Jamis Tech

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SIZE SPECIFIC TUBING

The benefits of a properly fitted bike have been recognized for years. It is essential for injury prevention and maximized efficiency. And it is the primary determinant in assuring the greatest comfort and enjoyment while riding.

Our first road bikes introduced in 1988, the Quest and Axis (for Jamis history buffs, this later became the Eclipse), were designed in consultation with Bill Farrell, inventor of the first bike-sizing tool, the Fit Kit. Back then, bike companies generally plotted a single geometry on all frame sizes: the blow ‘em up or shrink ‘em down solution – lazy, cheap and thankfully long ago obsolete. We learned from Bill early on how to tune our frame geometries and specify component sizing to account for the multiple variables needed for a proper fit for every frame size. We’ve been honing our fits for every bike, every year, ever since.

But fit is a two-dimensional calculation. Stack and reach. How tall, how long, for me? It’s in the third dimension – the SST dimension-- that Jamis continues to make a difference for you.

Slight changes in tube diameter have a significant impact upon performance. As diameter increases, strength and stiffness increase along the length of the tube as well. Whether in aluminum, steel or carbon fiber, we vary the cross-section and sometimes even wall thicknesses to fine-tune the performance and comfort characteristics of each frame size.

SST -- Size Specific Tubing-- optimizes ride quality and assures the lightest possible weight for each frame size. By varying the diameters of the tubing in the main frames of each of our frame sizes (and sometimes even in the seatstays) by 10 – 20%, we can produce a bike that not only fits like a glove and handles precisely, but accelerates and climbs explosively and offers justright compliance for every rider, every frame size.

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THE MAGIC OF MP4

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.

Our mp4 designs rely 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 two really good ones. And because everything happens at this one location, we can place it in such a way that it minimizes braking influences, reduces pedal kickback and unwanted movement due to chain tension

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 bell-crank 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.

But it’s where these pivots are placed in relation to bell-crank triangulation and shock placement that creates the real magic of mp4.

On the XCT and AMT, our pivot placement produces a slight, rising-rate spring curve. 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 mid-travel rigs like the XCT and AMT.

On the shorter travel XCR, we’re pure linear, so the suspension provides a constant pedaling platform from the beginning for efficient power transfer off the line, on climbs and sprints, or when hammering in the big ring on a fire road downhill. When coupled with the naturally progressive spring curve and tune-ability of an air shock, the system is ready to soak up unexpected hits when you miss that line in a nasty rock garden.

We’re big believers in the benefits of low shock leverage ratios. With leverage measured as the ratio of wheel travel to shock stroke. The mp4 design comes in at 2.55:1 on our XCT’s and 2.63:1 on our XCR’s and AMT’s. This is really important, when it comes to suspension smoothness and durability.

For one thing, you get better performance from the shock with a low 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 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 tune-able).

What’s more, a lower spring rate lets you run less air pressure, which improves shock sensitivity and vastly extends seal life.

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JAMIS CARBON FIBRE

Too much of the marketing for carbon fiber bikes is focused solely on the material: how high is the modulus? The rationale being that since modulus is a measure of stiffness, then surely the higher the modulus the better the material! And if higher modulus carbon fiber is more expensive, then clearly it must be better! It ain’t always true. That’s like saying white bread is better for us than whole wheat simply because it’s undergone more processes in its manufacturing.

The truth is, making the lightest, stiffest, most comfortable and most durable frame is not just about what carbon fiber you use, but how you engineer to use it and how you manufacture with it. It’s about what you lay-up and where. It’s about how you compress and set the fibers. Design and engineering are King. Compaction is Queen. And material is the Princess that the media and marketing love to write stories about.

We’ve taken our revolutionary Near Net dual-molding manufacturing process, that utilizes both silicone and polystyrene internal cores to support the frame shape while it is being pressurized within the steel mold, and added a vacuum purge procedure before molding that compresses and eliminates all air between carbon plies. Compaction is absolutely optimized.

