THE EVOLUTION OF SPEED. INTRODUCING THE SMART ENVE SYSTEM.
The recipe for a fast wheel is no one single element; rather, it’s a combination of factors. When you start with in-frame development and blend proven aerodynamics, optimized stability, lightweight, stiffness and durability, the result is a revolutionary wheel design. Introducing the Smart ENVE System.
SPEED
The Smart ENVE System optimizes the interface between the frame surfaces and the wheels, creating an integrated system. The front and rear wheels interact differently with the air and the rest of the bicycle. Rim shapes are optimized to allow airflow to stay attached at higher yaw angles, thus reducing drag and improving ride performance.
The front wheel is wider and shallower to improve stability and reduce drag in any wind condition.
The rear wheel is deeper to reduce drag where stability is less affected.
Wheels were tested on multiple frame designs in order to produce the maximum drag reduction. The result is a wheel system, which handles predictably, and displays superior drag results when installed in multiple bicycle frame designs.
STABILITY
Steering feedback in variable conditions needs to be predictable to have total handling confidence. Less predictable wheels have a non-linear steering response, resulting in erratic and unpredictable handling in unsteady conditions. The shape of the Smart ENVE System rim is optimized to ensure even and predictable airflow attachment. What the rider experiences is a balanced build up of side force as the angle of crosswind changes. This allows the rider to accurately predict the handling mannerisms of the wheel and avoid dangerous over correction cycles.
The focus on steering stability resulted in improved handling and confidence in varying crosswinds.
Therefore, the wheel shape was optimized to produce a predictable and linear response.
The target stability gradient was 1.0.
STRONG, STIFF, LIGHT – THE ENVE PROCESS
ENVE is renowned for developing the strongest, stiffest and lightest rims on the market. This durability is proven across all disciplines of the sport including being the first and only carbon wheel to podium at World Cup DH events. All ENVE products, including the Smart ENVE System, share this advanced manufacturing technology. These technologies involve:
Highest strength to weight ratio in the industry.
Proprietary molded in spoke hole technology.
Textured braking surface allowing for a more positive engagement and better braking in wet conditions.
Aerodynamic Stability
We can all remember the first time we pushed the pedals of our bike with a newly upgraded high-end wheel set. It was a pure speed sensation in comparison to the wheel sets we had replaced. Going from a high-end “non-aero” wheel to a high-end aero wheel is an equally thrilling experience. The first time you ride an aero wheel in a road or TT bike is a special moment because you can’t believe how fast they feel. The performance improvement over a standard wheel is very significant.
Yet once someone has ridden a super-fast wheel set for five minutes, attention invariably turns to the stability of the bike through varying cross winds. To date, most aero wheels are sold on the basis of their axial drag performance.
Traditionally, a deeper wheel gives lower drag through increased side force, so there is more load on the side of the wheel, which the rider needs to counteract with steering force. At a certain wind angle the airflow will separate, and then the steering force has to be reduced making it difficult for the rider to maintain their desired line. Often the condition becomes unstable and takes several steering inputs to get the bike back on line, which can potentially be very dangerous in a TT or triathlon. This instability can cost valuable time when you need to come off the extensions to stabilize the bicycle.
As a result, before development began, the Smart ENVE team established an overall objective of developing wheels that optimized aerodynamics and stability. The team established a process to put a metric to the level of stability of the bike in a crosswind. Thus, the ENVE Stability Index (ESI) was born.
ENVE Stability Index (ESI)
This is by far the most important variable, and it has taken extensive research to define a wheel shape that is both fast and stable. All three wheel systems have a very similar level of stability, and are optimized for speed and ride-ability.
Traditionally, wheel testing in the wind tunnel is done in steady state; where the wheel is held for a period of time at a constant angle. In the real world wind gusts, gaps in the hedgerows and buildings will cause instantaneous changes in wind angle. The science of wheel stability has led us to look at transient aerodynamics or unsteady aerodynamics.
