy to go a bit shorter on the stem than 50mm, but the amount of people who will ride longer than 50mm is becoming smaller and smaller.
This article is worth a read if you haven't seen it: www.mbr.co.uk/news/size-matters-why-were-all-riding-bikes-that-are-too-small-321374
While I think Chris Porter is pretty extreme and I don't agree with everything he says, some of what he talks about makes sense. A lot of companies are moving towards longer reach figures and within reason, makes for a better handling bike.
For each ST angle/TT length, there can be only 1 possible reach. But for any given reach number, there are an infinite number of ST angle/TT lengths that can achieve that.
I do agree with one important point CP made. Why only 10-20 mm difference between frame sizes? We are trying to fit riders with maybe a 10" range in height with a range of maybe 3 or 4 inches in reach.
Toward that end, I am pushing 30 mm reach different between my S, M and L, 400, 430, 460. Is it enough? Is it enough for 6'4" rider? I don't know, but I will say, that with my slacker ST angle, the effective TT length will be longer than for a similar reach measurement.
Yes I think that is the one thing I think most people agree on. Reach numbers have been too conservative for a lot of bikes and companies are starting to wise up and make longer numbers between sizes.
I think you could bump it up by +5/10mm which would one; give taller riders 6'3+ a chance of fitting on a L without a long stem (lots of people won't run a stem longer than 60mm on a trail bike now), but also give those in between sizes, the chance to run a shorter stem if need be (35/40mm)
I have an inside leg measurement of 35" and can easily ride a 19" frame with a 150mm dropper.
Having slightly smaller ST numbers would again give a bit more versatility between sizes due to difference in leg lengths and that most people run a dropper these days.
@spectacularspectacles Aesthetics are very important, but so is creativity and uniqueness. I would suggest that the look of their bike is establishing a solid brand identity. I must admit that yes, SCs bikes do look great but there are also plenty of bikes that look as good with much more character. I value character above all - in fact the most badass bike I think i've ever seen is Cam Cole's Ellsworth from a few years back, it just screamed fast and brutal.
If I had to guess, that's more of a "We are making a lot of money off of what we're doing right now and we're too greedy to change anything cause we like making money."
HOWEVER, this design will not succeed, simply because the same can be achieved with electronics. And we all know that if something can be done with electronic, it eventually will be. Because in the end electronics are cheaper to produce, you can put a lot of gadget-like features AND electronics fail faster, so you earn more money on service.
However, I will continue to believe there will be a market for a non-electronic based solution. True, someday, there will be a bike with electronic front and rear sus, shifting, dropper, braking, maybe even drivetrain!!!!. But, I would like to market and sell a mechanical device that does it more simply, for less money.
I think there are people with me on that
Actually, the anti-squat wasn't my point. I only wanted to say that this design isn't really magical and it's close (or not very far) to existing designs, because it has a fixed axle path (or other parameters that go with it, like IC potition curve, or whatever you need for your analysis) and a fixed leverage curve, so it works like any other bike. only the compromises are differents. There is no magic in bike kinematic, as soon as you have the leverage and the axle path, you can forget all you know about the pivots locations, the shape of the links, or whatever, and write the matrix describing the reaction of the chassis to every force you need (in 2D analysis without thinking about the flex)(matrix will also show where goes the energies). The matrix of this bike will have the same size as the matrix of every bike that has one shock (bikes that have one degree of freedom when shock is removed).
And, when you have this matrix, you can try to obtain a close or similar matrix with a more conventional design, the bikes with close matrix will have as close riding characteristics.
And "anti squat" here will have the same effects as every bike with one shock in the rear suspension, but as "anti squat" is, in my opinion, non-relevant in bike analysis, you actyally can't say anything about it.
@tantrumcycles
no, your design actually does thing the same ways, only the compromises you used are different. I read the beggining of your debate with "Vrock", in the link here in the comments and saw your videos. and I can say that your bike may work as you say, but not for the reasons you mentionned. You can argue that the anti squat doesn't represent many things, but you can't say the same logic don't apply to your design, as the physic won't change.
Like, if I apply classic rules. "if the chain tension lift the bike, there is loads of kickback". So does your design have loads of kickback? Yes, It has. Just see the video you posted when you actuate your suspension without the shock: you see the front pedal lifting under suspension action. And when you push on the pedal the suspension lift (or doesn't fall). Like it would be with high "anti squat", "chain growth" or "IC heigh" values, the same rules with any other bike with a similar matrix applies.
I digress and I don't think I'm saying everything I want so I will stop here.
I think Your design may have potential, it surely works well in the "more travel that works like less" category, and many buyers will be happy. But please stop hurting physic.
If that is true, I am the single, luckiest person on the planet.I have manged to design a complicated mechanical device that does exactly as I predicted, for all the wrong reasons. It might not quite be the apple falling on Newton's head, but I'll take it.
If you apply the classic rules of anti-squat, you are correct, if there is enough chain tension to lift the bike, there is loads (technical term) of kickback. Does mine have some? Like every non-concentric pivot bike, yes it does. Like probably every full suspension bike you've ever ridden. How much is too much? When you feel it, when it hampers your cadence. In this case, it does not. Certainly not where any tester has noticed, even when specifically asked to look for it. Just for fun, take your shock off and compress the suspension and watch the pedal feedback.