Not only is weight reduced while stiffness and strength are increased, but over-reliance on fragile and harsh-riding super-high modulus fiber is minimized. The result is a lighter, faster, stiffer, stronger frame that simply rides better.

The manufacturing process we pioneered in 2009 and once featured solely on our Xenith SL and Team frames has trickled down and is now a mainstay on all our carbon fiber models (excepting those featuring Near Net SPV). Here’s a quick primer on how this works and why it matters.

Once we’ve selected material and resin and determined our lay-up schedule, compaction is where it’s at as far as carbon fiber structural integrity is concerned. If the interior design has constrictions that bind bladders or the bladder material doesn’t sufficiently sustain air pressure, fiber wash or wrinkling in the fiber and pooling of resin is likely. While this is not unusual in most carbon fiber frames today, it represents unnecessary additional weight and a possible stress riser.

That’s why four years ago we took monocoque manufacturing methods to the next level with our Near Net Molding technology. NNM utilizes both removable silicone pre-forms at the main stress points of the frame (head tube, BB, seat tube/top tube) and bladder-wrapped polystyrene cores in the balance of the frame that recede as the oven heats and the bladders are pressurized.

This process produces an interior that is nearly as smooth and pristine as the exterior, what we call “near net”. With every gram of excess resin squeezed out, every length of fiber flattened and aligned, you’re assured the lightest, stiffest, strongest possible frame.

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PRESS-FIT 30 AND BB386EVOM

There are a number of BB standards in the bike industry right now. Here is what you will find on our bikes, and why.

Traditional: The BSA standard. The standard forever. A steel BB spindle, 17mm in diameter, turns within a 68mm or 73 mm shell and upon sealed cartridge ball bearings that are threaded into the BB shell. Not particularly light, not especially stiff (by today’s standards), but reliably durable and definitely cost effective.

External Bearing: The BB shell is still 68mm or 73mm wide and just under 35mm in diameter, but the bearings have been moved outside the BB shell (Shimano Hollowtech II, SRAM GXP, FSA MegaExo). This allows the spindle diameter to be increased over 40% to 24mm and hollowed for a huge stiffness increase with a significant weight reduction. The larger diameter spindle does not compromise bearing size because all bearings now reside outside the frame. The spindle is also better supported with bearings nearer its ends rather than its center.

PressFit30: PressFit30 (SRAM) is a derivative of the BB30 (FSA) system. BB30 increases the spindle diameter to a whopping 30mm for the ultimate in stiffness. But because the BB shell’s inside diameter is also increased from just under 34mm to 42mm, bearing size is not compromised. The challenge with BB30 is that bearings are pressed directly into the frame, leading to durability issues if there are any frame or bearing tolerance deviations. The beauty of the PF30 system is that bearings are housed in nylon cups that are pressed into the frame’s bottom bracket shell. Bottom-line advantages of the PF30 system over BB30? Improved bearing-to-shell interface, greater bearing durability and simplified installation.

BB386EVO: The BB386 EVO bottom bracket design amplifies the benefits of the proven BB30 and PF30 system. It takes the lighter, stiffer 30mm alloy spindle from the BB30 design, incorporates press-fit bearing cups from the PF30 system and marries both to a wider 86.5mm BB shell (which is the same width as on a standard 68mm shell with external bearings). All without changing Q-factor. Why a wider shell? It allows us to increase the diameter of our seat and down tubes at the BB shell a full 30%, for increased stiffness where you really need it. We can also optimize chainstay design with an increased diameter that doesn’t crowd the rear tire.


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STILL KEEPING IT REAL

Back when we started building our first bikes in the late 70’s, steel was the only way to go. Fast forward 35 years and steel is no longer the industry’s dominant frame material, but we still love to work with it and ride it. Why? Hit a baseball with a wooden bat then with an aluminum bat and you’ll know why. You want your frame material to soak up streets and trails, not beat you with them. Not to mention the stuff is durable, can handle nicks and dents and gouges without cause for alarm, and is easily repairable. We like the look of those straight, skinny tubes, too.