In fact, it’s only in recent years that Formula One has started to look at transient aerodynamics. Smart’s experience in F1 aerodynamics actually started when he was a trackside engineer and the racecar did not produce the down force that it did in the wind tunnel. This led to an extensive correlation study to understand the differences between steady state wind tunnel data and transient real world aerodynamics.
The team’s research in the wind tunnel showed that the wheels with poor stability had a non-linear steering torque response curve. So when the wind angle fluctuates by more than a few degrees at a given yaw angle, the variation in steering torque can be quite high. In certain cases its necessary to reduce the steering force (away from the wind) and this tends to make the rider feel unbalanced and often oscillate and lose the desired path of travel.?
The team’s key conclusions were:
Within reason riders could handle a build-up in side force on the wheels by shifting their weight around slightly on the seat and turning the wheel into the wind so that it felt stable.
Having some steering force build up was preferable to a totally neutral steering force in a crosswind. However, this needs to be limited so that the difference in steering torque is not too high in very gusty situation where the wind angle changes.
The biggest problem for all the testers was steering stability and the unpredictability that most of the test wheels demonstrated. To have total confidence, the wheel needed to be very predictable so that required changes in steering input were minimal.
From this, the team set out to establish the following performance metrics and objectives:
All wheels should ideally have a linear response to steering input vs. steering angle. In the real world this is very difficult to achieve so the metric was defined which related to the linearity of the curve. The Conventional wheel has an index of 0.27; ENVE/Smart aimed to get our products as close to 1 as possible.
THE ENVE PROCESS – STRONG, STIFF, LIGHT
In designing ENVE wheels, our engineers set out to produce the strongest, fastest, stiffest, lightest and most durable and reliable wheels on the planet. Through materials, tooling and finite processes, our engineers were able to design features into each wheel that addressed all the major historical issues carbon wheels have been renowned for: low spoke tension, spoke pull through, spoke breakage, low hoop strength and poor, uneven braking.
So what are the differences between an ENVE wheel and other carbon wheels?
Perhaps the major difference is that we have a patented process where we mold in the spoke holes. Carbon fiber gets its strength from running continuous, not broken fibers. Routing the fibers around the hole effectively increases the strength of the area around the spoke hole, thus allowing us to build a higher tensioned wheel. That's up to 130kg in the front and 150kg on the drive side rear. A stronger spoke hole also reduces the possibility of spoke pull through. A conical surface is molded into the inside of the rim to optimize the interface with the Pillar nipple. This allows the spoke to articulate as it exits the spoke hole, ensuring that it won't bind on the rim; greatly reducing the possibility of spoke breakage.
Since all tooling is machined in-house to extremely tight tolerances, ENVE's proprietary molding process can incorporate extreme pressure in the tooling. This creates a flat, round part straight out of the mold, and further, the raised braking surface is then machined to eliminate any irregularities. Our proprietary grey pads are recommended with our rims as our testing has proven that these achieve the best results in dissipating the heat generated when braking.
Finally, we don't have to "reinforce" any areas in the part to account for drilling. That, along with the high pressure molding, yields an incredibly light and strong rim - an altogether superior quality product that delivers everything you could possibly expect from a top of the line, pro level race wheel.
CARBON AND HEAT
A carbon rim is a marvel of structural engineering when you consider the dynamic loads due to spoke tension, tire pressure, road impact, and the weight of rider that the wheel carriers. Carbon fiber road rims must also be able to manage heat and braking forces throughout the lifecycle of the rim.
Obviously managing all these demands creates challenges. However with constant innovation and the use of the latest technology, combined with rigorous testing, these challenges can be overcome and the result is a wheel that inspires confidence and wins races.
At ENVE Composites, we build all our wheels in the U.S. in our own factory, right next to the engineers that design them. This allows for continuous incorporation of the latest materials and manufacturing techniques and an ability to bring the latest designs to market quickly.
When it comes to creating a rim that can handle break heat, ENVE not only uses the latest aerospace high temperature resin and fiber systems, but we also rigorously test each wheel design on a state-of-the art test fixture designed in conjunction with The Utah Center for Aeronautical Innovation and aided by a grant from the State of Utah.
