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Autor: ferlin | Publicado: 2012-11-15T08:53:00-08:00


        
            EXCLUSIVE: DVO Emerald Inverted DH Fork - First Look                    


                        Nov 13, 2012 
                        

    

        
        
        
            
                       

    


        
            
        

          
        


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It
 has been a quick seven months since DVO, short for Developed 
Suspension, was formed after Bryson Martin and engineer Josh Baltaxe 
departed from Marzocchi. Bryson, who has been in the suspension game for
 23 years, quickly began outlining a plan to offer something different 
than what consumers may be used to, not just from a product standpoint, 
but from a company approach that contrasts with what many have come to 
expect. ''I really wanted to do it right, so we needed everything all under one roof and that’s what we have accomplished,'' declares Martin. ''Now
 that all the ideas, designing, and engineering all happen in one place,
 it’s a lot easier to set goals and execute on them.'' It wasn't 
long before both Tom Rogers (product development) and Ronnie Dilan (head
 technician) left Marzocchi to join Martin and Baltaxe and plans were 
laid for DVO's debut fork. Whereas the current major suspension players 
all offer a massive range of products to choose from, DVO plans on 
producing a limited selection of high-end products, beginning with the 
203mm travel, inverted Emerald shown here on Pinkbike for the first 
time.


We
 know the benefits to an upside down fork and it's been a very long time
 since a company brought an inverted fork to market. We wanted to make a
 statement by executing it when other companies couldn't.- Bryson Martin, DVO


While
 this is the very first complete Emerald to be assembled, each of the 
fork's different elements have been tested in some way during 
development. The Emerald's open bath twin tube damper system, for 
example, was surely put through real world testing while hidden within 
another fork maker's chassis, likely making its way down trails and past
 other riders without anyone taking notice. Martin is understandably coy
 about what fork the damper was trialled in, but he did reveal that 
early versions of the Emerald were coil sprung prior to the air spring 
system being developed. The fork shown here, as well the production 
model, will make use of an air spring, and DVO is also looking at 
including an adjustable volume feature that will allow riders to tailor 
the fork's ramp-up through its stroke. Interestingly, it will employ a 
coil negative spring that will have an adjustable preload component to 
let Emerald owners adjust the fork's initial stroke.

 
               
         

Emerald Details 

Intended use: DH/FR 
Design: Inverted 
Travel: 203mm/8''
Stanchions: 36mm w/ molybdenum disulphide coating

Upper tubes: 43 - 41mm tapered 7000 series aluminum 
Steerer tube: 1 1/8th straight or tapered options 
CTA: One-piece Carbon Torsion Arch acts as stanchion guard/fender while increasing torsional rigidity by a claimed 50%
Fork crowns: Forged and CNC machined. Separate crowns for 26'' and 650B-sized wheels to preserve trail geometry, direct mount stem compatible
Spring: Air 
Damper: Twin-tube open bath design 
External damper adjustments: Separate low and high-speed compression/rebound 
Negative spring: Coil w/ adjustable preload 
Target weight: 2,900 - 3,000 grams/6.4 - 6.6lb 
Availability: June/July of 2013 
MSRP: To be announced 




Inverted DesignThe
 DVO team knew they wanted to pursue an inverted layout for the Emerald 
due to the design's lighter un-sprung weight, consistent lubrication 
qualities, and ease of compatibility with non-26'' wheel sizes. And 
while those points are certainly all valid, there is a reason the large 
majority of suspension forks on the market employ a traditional 
right-side-up layout: torsional rigidity, or rather the inherent lack of
 it in an inverted design. Inverted forks are ubiquitous in the 
motorized off-road world, as proponents of the design are quick to point
 out, although it could just as easily be argued that weight is much 
less of a concern on a dirt bike, therefore allowing for massive tube 
diameters, thicker tube walls, and burly crown and axle clamps, all 
features that make for a much stiffer (and heavier) fork. But even when 
similar methods are applied to the front end of a mountain bike, the 
result can't approach the outright stiffer design of a right-side-up 
fork. Is that necessarily a bad thing, though? ''Compliance on a mountain bike can be a great advantage but it must be in the right locations,'' says DVO's Bryson Martin. ''As
 more DH and Enduro frames are made from carbon where stiffness is 
generally accepted, the suspension must become more compliant - 
structurally and hydraulically - to optimize the entire bike.'' 


