PIVOTAL MATTERS
All great engineering is based on simplicity. Find the most elemental solution possible, refine it, reduce the complexity, and you’re done. And that’s how our mp4 suspension has evolved.

Some of the other guys would have you believe complexity is a good thing, outfitting their designs with so many pivots and bellcranks it’s a wonder the wheel can move at all. We’re not convinced.

A simple design requires fewer parts, which takes less material and structure, which means less weight. And it also means fewer bearings, eliminating weight while reducing unwanted movement (every bearing has a little slop—the more bearings you have, the more slop you get).

Our mp4, mp3 and mp2 designs rely basically on a single primary pivot, located just above and behind the bottom bracket centerline. Because this single pivot takes most of the load we don’t need a plethora of heavy bearings—just this and two other really, really good ones (where the seatstays connect to the bell crank and where the bell crank connects to the frame). And because everything happens at this one primary pivot, we can place it in such a way that it minimizes braking influences, reduces pedal kickback and unwanted movement due to chain tension. Nice!

The seatstay pivot improves geometry with a consistently near-vertical axle path throughout the wheel’s travel, for better suspension movement over tiny stutters and big hits alike. And structurally, the bellcrank helps shore up the rear triangle against lateral movement and improves torsional rigidity so the rear wheel stays in plane—there’s no wandering or fishtailing because the axle’s so well controlled.

Even though our main pivot is located in the same BB location on all our mp designs, we can tune leverage rates with bell crank lengths, bell crank pivot location and shock position. Our mp2 and mp4 XC designs offer a very slight rising rate in the first 40% of travel, and then it’s linear for the balance of travel. This means you don’t get a sudden ramp-up as the suspension compresses—there’s nearly linear response in the fat part of the travel curve, for supple action over stutters and medium hits, with a bit of ramp-up as you approach the travel limits and a nearly bottomless suspension feel that’s ideal for short-travel XC designs like Dakar XCR 29ers, the XCR Race and the XC Comp & Sport. On our longer travel XCTs, 650Bs and AMT, our mp4 Trail design offers a much more progressive leverage rate. This means the rear shock can be tuned more linearly (like a coil spring) and pumped to lower pressures for a smoother, more plush ride without bottoming.

THE LOW LEVERAGE ADVANTAGE
We’re huge believers in low shock leverage ratios – all our mp designs have an average wheel-travel-to-shock-stroke ration of 2.65:1 This is really important, when it comes to suspension smoothness and durability.

For one thing, you get better performance from the shock with a lower leverage ratio. There’s less force being taken up by the shock, which reduces stress on the shock internals. And because you’re employing more of the shock’s throw for the fat part of the travel curve, the suspension action is much smoother and better controlled.

A low leverage ratio also means you don’t need super high spring rates, which translates to improved shock sensitivity. External rebound and compression damping adjustments can be made in much finer increments, which wouldn’t make an appreciable difference on more leveraged designs. You can make better use of the shock’s tune-ability (and today’s shocks are impressively tuneable).

What’s more, a lower spring rate lets you employ a physically lighter coil spring, or in the case of air springs you can use less pressure, which improves shock sensitivity and vastly extends seal life.

DYAD SUPREME (Xenith T2, Dakota d29 Team)
30% super-high modulus M40 carbon fiber, 70% high modulus M30 carbon fiber. Reducing the M40 percentage to 30% and blending the M30 with the M40 increases frame weight by about 7%, but increases shock damping for a more comfortable ride.

Key point is that we’re not just using “high modulus” as marketing verbiage to define all our frames, while hoping you to have no idea what modulus is all about. There’s a place and a reason for high modulus, and there’s a place and a reason for mid-modulus. Describing anything as “mid” may run contrary to the advice of the Marketing Department, but mid-modulus fiber, especially when blended with high modulus can still be light and stiff with some degree of damping and flexibility for a supple, comfortable ride.

R&D/MANUFACTURING
We’ve designed, built and ridden carbon fiber monocoques as well as tube-and-lug carbon frames, and our monocoques were always lighter, more durable, and simply rode better. Materials overlap in lugged frames which concentrates stress at the bonded joint. It also weighs more and contributes to a deader frame feel. Monocoques are completely unified. Stresses are distributed over a greater potion of the frame structure, making for a lighter, stiffer, stronger frame and one that rides with a snap and liveliness that’s its own reward.

A monocoque’s structural integrity relies heavily on the lay-up schedule, the master plan for the location of each and every carbon ply. We start with Finite Element Analysis (FEA) software that visualizes where structures bend or twist and simulates the distribution of stresses and displacements, this allows us to design, refine and optimize the materials and lay-up before cutting molds and burping prototypes, which are then relentlessly fatigue- and deflection-tested for every frame size. Failures get kicked back to the lay-up room for some material massaging and ply re-arrangement until they’re good to ride.

Then we suit up for the hard part of our job. The ride! We ride and record, ride more and record more. We enlist our pro riders for evaluation and comment. The beauty of carbon is its ability to be easily tuned by manual manipulation of the plies, like tensioning a drum head or guitar string for absolutely perfect ride quality -- the just-right balance between stiffness and resilience, the ability to feel the road.

It’s important to remember every carbon frame is handmade. There’s a skill and artistry to accurately applying small squares, rectangles and triangles of carbon fiber according to the schedule our engineers assign. Just because it’s hidden beneath a cosmetic layer of 1K, 6K or 12K weave doesn’t mean it isn’t there, and it’s no less skillful or significant than precision welds or brazing work.

These carbon fiber swatches are laid up on a silicone mandrel, one at a time, in an interwoven and overlapping pattern. As each section is complete the silicone mandrel is removed, each section is joined to the others, and expandable air bladders are run through the frame. The frame goes in a steel mold, the mold goes in an oven, bladders are pressurized, the oven is heated to melt and disperse the resin, and then the whole thing is cooled to harden and cure.

All these steps are necessary to ensure compaction, which is where it’s at for carbon fiber structural integrity. That’s why we’ve taken monocoque molding technology to the next level with our Near Net Molding technology (featured on the 2012 Xenith SL and the Dakota dXC Team frame kit). Near Net Molding is a revolutionary process utilizing air bladders and a polystyrene pre-form core that recedes as the oven heats, assuring an interior that is “near net” in finish, without the wrinkled fiber or resin pooling common in most of today’s carbon frames. Every gram of resin has been compressed, every length of fiber has been flattened and aligned.

After hours of hand finishing, before heading on to the painters and clear coaters, EVERY frame is weighed to make sure it’s neither resin rich nor resin deficient. We also measure the stiffness of each frame in 6 critical areas as a check on lay-up production, guaranteeing every frame we produce will deliver the ride qualities we defined and demand.