So, maybe I'm not doing it with excess AS. Maybe the force inputs from the Missing Link ARE responsible, and do not require excess chain growth to accomplish. Maybe that's why I can do the things I claim.
Physics are our friends, It is fun to hurt them back, when given the chance, since they've caused me enough pain over the years. But while we're on the subject, throw down a few free body diagrams for a real idea. Physics 101. Don't they teach that anymore?
I don't know if you didn't explain what you actually did, if I don't understood correctly (I don't speak english really well), or if you're lucky, but what you said in your videos and wrote to several people can't explain why your bike work.
I won't say there is too much kickback, as it would require a full analysis of the dynamic of the bike, and results will vary for each crank arm/shock/ chainring size... I was just giving an exemple of your bike acting like any other out there, compromises are the same. And no, not every bike has kickback. some exemples of bikes that doesn't have kickback: a single pivot bike with the pivot lower than the chainline, URTs, idler pulley bike with the pivot or IC lower than the chainline...
Force input from the missing ling have obviously an effect on the suspension, but so have the force imput from the seatstays, and same with all the parts. Thats why I mentionned axle path, IC curves, and other things, they summarize all the effects so you don't need to know what happens in each part anymore (to study the 2D suspension, you'll need that everywhere else)
Actually your missing link does give the axle path a great rearward motion, that axle path gives chain growth, kickback, anti squat, pedal bob (but upside down, as you lift the bike), and many other things. If you didn't take into account the other parts, you are actually lucky because at the beginning of the travel it has a preponderant role in the axle path.
I won't draw a free body diagram (I just learnt the english term so thank you), as I already know what I will learn: quite nothing. but put some parameters on them, "solve" the equations that link these parameters, and you can sart to fill the matrix of the bike, that will show you everything at every moment of the suspension action.
It needs better graphics and RS or Fox suspension with fast black/Kashima and a dropper post if it is going to sell, though. The graphics do not compliment the aesthetics of the frame.....it really clashes and with the price of bikes...you're damn right looks are important. We have to ride these things for 5-10 years before we pawn enough heirlooms to buy another one.
This is set up for an ugly-duckling story. Make it happen!
You think the fox dropper needs to be Kashima coated? Of course not, but if you're willing to spend a little bit extra, you get the bling.
Works in every industry, and it IS a deal breaker whether the smart consumer thinks so or not. Solid product that looks good....I'd rather have that then a solid product that looks "cheap"
I personally have no issue with Manitou or Xfusion or BOS. But stack anyone of them against a factory fox to the masses, and they will buy the fox.
Also, buying the cheaper option with the intent to upgrade is more expensive. You've bought a oem product (fork for $500 built into bike price) that you can't sell with a gauruntee or warranty so you sell it for less than its oem price especially if it's used ($350), then you pay the oem price for an upgrade vs it's oem price ($900 vs $700). So instead of spending $700 for the upgraded fork you originally wanted, your spending $1050 for the upgrade. On the flipside, you can make money if you're super smart and your buyer is super retarded.
IF you can afford what you want in a package....consider the savings.
BTW purchasing power goes a long way in savings which is why Jensen and CR can offer such huge savings.
In a head to head. All things being equal, the better looking product will be preferred.
I really hate to be the one serving the coolaid but imagine how fast true beginners could progress if there was a +size in this for Ones who really need the characteristics this offers.
Nice wife who doesn't ride would really enjoy the benefits of this on the off occasion she tries to ride
AND I do like the idea that this might help keep electronics where it belongs- in the office rather than on my bike.
After I get another fork for this other frame(Hornet), I'll be looking at Gravity Dropper. Though, for the sake of being a 40 year old MTB'er I'm patiently waiting for the release of the Orbea Digit Dropper just to check it out.
Digit Dropper would be the one extra part I'd like in my truck just in case my primary dropper goes south. Though, I don't expect maintenance issues with the Gravity Dropper.
Okay, sorry for going off topic. Keep on throwing down the awesome articles, and keep shredding!
Get real bud.
You must live where it's flat. Or have no clue what's going on out there.
The rearward force to activate the scissor action is only necessary when climbing or pedaling hard. Because that is when the "stiffening" effect is in action. If you are coasting, you will get an extra degree of compliance from this action, but the shock would never be at full extension with the pedaling biasing force.
Does that make sense?
Yo Brian. Yeah, sorry for the poor literacy. Don't know how I confused Richard. Good chatting at the otter. Best of luck and really nice looking bike! Hope I get to try one someday.
I suspect the Missing link patent is an invention that will become an milestone in bike suspension history. But since so many seems to be more concerned about how bikes looks then how they ride, I guess it might take som time.
Keep up the good work Brian! It world be so cool if Tantrum could grow to become a reputable brand by its own, and let the sceptics keep on tinkering with there platforms, switches and compromising sag-settings..
Imoh a good read even for the less open-minded, sceptics and haters around ;-)
I'm proud to have sign up for production frame NR:1 !!! :-)
As for clit play... you heard me lol
"'...pedal like a cross-country bike and descend like a DH bike.' (I’ve written that phrase more times than I should have)”
I know a guy that refuses to read MBA and other bike reviews because he swears they’re all puff pieces for bike companies. I’ve always presumed that you’re giving us the 100% low-down on a bike. Did that sentence mean that you’ve written that about bikes that didn’t really climb/descend as stated?