We feel that the industry puts too much emphasis on stiffness in general. Stiffer doesn't always mean better.- Bryson Martin, DVO


The
 general consensus for most mountain bikers, though, is that one's 
front-end can never be too torsionally rigid - it is a mantra that has 
been drilled home thanks in large part to manufacturers claiming massive
 gains in stiffness with every new product. But is stiffer actually 
better? There is certainly a point where too much torsional flex will 
begin to have a very negative effect on performance, making for vague 
and unsettling handling but, as Martin alludes to, just the right amount
 of torsional compliance can also allow the front wheel to track more 
smoothly on rough ground, something that designers at the top flight of 
MotoGP, among other sports, have known about for many years. It is a 
little known fact that, during testing, one downhilling’s most 
successful racers actually cut the arch off of his right-side-up fork in
 a search for more torsional compliance! So, if a given amount of 
torsional compliance can be an advantage, the question remains: how to 
tune-in the desired amount without creating an overweight fork? DVO's 
answer lies in their proprietary Carbon Torsion Arch, or CTA for short.



Carbon Torsion ArchLikely
 the biggest talking point of the Emerald will no doubt be the carbon 
fiber, bolt-on CTA unit that serves to not only protect the stanchions 
from damage and as a fender, but also to tie the lower legs together to 
increase torsional rigidity by a claimed 50% over the same Emerald fork 
without the CTA in place. The basic idea isn't new - riders who have 
been in the sport since the mid-90s will likely recall the inverted, 
elastomer-sprung and air-damped Halson fork that had its lowers joined 
together via a brace that traveled vertically by way of slots machined 
into the fork's uppers. The CTA's execution looks to be much more 
impressive, but we'll need some trail-time on the Emerald to see just 
how effective it actually is.
The
 unit features a unique core (Martin was reluctant to share certain 
details at this point in time) within its otherwise full carbon fiber 
construction, with the design said to resist torsional loads while still
 being light, strong, and durable. DVO isn't simply trying to add as 
much rigidity as possible by incorporating the CTA unit, though, with 
Martin stating that ''This design will still offer some pliability, 
especially useful in rough, straight line sections, while providing 
stiffness in corners.'' A number of different CTA elements are in 
testing that use varying carbon layups with an eye toward a final design
 that offers the  rigidity and balance DVO is looking for. The idea for 
the bolt-on carbon element came about well into the fork's development; 
DVO was investigating how axle size and shape factored in long before 
the Carbon Torsion Arch was added to the Emerald's spec sheet. 
Interestingly, the idea of a hex-shaped axle (much liked those utilized 
on Manitou forks) was nixed when DVO found that increasing the overall 
clamping surface area of the axle proved to be a more efficient way to 
control slipping and flex. No, you won't find some oddball-sized axle 
utilized on the Emerald, but rather a very stout looking 20mm setup.



Being
 competitive in weight is definitely high on the list, but performance, 
reliability, and strength was more important for us, especially for the 
kind of abuse a suspension fork endures. 2,900 - 3000 grams is our 
target and we hope we are close but, more importantly, we want people to
 be stoked on the performance, adjustability, and durability of the 
fork.- Bryson Martin, DVO


There
 is no denying that the Carbon Torsion Arch concept is a clever way to 
go about increasing torsional rigidity without adding too much weight - 
DVO claims that it should only add about 200 grams to the package - but 
the question remains as to why such a design hasn't yet been put to use 
in the motocross or enduro realms. If the CTA unit is as effective as 
DVO asserts we may see it pop up in other places as well, including an 
inverted single crown fork further down the road, although that could be
 a ways out at this point. “We always want to look at each project individually and design a product that is optimized for its specific use.'' Martin continues, ''It
 follows our plan to stay focused and not just throw gizmos and features
 into a product that ultimately drives up cost and over complicates 
things for the end user.'' 


&nbsp;&nbsp;The
 Emerald uses a traditional 20mm thru-axle that requires tools to 
remove. You won't find any funky quick release axles or strange locking 
methods here.


Twin Tube DamperThe
 two most common damper layouts currently being employed within forks 
are either a sealed cartridge layout (FOX with their FIT cartridges, and
 RockShox, who turn the stanchion tube into the cartridge body) or an 
open bath cartridge (ala Marzocchi), with advantages and disadvantages 
to both designs when it comes to performance and weight. The Emerald 
doesn't make use of either one, though, instead employing an open bath 
twin tube layout that DVO feels is much better suited to long travel 
applications. ''A pure open bath system can have issues with aeration
 and cavitation, as well as having too much oil that adds unnecessary 
weight,'' Martin says. ''Twin tubes solve those issues, keeping damping consistent and oil volume to a minimum.''
 And while damper design is a topic that often results in endless 
arguments as to what actually does function best, the twin tube system 
is is found within some of the most acclaimed off-road moto suspension 
designs, especially those created by a certain highly rated Swedish 
company. A moto-inspired philosophy is one that rings true through much 
of DVO's thinking.


