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Interbike 2015
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If you’re a Vital MTB regular, you’ll remember seeing the Tantrum Meltdown as a prototype at Eurobike 2014. Since that time, the company has evolved a bit more and will enter production with direct-to-consumer May 2016 availability on this 2017 model. The bike is called the Tantrum Meltdown and will be available in 27.5, 27.5+ and 29-inch varieties. The 27.5 model sports 160mm of travel, a 66-degree head angle, 73-degree seat angle and 13.2-inch bottom bracket.

What makes it super unique is the suspension system. Due to the lower link placement, it is claimed to be far stiffer under pedaling than the vast majority of trail and all-mountain bikes. Yet when it hits a bump, it’s allowed to open up, giving the bike some traction. The leverage curve has a falling rate from sag to 50%, and from 50% on it becomes much more progressive. It made us do a double take. Watch for more in 2016.

Credit
Brandon Turman
Related:
Interbike 2015
Tantrum
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2016 Trail and Enduro Bikes at Interbike
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18 comments

c50 received 10155046990160862 1496571885
Axa
8 years ago
Nice update on the website Brian!
The new video should make it easier to understand the benefits the Missing link can offer compared to most other suspension patents on the market.

Will Tantrum go with the new Boost standard on all frames?

Is Outburst the model that will be 27+ compatible

Cheers Gunnar.
c50 received 10155046990160862 1496571885
Axa
9 years ago
I notice internal cable routing in the top tube for seat post remote. Do you have any plans on routing the rear brake and shifter internally in the down tube? Or is the recessed lower shock mount not allowing that?
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tantrumcycles
9 years ago
Axa, we're trying a few different options on cable routing, including DT. The reality seems to be that nobody really likes it from a practicality point of view. It would be nice to cleanly offer both. The shock mount isn't a problem, the DT is wide enough.

One set of the internal guides in the top tube can potentially be used for the rear derailleur. It could then ride on top of the SS, or inside.
c50 linkage solo 1481239778.jpg?VersionId=7robi1GfgPWYZL9UIUsVN DUGO
tantrumcycles
9 years ago
A number of questions have come in from this thread, both here and from my email, so I will try to address them here:

bearings. four main reasons we don't want more bearings:

1) weight. Bearings weigh, unless you go ceramic, which are expensive. BUT, offsetting the weight (and cost)are the lightest possible shock, no remote lockout needed. This also helps maintenance, less to go wrong with the shock. I also paid meticulous attention to weight when designing the frame, a medium (18"), with shock (as shown), weighs 3.54k, or 7 lb, 13 oz, which is pretty competitive for a 160 mm bike. Production frames will come in over 1/4 lb (140g) lighter, so a frame and shock will be 7 and 1/2 lbs.

2) bearing slop, especially in the rear CS

Really, this is the number one reason. The main reason is that these bearings are not really designed for the side load we put on them. On the Tantrum, only two sets of bearings cause cause rear slop, the CS bearings. And the links connecting those 2 sets of bearings are literally as short as possible. On a typical dual link bike (you know the designs), there are 4 sets of bearings that can develop play in the rear, always connected with longish links.

The rest of the bearings on the Tantrum are actually used for the correct purpose, mostly pure radial load, so bearing life will be much better. In addition, one of the sets of bearings are used for the upper shock pivot, adding suspension response and eliminating bushing slop at that point.

3) maintenance hassle

At some point, all bearings must be replaced. Fact of life. To make this easier, NONE of the bearings are pressed into the frame, just the links, and they are all readily available


4) cost

guilty, but, again, offset by the ability to use a much less expensive shock
c50 received 10155046990160862 1496571885
Axa
9 years ago
To that makes more sense then any suspension on any trailbike. But it's equally easy to understand how both that mental paint job, and the simply ingenious linkage can cause a mental Meltdown to anyone who don't get it.
So be sure to take a close look and a thorough read at http://www.tantrumcycles.com/ before geting judgemental!
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tantrumcycles
9 years ago
thanks axa. And I apologize for the rudimentary state of the website. We will have production bikes in April and the website will be a work in progress in the meantime. Expect a lot more pictures, action videos, etc. Hopefully it will all make it easier to understand. But nothing tells it like the ride, so maybe a few sneak peak test rides might appear here and there?
c50 tetten 120
Aginato
9 years ago
Since the stiffening of the suspension mainly seems to rely on chain tension, I wonder how easily it will "open up" while pedalling?
And I'm under the impression the system will generate quite a bit of pedal kickback during this "opening up"?
I'm guessing it all depends on how the chain tension / pedalling force stacks up against the impact force of a bump.

Seems like an interesting bike / suspension system.
And not relying on the LSC of the shock to sort out pedalling performance has its advantages. I'd love to try one.
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tantrumcycles
9 years ago
hi Aginato,

There is a critical difference here as to how the suspension responds to chain, bump and braking forces. ALL other suspension designs (excluding "brain" type shocks), rely on some form of anti-squat produced by a relatively high pivot (whether virtual or real). This anti-squat force acts through the chain tension to pull the wheel forward and resist rotation of the links into the travel.