Reynolds pioneered the techniques of making butted tubing around the turn of the century, and their 531 manganese-molybdenum tubing was the standard of excellence for many decades. In 1995, Reynolds introduced 853 (and a non-heat-treated version, 631, two years later); the world’s first commercial air-hardening steel for bicycle frames and Jamis was one of the first brands to use it in 1997. Welding steel often results in a 40% strength loss, requiring thick tubing walls as an offset. Not so with 853 and 631. This material actually gets stronger at the weld zones, allowing Reynolds to draw the tubing thinner for a lighter, stronger frame.

Though the high performance and buttery-smooth ride qualities of Reynolds 853 and 631 usually grab all the headlines, our frame building is equally over the top. All tubing is cleaned before being cut, jigged and welded. All tubing cuts are de-burred and buffed before welding. We use heat sinks in the head and seat tubes to control distortion. And our low-angle welding tracks form precisely arced, low-profile TIG beads while dispersing welding heat more widely, yielding a frame that requires less post-welding alignment. Add investment cast or water-jet cut dropouts for great looks and extra strength and you’ve got a labor of love that rides like a dream.

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ADJUSTABLE THREAD SYSTEM

All our frames and forks are tested continually to meet or exceed (in some cases, well exceed) EN standards 14764, 14765, 14766 and 14781 as well as the new ISO 4210 standards. We conduct these tests at our frame manufacturing facilities, but we also use EN accredited testing laboratories such as Intertek and SGS to verify the results of our own tests. If these tests aren’t telling us everything we want to know about our bikes, we increase the loads and cycles, or we determine another way to test. Where current hydraulic testing machines, jigs and hardware aren’t up to the task of emulating some of the forces and impacts our bikes might be subject to, we’ve designed our own.

We relentlessly cycle test for fatigue from pedaling and torsional forces on every single frame size, with deflection tests for stiffness at every point of the frame. Brutal impact tests with massive weights dropped on fixed frames or forks are performed. Then reversed, with weights attached to the frame, the frame hoisted to a given height depending upon product type, then released.

This destructive testing is enormously instructive and important. And it is in continual process. But it’s our ongoing non-destructive testing of frames and forks fresh off the factory floor that’s just as vital.

For our carbon fiber frames, 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. Each deflection test must fall within 5% of the standards our machine and field-testing have established. This weighing and stiffness deflection testing guarantees every single frame we produce meets all Jamis manufacturing protocol and will

deliver the ride qualities we defined and demand.

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FEMALE SPECIFIC GEOMETRY

Though we do make bikes with frame geometry and component sizing specifically targeted for women, not every woman is best suited or fitted on such a bike. We want to be clear about that from the outset. As always, the best advice for buying a bike is to go to your LBS, where you can be properly fitted on a bike. One of our “unisex” sizes just might be the perfect fit for you (though a swap for a saddle with a wider sit-bones platform will likely be recommended). But if you discover that you are, in fact, best fitted on one of our Femme geometry bikes, of which there are many, here’s what you’ll find:

  • Top tubes will be shorter; stems shorter too, with seat tube angles possibly steepened, all to reduce the distance from saddle-to-bar for a more comfortable reach.
  • Head tube angles may be relaxed and fork rake increased to eliminate or minimize the potential for wheel-toe overlap,
  • Bottom bracket height may be dropped so standover clearance is increased and center of gravity is lowered.
  • Handlebars will often be narrower with a shorter reach to the flats and drops.
  • Brakes/Shift levers will often have a shorter reach as well and cranks arms may be shorter for any given frame size in comparison to the unisex version.
  • Saddles will generally be shorter and wider, often with a pressure relief zone.
  • We may even alter the weight and stiffness of our frame materials to better suit a lighter-weight rider (see SST info below)
  • And we make all our Femme bikes in a broad sizing range – from 44cm to 54cm, or 14” to 18”, so you can be assured of finding a Jamis Femme that fits perfectly.