Is it necessary? I mean, the climbing and decent performances of this cinematic sound otherworldly, but nothing is perfect and with shit-loads of links and an odd attach point for the shock come maintenance and weight ( mtbers are weight weenies at heart),and maybe others. My point is, today we have voodoo technology in shocks that allow us to radically transform how a bike climbs. Is it more clever to have a simpler design( vpp, 4bar...) and a lockout/climb-mode or a magic link? I can't help but smile when I read "Omg, that's uber-cool, I don't need to switch to climb mode to go up.", well, my 2009 remedy isn't that much of a climber at heart, but turning a flick makes it very easy to ride it uphill... while having 35+%sag for the downhill.
I don't want to sound negative, I am just rightfully wondering. And props to Brian for achieving this, an evolution is always welcome and doing it all by himself is impressive at least!
The real bullshit is when Berthold demonstrates the function in his videos with the shock unattached, which allows the two shock-driving link to rotate more than they would otherwise. Then, it's noted that when the shock is attached the links don't actually hit the seattube.
The actual degree of rotation of the links in the video is not really relevant to what I was trying to show. Obviously, neither was the contact from having the link over-rotate. the demonstration was merely to show the direction of the horizontal forces as they are fed into the linkage. Those forces are real, as demonstrated and they affect the linkage as I am showing in the video. Once the linkage is re-assembled, the forces still act the same and affect the linkage as a whole.
My point is that in his marketing material, Berthold suggests that once in it's "locked out" position, the linkage will stay that way until acted on by bump forces (he specifically attempts to illustrate this in the video with the shock unattached), but I disagree. If there was some mechanical way for the linkage to go past top out so that it was actually pulling on the shock and stuck either against the seattube or stuck by trying to pull the shock past top-out until a bump force shifts the lower link (as he specifically demonstrates with shock unattached), i could imagine the possibility of what he is suggesting, but because of the clearly shown alignment (with the shock atttached) of the shock-driving links ensuroing that vertical wheel travel always moves the shock mount forward, and the fact that the bike always sags into travel without chain tension, it's obvious that any "lock-out" effect is momentary, very dynamic, and driven by high AS, and as pointed out by Vrock, aided by the falling rate LR. We are in total agreement, i was just using a more visual way to look at it.
"If you pedaling effort is reduced the sag will gradually and proportionally increase. As you reach the top of the climb, the sag will return to static level even as you keep pedaling to finish the climb." (as you do below in this discussion)
and then disagree when I say this:
"Berthold suggests that once in it's "locked out" position, the linkage will stay that way until acted on by bump forces (he specifically attempts to illustrate this in the video with the shock unattached), but I disagree...the fact that the bike always sags into travel without chain tension, it's obvious that any "lock-out" effect is momentary, very dynamic, and driven by high AS"
Whether it's right or wrong, you have to pick one of them to argue.
So, while you say the "lockout effect" is momentary (as, indeed, it would very much be if only the product of AS), it is in fact, very consistent throuought a climb, as my videos clearly show. A high AS suspension cannot demonstrate this behaviour. It will relax into the travel at the dead spot in the crank stroke and inchworm its way up the climb. If you've ever ridden a C'dale super v, super 8, bullit or the like, you will know exactly what mean. Along with the real definition of pedal kickback. Those are all very high AS bikes. Bad. Gone. Good.
Again, the lockout only occurs at high pedaling effort due to climbing. It will stay that way until you hit a bump or cease climbing.
The suspension behaviours that we are discussing are sufficiently interesting and important that they rightly command our attention despite the lack of agreement over how the effects are produced.
Hey, my first one was, gasp, 26" wheels and 135 mm rear end. What was I thinking?? Fun bike, though.
The website, etc, will all be updated soon. With production graphics, don't even ask, I haven't seen any concepts, yet.
I have zero understanding of suspension design, but that sounds odd. Yeti recently spent time and $$ on two unique suspension designs. Specialized and Santa Cruz built premium brands around patented suspensions; patents that just expired. Now competitors are selling those same suspensions for less. I imagine Specialized and SC are desperate to find a new market differentiator and would love to license a superior new suspension. They must have a reason for passing on Berthold's design.
Add on the costs for molds, development time and costs (why Specialized and Santa Cruz still have an edge working with Horst/VPP designs), and the fact that certain markets have hour early saturation points (primarily because most every bike rolling onto an LBS doesn't suck our break prematurely) and it's hard to make a risk justification to invest huge money into something new and different if status quo is still profitable.
Cannondale are mostly closing of the Dyad pull shock add a technological oxbow, and moving back to conventional suspension and linkage driven single pivots. Yeti figured out how to make a translating pivot not work poorly, though in my experience it's very much a dual-link type experience with really high anti-squat that blows off into mid travel and feels critical regarding chain tension and LSC tune.
To answer your question, the only one of those trying something unproven already had switch infinity prototypes, and it's easy to recoup R&D costs when selling $3400 frames promoted by a top notch EWS effort.
The bikes are med/small and there are limited spots, so let me know if you're interested. We'll have the 160 x 27.5 Meltdown and the 125 x 29er Outburst.