&nbsp;&nbsp;The
 fork's base valve and rebound assembly, complete with mid-valve (left).
 Tom Rogers shows off the fully assembled twin tube damper body (right).


While
 DVO is adamant that the open design of their twin tube damper makes the
 most sense for a pure DH fork, we might see something entirely 
different utilized within any shorter travel forks they may or may not 
produce down the road. According to Bryson, “ There is more of an 
advantage to running a closed system on a fork with less than 160mm of 
travel compared to using the same system on a fork with 203mm of 
travel.." This train of thought is in contrast to some other 
suspension companies who employ the same basic damper philosophy 
throughout their high-end fork lineup, be it a cross-country or longer 
stroke downhill offering.


When
 it comes to damping, it isn't about reinventing what has been proven in
 other areas, but about delivering value and performance to the end 
user, without the gizmos and hard to service designs.- Bryson Martin, DVO


The
 twin tube, open bath damper is exactly as its name would have you 
believe, with a secondary tube that sits within the fork. The damper 
piston travels up and down within this tube, but as opposed to it being 
sealed, oil ports on the wall of the tube allow damping oil to circulate
 between the inner and outer tubes, and through the valving. This layout
 should result in less cavitation (the formation of bubbles and foaming 
of oil under hard use), making for more consistent damping, and an 
optimized oil level that also acts as lubrication to keep the fork 
cycling smoothy through its stroke. Enclosed in the damper body is DVO's
 'Emerald Valve', otherwise known as the piston. DVO has gone to great 
lengths to create a piston that permits a lot of oil flow via smooth, 
open porting. This lets them control the fork's damping characteristics 
with more shims than would otherwise be required of a lower-flow piston,
 the advantage of this being a large degree of tuning by way of using 
more and different shims. The fork also uses shimmed rebound damping as 
opposed to a ported system, which is what some other suspension 
companies employ. Ported damping refers to oil flow through small holes,
 known as ports. One potential issue with ported damping is that at 
times oil simply cannot flow fast enough through the ports when 
required, resulting in very inconsistent damping. Shimmed rebound, on 
the other hand, allows for the same dynamic damping (the shims flex more
 or less depending on the forces involved) as found on the high-speed 
compression side of the piston. 


&nbsp;&nbsp;The
 Emerald's adjustment dials are sturdy aluminum units that are clearly 
labeled. Separate low and high-speed rebound is adjusted atop the right 
leg, while separate low and high-speed compression can be tuned via two 
dials at the opposite end.


User Tuneable DamperThe
 moto-inspired approach continues with DVO's decision to not only allow 
Emerald owners access to the entire damper assembly, but actually 
encouraging them to try their hand at tuning it. This is the exact 
opposite strategy that most suspension companies within the mountain 
bike world have taken throughout the sport's history (Manitou is an 
exception, though, with their Absolute Plus Tuning kit), with many 
riders being downright scared of opening up their fork or shock as a 
result. Yes, a certain amount of knowledge and skill are required, not 
to mention the correct tools for the job, but it is far from being 
rocket science. DVO will offer not only tuning kits, complete with shim 
layout suggestions and the expected results, but also on-line videos 
that will guide owners through the process. Taking it a step further, 
they also plan to hold in-house tech seminars for those who really want 
to jump into the deep end of tuning.








Since
 we rely heavily on piston and shim stacks to handle our damping, we 
have designed our pistons to be easily accessed so individual shim stack
 tuning can happen. Once the rider becomes comfortable with working on 
the suspension, it is very interesting to test different settings 
tailored to specific riding areas and skill level. We are committed to 
teaching riders all about suspension and we will provide a lot of 
information on how to tune our products so you can become your own 
suspension tuning guru!- Bryson Martin, DVO


Further
 helping matters is the Emerald's 'bottom loader' base valve that should
 allow owners to make changes to the damper without having to perform a 
full rebuild. Simply flip the fork (or bike) upside down, unscrew the 
compression base valve from the bottom of the fork leg, and pull it out.
 Minimal, if any, oil loss should occur. All dials are contained on the 
assembly, meaning that you won't have to fiddle with near-microscopic 
set screws or any tiny indexing ball bearings or springs. We've long 
said that most mountain bike suspension companies seem to go out of 
their way to make damper service and tuning a huge hassle, and it is a 
breath of fresh air to hear DVO's approach - garage tinkerers rejoice.