The "missing link" on the Tantrum modifies the force on the shock by stiffening it due to chain and pedaling force, as well as SOFTENING it due to bump and brake force. So the effective spring rate felt by the rider is continually being modified by the link, according to the forces acting upon it. So, it's always a balance between how hard you are pedaling vs how hard and big the bumps are. Pedal up a steep, smooth granny gear climb and if you are sustaining a higher effeort than you can on level ground, the suspension will stiffen proportionally.if you set static sag at 25%, you will notice it is at 15% for a moderate grade, all the way to zero percent at a very steep grade. You read that right, under max effort, the rear shock will slowly extend until it is topped out and it will stay there, giving you a completely rigid suspension and steep climbing geometry......until you hit the bump/root/log. At which point, by nature, you must back off the pedals a tiny bit, while the bump encourages the link to rotate the opposite direction and ASSISTS compression of the shock.

Will the suspension top out during max effort on level ground? No, you simply cannot pedal hard enough on level ground to rotate the link with enough force. BUT, you can pedal hard enough to still feel like the suspension is virtually locked out. Again, until you hit the bump.

NO lockout ever needed. And you are correct Aginato, every bike/shock on the market still carries a bit too much LCS. This is a compromise to dampen some of the remaining suspension motion present. But not ideal for small bump compliance. With the Tantrum, I am able to dump all of the unneeded LCS, so the bike is very plush over bumps, but pedals like a hardtail in smooth stuff.
c50 received 10155046990160862 1496571885
Axa
9 years ago
Since nothing can beat a coil shock for small bump compliance / sensitivity . And no LSC, platform, lockout, piggyback or "brain" camber or electronics is needed - It leads me to wonder if a light and simple (titanium spring) coil shock could be a even better match for the Trust Vector suspension then an air shock? Or does the trust vector forces make this suspension even less sensitive to shock stiction?
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tantrumcycles
9 years ago
You'd be surprised how much air shock "stiction" is a product of compression damping. Coil shocks have compression damping too, of course, but acting on a much smaller seal surface area. You could probably get a small improvement in small bump sensitivity with a coil shock, but, and this is big, the leverage ration and how it changes, was specifically designed to take advantage of a low volume air shock rising rate. A coil shock would be difficult to match.

Just for fun, I took all of the damping out of an air shock. There is no way you would say it had stiction. It was WILDLY active in both directions. So, normal damping is good and necessary, but doesn't really add to much of a stiction feel, once we get rid of platform and excess damping.
c50 received 10155046990160862 1496571885
Axa
9 years ago
Good explanation Brian.
It's easy to understand the linkage must be very sensitive to small bumps since the initial travel got falling rate. I guess the rearward axlepath help on "plushness" to. And certainly the lack of any need of platform-valve that need oilpressure to react and open up on bumps.
And no need for complex separated dampening settings for high / low compression and high / low rebound, to try to find the best compromise, should make the suspension noticeably easier to set up then on anything but the most advanced and expensive of today's electronic alternatives.
c50 received 10155046990160862 1496571885
Axa
9 years ago
I've been riding my Magic Link bike hard for 5years without any bearing issues even it got 5sets. I have not heard anyone complaining about either.
Shock bushings on the other hand was another story as on any bike with the standard cheep unsealed alu bushings.
Both bushings and most of the 5 sets of pivot bearings on my previous bike, a Scott Genius, fell apart within 2 years due to being badly underdimentioned and poorly sealed with standard non high pressure resistant RS seals, and lubed for a life in high rpm appliance instead of moist and harsh impacts..

Bearing and bushing life and numbers of pivot points do not have anything in common at all.

To last in anything but dry conditions bearings needs proper High Pressure seals and/ or grease that are resistant against uncarefull us of waterhoses, high pressure washers and submerging. And that only works if dimention and type of bearing is suitable for the application.

Most slow moving bearings can be Full Complement type bearing - Maximal possible amount of balls/rollers since there is no cage needed to separate the balls/rollers as in bearings in higher rpm applications.

To me it looks like the shock bushings might be replaced with proper bearings on the linkage side? And a rubber-bushing mount against the frame downtube?
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tcmtnbikr
9 years ago
falling rate to 50% and then progressive rate. Hello, that's called wallow!
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hamncheez2003
9 years ago
In theory, the wallow is counter-acted by the pedaling forces; that funny link keeps it higher in the travel while on the gas.
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tantrumcycles
9 years ago
hamncheez is mostly correct. The funny link (missing link) keeps the bike higher in the travel when on the gas, to the extreme of riding at zero sag during a max climb effort. You could never use the rates we use on this bike with a conventional suspension, as it would indeed wallow.

It's important to note that the "falling rate" occurs partly due to the assist in shock compression (due to bumps) from the missing link, therefore, no bumps equal no falling rate.

make sense? some?