As this linkage is made to work as intended without complicated and expensive propedal and I would guess a advanced piggyback shock might be overkill for me q since I also have 25% to face and also intend to cash out for 1x12 drivetrain, good brakes and decent wheels.
www.tantrumcycles.com/meltdown.html
Looks good to me
Kudos for pushing the envelope though.
To me, the mid travel 29er is attractive, since getting a bit more pedaling efficiency is always nice on a bike that can keep it so well, with more capability in the bank for rugged all mountain use.
1st place
sea otter 2018 mens cat 2 downhill 25-29
Karl Lange
riding a 2017 Tantrum demo (DVO front and back)
[from the 1st Kickstarter batch]
In the video, when the pedal load locks out the suspension, the "missing link" appears to lock itself out by resting itself "enthusiastically" against the seat tube with a metallic "clunk" that would become worrying after 20,000 cycles...?
Did you notice this happening out in the field as the shock fully extends, or does the shock limit the movement of the linkage to stop it hitting the seat tube?
I looked at the video explaining this linkage - see
www.youtube.com/watch?v=uh44UMTOmB0&feature=youtu.be
That is a weird experience. Brian, the guy doing the talking, disconnects linkage pivots in order to explain how the linkage works. But, that is an entirely invalid move, because the linkage can only work at all as a connected whole, that moves as one system, not as a series of free parts.
Also, a claim is made that chain tension from pedalling can hold the linkage in a position that keeps the rear suspension in a fully extended state. First, that claim doesn't amount to much because for a bike with a properly adjusted SAG, there is no amount of chain tension (that can be generated by a rider) that can somehow lift the bike up and hold it there when its natural tendency on the contrary will be to return to SAG. Second, in the only imaginable circumstance where chain tension might produce the said effect - after the suspension fully extends due to a dip or leaving the ground - if chain tension holds the linkage and suspension in a fully extended state, that would be a very bad thing. Chain tension would be overriding the normal and correct behaviour of the suspension to return to SAG according to its natural and correct function with a ill considered operational scenario of holding the bike in an extended state for no reason. As the claim is very probably untrue, in any case, perhaps, there is little reason to worry about this. Finally, not just the claim about the effects of chain tension but everything that Brian says is dubious. He talks about a lot of forces that don't exist and fails to talk about the one that does - anti-squat. A normal analysis of this linkage and bike provided by the Linkage program or something similar will give the true picture of how this bike acts when pedalled.
He says,
"At the end of the day this bike follows the sames principles as any other bike. It's a Virtual Pivot with a "Spike" of Anti-squat at the beginning of the travel 180% at 0% and 120% around 25%. The Leverage Ratio has another "Spike" at the beginning of the travel where it goes really low (1.6), but around 25% it's quite normal (2.7)."
"If you are pedalling slowly, the bike it's going to stay around sag like any other bike and work the same as any other bike with 120% of Anti-squat. If you start pedalling really hard it's going to extend, top out, and stay there for a while, because that LR (combined with that AS Curve) works "as a trap" for the rear wheel. If you hit something and you keep going the bike it's not going to absorb the bump, but I think that there is an instinct to relax a bit when you hit something really big, if that happens the suspension can react to the bump."
So, interestingly i) there is an extensive effect from pedalling (which I didn't expect) but ii) it is largely due to acceleration and an aggressive anti-squat curve and not at all due to the effects of chain tension, except insofar as the latter causes the rear wheel to turn and the rate at which it turns as well as an aggressive LR curve that complements the aggressive anti-squat curve with a very stiff pre-SAG LR spike stiffening the ride even more and finally, as I already suggested iii) the extensive effect seems to serve a purpose that is probably ill considered.
That all this can appear to be the effect of chain tension arises from the fact that the anti-squat kicks in when a rider really get on the pedals at or around SAG.
It a couple of extra bearings and some links instead of a mini shock to control it is the basic gist of it and that sounds good and reliable to me
I have not said at any stage that a rather unique management of forces couldn't have been achieved by the Missing Link. What I said was the linkage can and should be analysed in conventional terms because it is a 6 bar linkage. You are now publicly stating it is a 5 bar linkage but anyone can count them and after counting them will conclude otherwise. Regarding the conventional analysis of the linkage, I have already deferred to Vrocks analysis (I provided the link) and acknowledged that it is possible for a suspension "to go to full extension purely from chain tension induced anti-squat." And, indeed that is what is happening here. Chain tension induced anti-squat lies at the heart of the way this linkage works and a very low pre-SAG leverage ratio also features and firms up the ride in the way you have claimed. Still, it would be a fantasy to claim that chain tension on the Tantrum bike works like it did on the Magic Link bikes. On those bikes you could actually effect a small change in the dynamic geometry and wheelpath of the rear suspension. Nothing like that is possible with the Missing Link. That you are employing anti-squat to achieve certain functional characteristics of the suspension and (with the support of an LR curve that complements the AS curve) a ride performance that makes these newer bikes similar in feel to the older Magic Link bikes is part of what makes your new linkage, per the optimisations you have sought, interesting. That I am somewhat disapproving of those optimisations, ought not be something that bothers you. If I were you I would want to be taking credit for the unique AS curve and LT curve that you have crafted and how you have been able to emulate the feel of the older Magic Link bikes, without any of the compromises of such a design. And it is clear that the AS curve and LT curve are not accidental so it is strange that you fail to mention them. Meanwhile, people are describing what you have achieved in utterly mystified terms that obscure your actual achievement.