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    ADAPTIVE CABLE ENTRY

    Before electronic shifting was a commercial reality, we were torn on the benefits of internal cable routing. The advantages – stunningly clean aesthetics, no cable stops to chip, ostensibly cleaner cabling systems – were counter-balanced by its chief disadvantages – the extra weight and friction of full-length housing or interior guide tubes and the labor-intensive challenges of installation and replacement. Given our engineering emphasis on performance-first design, we previously outfitted our road-racing Xeniths with externally routed gear and brake cabling. It was light. It was simple. It was easy to maintain.

    But with electronic shifting, it makes much more sense to run everything inside. Attaching and affixing wiring and harnesses externally is every bit as laborious (think cable ties, adhesives and external mounts) as running them internally, where they are much more protected as well. Not to mention, running this stuff inside just looks right.

    Which is why every 2014 Xenith is equipped with our new Adaptive Cable Entry system. ACE allows our frames to elegantly and easily manage the internal routing of brake and derailleur cable housing OR electronic Di2 wiring. Xenith models specified with standard cable-actuated drivetrains will be outfitted with ACE plates with integrated cable stops. But we also include with every bike an extra set of ACE plates for Di2 wiring should you ever wish to make the jump to electronic shifting.

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    ENHANCED COMPLIANCE OFFSET

    A fork’s sole purpose is to secure and steer the front wheel. But there’s a whole lot of engineering involved in making sure your bike doesn’t just steer, but steers “just right”. Not too sluggish. Not too twitchy. And has sufficient lateral and torsional stiffness to hold a line at speed, under turning loads, while still being able to dampen road vibration for comfort and control.

    One of the chief variables between forks is a measurement called “rake”. Rake refers to the curvature or angle of the fork blades as measured from the center of the steer tube to the center of the dropouts. More rake for any given head tube angle will equate to faster steering, with less input required to make the bike turn. But steering characteristics are not determined by rake alone. It is “trail”, a measurement calculated from wheel size, head angle AND fork rake, which tells us how fast a bike will actually steer. More trail yields slower steering, less trail produces faster steering.

    One of our design goals for the Renegae, Endura and Ventura was to increase fork compliance for greater comfort and control, without changing its’ already optimal steering characteristics, lateral stiffness or torsional rigidity. Torsional rigidity in a fork is crucial. A torsionally flexible fork will slow steering on descents and fast corners. There will be a noticeable lag between handlebar input and the bike’s reaction.

    We accomplished our goals with E.C.O. -- Enhanced Compliance Offset. The fork blades on Renegade, Endura and Ventura model’s are swept forward a few millimeters to reduce the angle of the fork leg to the road, which increases vertical compliance for a more comfortable and controlled ride. A reinforcing rib on the inside of the fork legs assures both lateral and torsional stiffness. Most importantly, the “just right” handling traits remain unchanged, even with the more forward bent fork blades, because the ECO trailing dropout design negates the increase in fork rake, thereby retaining the original trail and optimal steering characteristics.

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    TAKING IT TO THE LIMIT

    All our frames and forks are tested continually to meet or exceed (in some cases, well exceed) EN standards 14764, 14765, 14766 and 14781 as well as the new ISO 4210 standards. We conduct these tests at our frame manufacturing facilities, but we also use EN accredited testing laboratories such as Intertek and SGS to verify the results of our own tests. If these tests aren’t telling us everything we want to know about our bikes, we increase the loads and cycles, or we determine another way to test. Where current hydraulic testing machines, jigs and hardware aren’t up to the task of emulating some of the forces and impacts our bikes might be subject to, we’ve designed our own.

    We relentlessly cycle test for fatigue from pedaling and torsional forces on every single frame size, with deflection tests for stiffness at every point of the frame. Brutal impact tests with massive weights dropped on fixed frames or forks are performed. Then reversed, with weights attached to the frame, the frame hoisted to a given height depending upon product type, then released.

    This destructive testing is enormously instructive and important. And it is in continual process. But it’s our ongoing non-destructive testing of frames and forks fresh off the factory floor that’s just as vital.