Titanium Collet ClampsAll
 current double crown forks in the MTB and the MX world utilize some 
sort of pinch-bolt system to hold the upper tubes in place, but DVO is 
considering a different method: collets. The collet system used on the 
Emerald consists of tube sections with vertical splines and an external 
wedge shape. Tightening a threaded ring (with the required spanner 
wrench) that is positioned above pulls the section upwards, locking the 
fork tube in place due to the wedge-shaped internal profile of the 
section. It is very similar to what is used to hold tool bits securely 
into high rpm machines (drills and CNC machines for example), although 
this would be the first time that a collet setup has been put to use to 
hold fork tubes in place. One upside of the collet design is the large 
and even clamping force it provides, but the system could also result in
 a lighter overall package compared to the more common pinch bolt 
arrangement. While all of the above sounds good on paper, and the design
 should present no technical issues due to the robust upper tubes of the
 Emerald fork, production costs may keep the collet clamping system from
 reaching production. If so, a standard pinch bolt design will likely be
 used on 2014 model year forks, with DVO hoping to put the collet system
 to use on 2015 products.26'' and 650B-specific CrownsWhile
 we're seeing 650B wheels infiltrate the mid-travel full suspension 
market at an alarming rate, the 26'' wheel is still firmly entrenched 
within the longer-travel downhill scene. That very well could change in 
the near future, though, and DVO plans to be ready for the shift. The 
Emerald's inverted design lends itself to being compatible across a 
number of wheel sizes by way of different fork crowns, with each setup 
optimized to preserve the same trail geometry, and therefore handling, 
across the board. Trail refers to the measurement aft of the steering 
axis that is created by the fork offset, head angle, and wheel size - a 
larger trail figure can improve high-speed stability, while less trail 
can create a more nimble handling bike. Messing with trail figures can 
have very adverse effects on how a bike handles, so it is vital 

that
 the number remains largely unchanged, a trick that employing 
differently offset fork crowns on an inverted chassis can accomplish. 
The 650B fork crowns will be slightly taller to handle the larger 
diameter wheel, as will the Carbon Torsion Arch unit. DVO is undecided 
as to if they will offer 650B conversion crowns and the CTA as an 
aftermarket item for the Emerald, but we're betting that we'll see them 
at some point in the future as the 'tweener wheels make their way onto 
true downhill race bikes. There is no word as to if DVO will offer a set
 of crowns and CTA that would allow 29'' wheels to be fitted, although 
if that did happen we would also expect the fork's travel to be docked 
slightly.



&nbsp;&nbsp;Head
 engineer Josh Baltaxe, along with Bryson Martin Jr., begin assembling 
the very first Emerald fork at Suntour's headquarters. Having the 
Taiwanese company's manufacturing and testing clout behind them should 
allow DVO to evolve relatively quickly.





&nbsp;&nbsp;The
 DVO team, from left: Bryson Martin Sr. - president and founder, Josh 
Baltaxe - mechanical engineer, carbon and structural specialist, Tom 
Rogers - product development.





&nbsp;&nbsp;Ronnie Dilan - head technician, JP - general manager, Bryson Martin Jr. - testing,


Shots FiredWhile
 DVO is just now assembling their first complete Emerald forks, and 
production units aren't slated for release until Summer of 2013, we feel
 that there is a lot to look forward to from the newly formed company. 
Bryson Martin and his team are responsible for much of Marzocchi's most 
successful products, but moved on as the landscape of the Italian 
company began to shift. ''We spent decades at Marzocchi, and they were a major player for a long time,'' says Martin of the Italian company's glory days. ''Things
 started going sideways with Marzocchi many years ago, though. These 
were issues outside of our control and we just held in there until we 
couldn’t anymore.'' It is still very early days, but Martin's 
separation from Marzocchi may have spawned a new suspension authority, 
one that aims to respond to what many consumers have been requesting for
 years: reliable suspension that is not only easy to work on and 
understand, but that also looks to mimic much of the principles found in
 the moto domain. And yes, it will be available in colours other than 
green.


Carbon
 fiber upper tubes and crown? The clamps are currently not a one piece 
unit, but we are working on it for a future version. A one piece carbon 
assembly involves a lot of testing, and it is something that we don't 
want to rush into.- Bryson Martin, DVO


Only
 time will tell if DVO's approach to high-end suspension will culminate 
in a winning product, but they certainly look to be on the right track. 
The Emerald may still be in the early stages of its evolution, but 
Martin is already talking up a version of the fork that will use a one 
piece carbon fiber upper assembly, not to mention the possibility of an 
inverted single crown fork added to the lineup. A rear shock is also 
being developed concurrently with the Emerald fork, and there is no 
doubt that it will carry the same moto-inspired DNA. No, DVO may not be 
looking to take a share of the large entry and mid-level suspension 
market, but it's fair to say that the reigning suspension powers are 
likely looking over their shoulder when it comes to their high-end 
offerings. We'd by lying if we said we aren't looking forward to seeing 
them rock the boat. Exciting times ahead. www.dvosuspension.com