Perhaps, you imagine there has to be a more dramatic "triggering" condition than that, where mechanical effects arising from chain tension are removed before the suspension can start to move back to SAG. Well, I take it we would agree that ceasing pedalling, at least, will trigger the return to SAG even if we are inclined to make some additional points about this. I think you may be sadly disappointed in the hunt for some mechanical force, somehow exerted though chain tension, that could hold the suspension in a topped out state, for a linkage like this, except insofar as that chain tension leads to a surfeit of anti-squat. You must already be aware that believing in such a force or effect is totally inadequate. You must be able to explain how it works in sensible terms before you can expect anyone else to accept your account of things. I welcome such an explanation but so far I haven't seen one.
Remember the old argument about 4 bar vs. faux bar. The faux bar was indeed a 4 bar linkage in the general sense, BUT, it was a 2 bar in terms of axle path, basically a single pivot.
So if you are trying to evaluate this in terms of a 6 bar linkage, you will get seriously flawed results.
Which brings me to vrock. I have pointed out to him some serious errors in his analysis. He prefers to believe his answers. They do not reflect the way the bike actually behaves.
Is this not your quote
" Also, a claim is made that chain tension from pedalling can hold the linkage in a position that keeps the rear suspension in a fully extended state. First, that claim doesn't amount to much because for a bike with a properly adjusted SAG, there is no amount of chain tension (that can be generated by a rider) that can somehow lift the bike up and hold it there when its natural tendency on the contrary will be to return to SAG"
Are you not there basically saying that what I am claiming cannot happen?
Chain tension, pedaling effort, yes. They affect the bike much more like the Magic Link than a traditional AS effect. No, there is not an additional degree of freedom, but the similarity is in the way the horizontal forces on the chainstay, fore and aft, modify the spring force. This is just not possible with any conventional design, or any AS or LR curves.
I do mention LR, but in a way that matters more to the rider. The LR, in isolation, is meaningless. Just read how many bike tests mention they wish the shock had a larger or smaller air volume. This is ALWAYS because the LR and air spring curve are not well matched.
So instead of using LR as a defining factor (it plays a small part), I am using the wheelrate, which is the actual force to compress the back whelel under varying conditions. This is a performance parameter that really matters. And the Missing Link allows me to modify that for conditions in ways that conventional suspension cannot.
You are correct in your point that some of the parameters I am using are to help it emulate SOME of the desirable characteristics of the Magic Link. The pedaling support of the Missing Link does allow me to have a falling rate for the first part of the travel, for exceptional small bump performance, especially when combined with the Missing Link's "softening effect". But the Missing Link goes further. It allows for full extension, for maximum geometry change while climbing and maximum stiffness, for absolute hardtail effect on a smooth climb.
So, while you and vrock have some idea of some of the effects happening, you are the ones obscuring what the linkage is doing, by trying to describe in in conventional terms, with conventional measuring sticks. Vrock, by his own admission, is also using a scaled photo (and a canned software program), which is fun for shiits and giggles, but hardly worthy of a serious engineering discussion in absolute terms, which was how he was presenting it.
Open your mind a little bit. Please do the free body diagram for yourself and get back to me.
I am using that horizontal force to trigger the release instantaneously. As the wheel hits the face of the bump, the horizontal force pushes the wheel and thus the CS, to the rear. That force is translated through the Missing Link into the top of the shock. In one of my videos, I liken this effect to a locked human knee, very strong vertically until you kick it in the back of the joint, at which point it buckles immediately. Same exact effect.
www.youtube.com/watch?v=uh44UMTOmB0
Please keep in mind
1) this is based on a highly inaccurately scaled photo
b) it is a "conventional" analysis, i.e. has no bearing. It's in a vacuum
3) canned software with limited options for open mindedness
It's a good guess, but not quite right.
There is one comment that needs to be clarified. You seem to want to separate chain forces form AS. There are, in fact, the exact same thing. Right??? AS does not exist with chain tension. More chain tension,= more AS.
Of course you can have chain tension without AS, but not the other way around.
You also make a comment about the extensive effect serving an ill-considered purpose. Would you not agree that a bike with 64 degree static HT angle might climb better with a 68 degree HT angle? Do you consider that ill-considered ?
To use the horizontal forces available to me to manipulate the suspension for better geometry when needed and better spring forces for various conditions.
One important aspect of the Magic Link was to use those force to help create the same "knee action" effect that I described earlier with the Missing Link. Using the horizontal forces to modify the geometry and spring rate. The fact that I figured out how to do it by inputting those forces into the upper shock mount allowed me to
A) eliminate the aux spring/shock
2) make it lighter/stiffer/cheaper/easiertosetupunderstand
c) have infinite spring stiffness when needed
4) have more geo change when climbing.
In return, I gave up the extra degree of rearward axle path and the series effect of the 2 springs in action, both of which were a benefit on square edge bumps. Which is why you will see a Tanrum DH bike with the Magic Link. For pure bump performance, it can't be beat.
note: for those not knowing what is at issue here or confused by how the same linkage might (without error) be described in different terms (and with differing apparent bar counts) all that matters really is i) are well all talking about the same thing as we use these terms and ii) do we all recognise the way wheelpath will be governed given the particular form of a linkage assembly (once we can be sure we are talking about the same linkage assemblies despite any terminological peculiarities).