    For our carbon fiber frames, 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. Each deflection test must fall within 5% of the standards our machine and field-testing have established. This weighing and stiffness deflection testing guarantees every single frame we produce meets all Jamis manufacturing protocol and will

    deliver the ride qualities we defined and demand.

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    SYNTHESIS IS SMALL BATCH

    The Icon is not just a lighter, faster version of our Venturas. When we put this project on the design board, we knew we didn’t just want to make a bike that could make a difference. We also wanted to MAKE it differently. Which is what Synthesis is all about: small batch manufacturing. A process that understands a great riding experience begins with a great building experience, one frame at a time.

    Frame Philosophy

    The ICON series frame was modeled after the Xenith Team. Think Xenith Team in butted aluminum instead of carbon fiber and you have the idea. We attempted to replicate EVERY attribute of the Team in the Icon and tested numerous protos on both our machines and the road repeatedly to get it right. From the precise and snappy handling in turns, to the out-of-saddle explosiveness in sprints, to the solid descent manners that inspire high-speed confidence. Combining the proven race-winning geometry of the Xenith with the durability and affordability of aluminum makes this an ideal CRIT bike, capable of delivering as much acceleration as you can provide the kick for.

    Weight

    Our goal was to build an aluminum racing frame that weighed no more raw than our Omniad T700 carbon fiber Xenith Pro and Race frames, also raw. That meant a target of 1150 grams for a 56cm frame. We’re proud to print (and we’re big on being accurate about our weight proclamations) that we’ve produced multiple 56cm prototypes and all have weighed within 0.1% of 1150 grams. So scrap the thought that you have to buy carbon fiber to get a bike that’s light enough to race. The beauty of the Icon frame is that it’s light, stiff, durable AND costs much less to manufacture than a carbon fiber frame. So the Icon parts package can be considerably up-spec’ed over a comparably priced carbon fiber bike, ensuring that the Icon will ALWAYS be lighter.


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    FOR THE LEADING EDGE

    Our chief design criteria when engineering the Xenith frame platform was to make it lighter, stiffer, more impact resistant, more comfortable and more aerodynamic. In that order.

    The professional riders of Team Jamis/Hagens-Berman p/b Sutter Home were adamant about what to do when told we were working on the next gen Xenith and wanted their feedback on every element of the frame they had been racing (and winning) on before our engineering team would commence. Their response was unanimous -- if you can make it stiffer for the sprinters great; if you can make it lighter for our hill climbers, great; as for impact resistance, comfort and aerodynamics, sure, if you want, but don’t change a thing about the fit, handling or the balance of the bike, it’s perfect as is.

    With the teams’ design guidelines defined, we did lighten and stiffen the new Xenith frameset and we did increase impact resistance and comfort by implementing NearNet SPV.

    But we also improved aerodynamics. The advantages of our original Windshield fork, which shrouds the rear-facing front brake on our T2 time trial bike within the fork blades, has been proven time after time in the wind tunnel and on the racecourse. That project and experience led us to develop a lighter version for use on the new Xenith SL, Team and Pro. Our new Windshield II fork design with trailing direct-mount brake reduces drag by nearly 4% compared to last year’s fork with leading caliper brake. An advantage you’re sure to appreciate the next time you’re pulling a breakaway or closing the gap solo.

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    EQUIPPED WITH ENDURO

    Last year, we made the switch to USA made Enduro Bearings in the bottom brackets on many of our high-performance level models. Why? Because they are the experts when it comes to obsessing about bearings! Enduro Bearings pioneered MAX type bearings, a design previously only used for large equipment such as forklifts and earth movers almost 20 years ago for bicycles to address the challenges associated with mountain bike pivots.