Please do not wait for me to prepare and consider any free body diagram. I am a well informed lay individual with a special interest in bicycle suspensions not a mechanical engineer.
It it were a 6 bar linkage, the 6th bar would have some effect on the wheel path, and therefore any anti-squat/anti-rise characteristics the suspension might have. But it does not. It can go away for those purposes.
To call this a 6 bar is just as inaccurate as calling a simple pivot bike with SS/rocker driven shock, a 4 bar. For shear definition, it is a four bar linkage, however, in terms of axle path, etc, it is a 2 bar linkage.
This is not my authority. Standard engineering terminology that has been around for eons. I'm a mechanical engineer.
So, without the chain tension, there would be no traction, no acceleration. If the tire loses traction, so must chain tension be lost, as well as acceleration. In a way that is linked mathematically and can be calculated. The problem is that these terms get tossed about interchangeably. And while they are all inextricably linked, the effects by one force on another have infinite possibilities for modification.
So, once you know what the force is at any given point, whether it is chain tension, acceleration, torque on the crank, etc, you can calculate the forces anywhere else in the system with my beloved free body diagram. It's a lot of work.
The best term to use might be acceleration. This is a good representation of what happens will climbing. At a constant riding speed, you are accelerating uphill. The rate of acceleration is directly related to the stiffening effect of the Missing Link. This is also true of AS, just in a different way.
This is EXACTLY what is does. In fact, you don't even have to stop pedaling. If you pedaling effort is reduced the sag will gradually and proportionally increase. As you reach the top of the climb, the sag will return to static level even as you keep pedaling to finish the climb. the stiffness will remain (until you hit a bump). But we no longer require an exaggerated steep geometry, so we let it come back to static for level ground.
The triggering effect occurs whenever a bump is encountered, whether on a climb, flat or descent. It is most pronounced at full extension, where it must be to absorb the bumps in a steep climb, so you can still have max steep geometry, max pedaling stiffness and yes, max bump absorption and traction.
"You seem to want to separate chain forces form AS. There are, in fact, the exact same thing. Right???"
Anti-squat (on a bicycle and most motorcycles) originates with chain force/torque/tension but they could hardly be the same thing. For a chain driven vehicle anti-squat can always be broken down into two dimensions or components - the chain based component, which while necessary (it is where all motive force comes from for a chain driven vehicle, obviously) as a condition for the existence of anti-squat is not normally the key determining factor of actual anti-squat force, and another component based solely on vehicle and suspension geometry and kinematics that is both key to the determination of actual anti-squat force and must be present in order for chain force to become an effective component that is partially determinative of the actual anti-squat profile of a vehicle.
Very briefly, without traction and a spinning wheel, which are clearly not 'chain tension', but rather its transformed result (if we are lucky and things go to plan) we have no squat or anti-squat of any kind or in any magnitude and no way for the chain component to exert any effect - chain torque without traction doesn't generate anti-squat just a wheel pointlessly spinning on the spot and anti-squat is irrelevant in that situation. The implications of this are not only that we need traction and acceleration, i.e. a motive vehicle and not just chain tension, before we can meaningfully start talking about anti-squat, however. On the contrary, what this amounts to is that the vehicle geometry and kinematics based component, which is straightforwardly and independently calculable without knowing anything about chain tension must always be there as a background, i.e. modelled in terms of a fully realised moving vehicle with a rotating wheel driving forward and pushing against the vehicle chassis with that driving force mediated through the particular suspension linkage geometry, for the chain based component to ever gain any purchase or come to have any definable effect on the behaviour of the vehicle during powered acceleration.
So, no, AS and chain forces are not the same or at least it is misleading to talk in that way about AS, even granting that the direct relationship, increased chain tension = increased AS (magnitude) holds (where traction exists). AS is a complex phenomenon that gets distorted by trying to reduce it back to its origins. That it originates in chain force, like driving force and squat, as well, doesn't mean that it is validly describable within those terms. That point of view leaves out the key role of the rotating driving rear wheel and vehicle kinematics which are the conceptual centrepiece of a comprehensive account of AS (not only for chain driven vehicles but also chainless powered vehicles as well).
In the next paragraph, you state, " chain torque without traction doesn't generate anti-squat". This is sort of true, except that there is NO chain torque without traction (excluding from friction) so thus no anti-squat force from the ground wheel interface, (although there still is an AS component from the direction of chain pull).
For any given system/suspension layout, would you agree that you can calculate the anti-squat force once you know the chain torque?
And we're not talking about chainless vehicles here, which obviously have no chain torque.
On another note from an earlier post, I apologize. I tried to correct my post but couldn't. From a classical mechanical engineer perspective, it IS a 6 bar linkage that drives the axle path. I made the obvious error of not including the ground link (frame) in my count.
But here are the classic versions of 6 bar linkages, including the Stephenson:
www.rehab.research.va.gov/jour/03/40/1/images/jinf01.gif
Take a look and you can see critical differences. The main one being that, in the linkages shown, there are 3 joints attached to the ground link and only 2 links which do not attach to the ground link at all. In the Missing Link, only 2 links attach to the ground link, the Missing Link itself and the main rocker. There are then 3 different links which are NOT attached to the ground link: the chainstay, the seat stay, and the link that drives the shock from the rocker. So, while it is technically a 6 bar linkage, it is not in the same genre as the Stephenson linkage.
"...although there still is an AS component from the direction of chain pull..."
I'll concede that. I am being a bit over zealous in some of my formulations.
"So, while it is technically a 6 bar linkage, it is not in the same genre as the Stephenson linkage."
I have looked very closely at the Missing Link and can see no reason it wouldn't be considered a Stephenson I linkage, viewed from a classical mechanical engineering perspective.
2) Bearing friction is negligible. How can affect it in reality? You can take it in account for the most realistic calculations but the influence is minimal and the complexity will be very high.
3) If you don´t have the Linkage program, how can you say this? You can model the Missing Link properly (6 bar). The program gets the instant centers of rotation to get the kinematics. With a CAD you can obtain very accurately results. It also analyzes the entire system not every linkage independently, which could give completely different results and therefore conclusions far from reality.
And following Gruble's criterion it can´t be a 5 bar. You're not considering the frame. With 6 members and 7 joints you got 1 freedom degree, with 5 it isn´t possible. So this you say is a big mistake.
Anyway, it would be good that you publish your calculations and graphics to end this controversy, if not always remain the doubt that can be simply marketing.
As for #3, I've played with the linkage program. When I say played with, I don't mean that in a disparaging way, but it is a bit underpowered. I also find that software like that can lead to lesser understanding of the system, with more tendency to make errors of assumption or data entry.
It is a 6 bar linkage.
The other change is the low volume air can. This is to provide a rising rate when the liknkage goes linear for the last half of the travel.
Aside form those 2 items, I can use a much lower cost shock. I may even offer my own, even though that is a high market risk.
That's why I posted videos of pedaling through that rock rock at low speed/high effort. To show that it is active while pedaling. When needed. But then on smooth climbs, infinitely stiff and at full extension if the climb generated enough effort.
I specifically quizzed RC on any feeling of pedal kickback or feedback. He said he never felt any at the beginning of the ride and never even thought of it after. And this ride was ALL rock.
Pivots are all standard bearings.And so far, very good life.
forums.mtbr.com/attachments/all-mountain/1180638d1517370623-new-innovative-suspension-tantrum-cycles-any-thoughts-black-lizard-s.jpg
Want to isolate the pedaling and braking from the suspension? Minimize chain growth and move the axle (more-or-less) perpendicular to the chain tension under pedaling. Tweak the leverage curve so that (when coupled with a properly matched and tuned shock) you have the highest leverage in the sag position - giving you the best rear wheel traction. I like lower leverage curves because the provide a larger tuning sweet-spot and are more forgiving of heat, but they come with a slight weight penalty and more sticktion. (...which the higher leverage in the sag zone mostly negates)
A Dual Short Link design (VPP, DW Link,etc.) gives you the most control over the leverage curve and axle path, plus lots of options for shock location and orientation. A Single Pivot with a linkage-driven shock can work just as well, but can be trickier to get the right leverage curve without taking up the whole front triangle. The big advantage of the Single Pivot though, is that the pivot itself can be significantly stiffer and more reliable. One large axle with large bearings will always be a better choice than 8 smaller bearings - all trying to work in parallel, but subject to manufacturing tolerances.
Unless your bike has rear cantilever brakes, there is no reason to ever put a pivot on the chainstays, near the dropouts. For some reason, almost 30 years ago, the idea that maintaining the relationship between cantilever brakes (this was pre-V-brakes!) and rims by connecting the dropouts to the seatstays got conflated into the idea that the "Horst-Link" magically isolates braking forces.
Nowadays the "Horst-Link" bikes are only useful for seeing which brands actually employ suspension engineers vs. designers who send .jpgs to China. More pivots = more flex = more weight, shorter service life, etc. If you really think you need an extra pivot to achieve the magical axle path you've dreamed up (you don't. you are wrong) just stick it up near the bottom bracket, (Dual Short Link) and at least you'll have the benefit of a stiff, one-piece rear triangle.
*I'd suggest buying a second Solidworks license for RC himself, but after 25+ years of being completely wrong about bicycle suspension, I don't think he's interested in actually learning anything.
You like Dual Short link bikes. That's awesome, so do I! but that doesn't mean they give the designer the most control. A horst link and a short dual link have the same number of pivots in the rear, four.
Why can a single pivot be stiffer and more reliable? just because there is only one? Why not use those same stiff pivots in 'more complex' designs? this really doesn't make much sense. Sounds to me like you have some preconceived notions about linkage design, bearings, and how linkages work that might need be let go.
Am I sold on this as the new best? nope. But I want to at least ride it before I declare it to be marketing BS.
Keep in mind that the lateral and torsional stiffness I'm talking about is not some idealized property that you want to beef up just for bragging rights. It has very real effects on the operation of the suspension and durability of the design. Flex effects bearing alignment and adds friction. Since most pivots in a bike's rear suspension only use a few degrees of motion when in operation, a tiny bit of misalignment gets amplified as the same section of the bearings/bushing take all the damage.
This is why I favor a single pivot design. (...with a linkage driven shock, of course) One big axle with big bearings will always be easier to keep in alignment than the 8 (or more) pivots in a Dual Short Link or Horst frame. It's also much easier to get the desired stiffness and strength in the bearings and swingarm. Not as sexy or patentable, and getting the desired axle path and shock placement are trickier, but much more practical.