    By filling the races with balls, these bearings have 35-40% more load capacity than standard radial bearings. They accomplish this with a special design where the maximum number of balls are inserted into the bearing. The race grooves are deeper on these bearings for more lateral support for the twisting and multiple forces associated with mountain bike pivots. LLU seals give maximum protection against the elements while keeping the 90% fill of Almagard Extra High Pressure Grease inside. We also specify MAX BLACK OXIDE bearings in our carbon frames which get an additional Magnetite treatment for hardness, rust resistance and even more reliability

    In addition to these BB bearings, we’ve also gone ahead and made these bearings standard on our MP4 suspension bikes. The result for you is a much more active and quick rear suspension, eliminating play and wag all at the same time. Out of the box, our DEFCON & XCT suspension bikes with Enduro’s MAX bearings will save you time and money, as they will perform well 2 or 3 times longer than off the shelf bearings.


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    SIZE SPECIFIC DESIGN

    Size Specific Design (SSD) is the Jamis design philosophy and technique used to create the best possible riding bike for each size rider. Rather than limiting frame size variations to just different length top, seat and head tubes lengths, we take an all-inclusive look at each frame’s total configuration. We start by plotting stack and reach--the two most critical coordinates in bike fitting. Stack is the vertical line measurement from the BB center to the (real or imaginary) horizontal TT line. Reach is the horizontal line from head tube center to the vertical BB line. The two create an inverted “L” to then build outward from.

    With SSD we offer four different BB drops and three rear centers (or rear triangles) in addition to the natural variety in tube lengths as bikes move from size-to-size. This approach to frame making helps create an effective custom “ride” for each size bike. For example, consider that crank arm lengths vary as bikes get taller or shorter, yet without changing the BB drop to accommodate this, a rider sits higher or lower. This can have a very real affect on a bike’s ride characteristics and overall handling. The same rule applies to the rear center of the frame.

    Just the right amount of fork offset and trail round out SSD’s geometric equation. We have two different fork offsets for each model and with the tire versatility of the Renegades we have added a third to keep steering precise no matter the tire size choice.

    Our Size Specific Tubing (SST) that we pioneered back in 1988 also plays a key role in our new SSD technology. By building with a variety of frame size specific main tubes and seatstays, SST helps contribute to a highly optimized ride and assures the lightest possible weight in each case.


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    PLUS TIRES

    A 3” tire, when paired with a 26” or 27.5” rim size, results in an overall outside diameter of the standard version of the next larger mountain bike wheel size. In general, a 27.5 rim with standard 2.2”-2.3” tires results in an overall outside diameter of 27½ inches. 26 Plus is achieving this same overall outside diameter of 27½ inches by downsizing to a 26” rim but pairing it with a 3” tire. Same when looking at 27.5 Plus. A 27.5 rim paired with a 3” tire results in approximately a standard 29er outside diameter.

    Larger volume tires on wider rims allow for lower air pressures to be used , especially when set up tubeless, resulting in a larger contact patch with the terrain. Having more knobbies on the ground results in more traction and additionally provides the ability to float easier over rocks and roots. By outfitting our 27.5 and 29er trail hardtails with 3” tires, inexperienced riders benefit from the increased stability, float and traction. At the same time, more traction allows seasoned riders to ride terrain even faster and with greater confidence.


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    BOOST 148

    Boost 148 moves the rear hub flanges 3mm outboard on each side in order to improve the spoke bracing angle. The spoke bracing angle is the angle formed between the spoke and the vertical plane. By moving the hub flanges outwards, spoke angles increase, creating a more stable base. Larger spoke angles are able to balance a larger component of the lateral forces exerted in the horizontal plane during loading. So, with a wider hub shell comes better bracing angles of the spokes, which results in a stiffer, stronger wheel.

    With these minor shifts in flange spacing, the brake rotor mount and the freehub body location have to be taken into consideration and boost bikes compensate with adjustments to the chainring position. In order to get the best shifting performance, with the cassette 3mm outboard, the chainline (the line from the chainring to the center of the cassette) needs to be moved to accommodate that new position. It is necessary to move the chainrings outboard by 3mm and this shift can be accomplished with a redesigned crank arm spider. The crank arm Q factor (the distance between a rider’s feet when they’re on the pedals) and the frame’s bottom bracket shell width remain the same. With the chainline shift outwards, the frame is afforded more tire and chainring clearance and can maintain short chainstays.


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