But you know, '09 SW is actually pretty good. And the information is there to calculate whatever you want. I prefer to do do direct analysis than rely on canned software, at least for the kinematics. You develop a tendency to understand the answers much better. Like when your math teacher made you derive equations.
In the end, the math doesn't matter if it doesn't ride well. If it doesn't do what I want, what I say it will do. And it does. Do you think I would come out here and have RC rip me to shreds for wasting his time? I don't mean that in a bad way, but the man has been around bikes for a long time. I may not agree with everything he's ever said, but I knew he'd give me a fair shake and tell it like it is.
You're kind of missing the point (or the link, HA) to the whole design. I DO NOT want to isolate the suspension from pedaling forces. Exactly the opposite. But the key is, how to use those forces. For what part of the travel? and how much? I chose to use those pedaling forces as a proportional measure. Certainly on a climb, you would want some increase in rear stiffness, right? At least to combat weight transfer to the rear? Can we agree on that?
And what about geometry? All things considered, would we want a steeper geometry for climbing? Especially with a 64 degree static HT?
So, my goal was to use the pedaling forces proportionally, to provide these benefits WHEN NEEDED. Again, that is the key. Those goals cannot be accomplished with dual short links, or any other links. They just do not use the forces in the necessary way. Because they can't. The layout and design of the linkage does not allow it. If it did, they would.
I don't understand why you think it is 'easy' to get proper alignment on a linkage-driven single pivot, but 'hard' to get it on a 4-bar. It's the same amount of effort. Many single pivots bikes (kona, scott, ect) have the same number of bearings in their single pivot design as a horst link. Or do only the pivots along the chain stay count toward flexing on the rear triangle?
I agree that Dual Link offers some nice advantages, (and I think this missing link might offer it's own set of advantages) but i don't think that bearings on the chain or seat stays are bad or a poor choice.
Second, the rear brake is not acting on the rear wheel in a vacuum. Yes, there is some rotational force acting on the caliper/seatstay/axle, but the greater force is the wheel acting on the ground, and vice-versa. The second greatest force is the rider's weight. Floating brake calipers, Horst Links, and rear pivots concentric with the rear axle are all - as they say - jive.
There is no way for a brake - acting only on the rear wheel - to lock out a rear suspension system.
I understand that for many people this seems counter intuitive. It took me a while to figure it out, too. Luckily, I started playing in mountain bike suspension in '89, and wandered into a career in engineering. Still, I didn't really get the idea that axle-path tricks are mostly bullshit until maybe 5 years ago.
It's not the easiest read, and there are a couple points I quibble with, but the Path Analysis site has some great info. Start with their "mirror bike" thought experiment, and dig in from there: members.home.nl/vd.kraats/ligfiets/pa/pa34.html#TheNaturalMirrorBike
Would you care to explain this in light of your above comment that Floating brake calipers are jive. You might also ask J Tomac how it kept him from ejecting over the bars on his lawill bike or how the Giant DH team did a back to back test at Big Bear before a big national. They loved it, but decided to race without it to save weight. After one practice run, they all came back and put it on for the rest of the weekend, even though they didn't want to. Oh, yeah, maybe ask Fabien Barel and Tracy Mosely why they lugged that useless thing around winning world DH championships.
If that doesn't work, try some free body diagrams with an open mind.
cheers,
b
Even if it weren't gimmicky as fvck then it's still ug' as FAAAAAAACK! Everyone loves a superficial pivot or two on their concraptions nowadays though don't they? Just needs a bright yellow Girvin up front for a full deuce. Just lookin' at it makes me wanna hissy. :/
forums.mtbr.com/all-mountain/new-inovative-suspension-tantrum-cycles-any-thoughts-1009862-2.html
You have to judge for yourself whether the unique linkage characteristics and suspension behaviour, described on this page and the Tantrum website, are beneficial for your riding and whether any gains outweigh the costs.
www.youtube.com/watch?v=Qn1Hr-u_XJA
*ba-dum diss*
Link 1: Above BB pivot to Front CS pivot
Link 2: Front CS pivot to top of SS pivot
Link 3: Top of SS pivot to Seat Tube pivot
Link 4 is static: Above BB pivot to Seat Tube pivot
The additional link drives the shock
Correct link count:
Link 1: The seat tube (often called 'ground')
Link 2: CS
Link 3: SS
Link 4: The rocker link
Link 5: Rocker Link to the shock
Link 6: CS to the shock (with a stop at the seat tube along the way)
This is a pair of linkages. There is a 4-bar (Seat tube, Rocker, Rocker to shock, CS to shock) (or Link1, Link4, Link5, Link6)
but there is also a funny 5-bar (Link1, Link6, Link2, Link3, Link4) It would take me a bit to figure out how to analyze the kinematics.
So, yeah, something I've never seen on a bike before. I'd like to ride it too.
The links connected to the eye of the shock, when in line is in a toggle position and effectively locks out the motion.
Cool design though aside from the paint job seems to be quite complex with the number of pivots.
I modeled the shock as a set of sliding links. For position analysis, can ignore those links and could do an analysis of the moving links.
It is great when engineering and hobbies collide!
Pffft; a Red Mattoc with that yellow would be dope!