The machine works by spinning a wheel using a chain and simulated rider load and then applying braking force while measuring temperature at multiple points hundreds of times a second using laser technology. The machine can also precisely measure wheel and tire width and see how these dimensions change as braking is applied and heat is generated.
ENVE has tested all our rims as well as the other carbon rims on the market to create baselines of acceptable performance. From there we have set an internal goal to be either the top wheel or in the top 10% for each wheel category tested. So for example, we test clinchers separately from tubulars and we also test each rim depth separately.
Over the last year improving the performance and longevity of braking on the 100% carbon-braking surface of our road rims has been a priority for ENVE. Part of this effort has been to develop a new brake pad compound that will optimally manage heat, minimize abrasion, modulate, and perform in wet conditions with our rims.
While machine testing is essential for research and development, nothing can replace real-world testing. Fortunately, ENVE Composites is located near the steep Wasatch Mountain range. Our local lunch rides include the North Ogden Pass (2.6 miles, 1500ft. descent), and Powder Mountain Road (8 miles, 3500ft. descent).
Using the brake testing protocol in conjunction with our ride-testing program we have determined that the ENVE Grey brake pads, which were developed as a result of our testing, manage brake heat and rim degradation in addition to having better modulation than the other pads and compounds that we have tested.
As with any new technology, we continue to make advancements with both materials and process to improve our wheels across many dimensions.
ABOUT SMART
Simon Smart, an ex Formula One aerodynamicist with fifteen years of engineering experience at the highest level of motor sport, earned global recognition for his design and development of the Giant Trinity and Scott Plasma 3 TT frames in the wind tunnel - both manufacturers realizing overnight success in the ProTour with wins in team and individual time trials. Smart’s business is based on the same site as the Mercedes GP - Petronas team headquarters and wind tunnel in Brackley, Northamptonshire in the United Kingdom.
Smart is renowned as one of the most successful time trial frame designers in the world with no less than six bikes in the top ten at the 2010 Tour de France individual time trial in Bordeaux alone. Smart also co-developed the Scott Foil aero road frame as ridden by the 2010 HTC-Columbia team, and his distinctive designs have influenced a number of time trial/triathlon bicycles on the market today.
ABOUT ENVE
ENVE Composites, located in Ogden, UT, designs and hand builds carbon wheel and component systems for mountain and road bikes. ENVE is a company made up of passionate cyclists and engineers who have created a unique brand based around simple, functional design and commitment to excellence. ENVE employees have innovated and designed some of the world’s most respected products in the bicycle industry.
Based in Utah, all ENVE wheels are designed, engineered and manufactured in America. ENVE is known for designing and making some of the strongest, lightest, most durable wheels on the market as validated by riders including UnitedHealthcare who put thousands of test miles on the wheels.
THE SMART/ENVE PARTNERSHIP AND DEVLEOPMENT PROGRAM
Between the carbon manufacturing expertise of ENVE and the aero capabilities of SMART, both companies realized that there was potential for synergy, and the partnership was born in January 2010. The forging of this partnership was shortly followed by an extensive and on-going development program, and the official announcement of the ENVE/Smart partnership at Eurobike in September 2010.
The team decided that the ultimate wheelset needed to possess the following characteristics:
Superior strength to weight ratio
Outstanding durability
Excellent aerodynamic stability for its intended application
Minimal drag when fitted to the bike
To gain a solid starting point, the team ran initial benchmark tests and CFD analysis of popular aero wheels with a complete bicycle and rider mannequin to best replicate “real world” conditions. Following these rounds of testing, the team defined a test protocol and developed the appropriate hardware that not only measures axial drag, but other important aerodynamic variables. This specific testing equipment is used exclusively by ENVE at the Drag2Zero facility at the Mercedes F1 wind tunnel and is “Patent Pending.”
In order to test rim geometry and shape more efficiently and accurately, the team pioneered a new rapid prototyping technique allowing for hundreds of rim iterations to be tunnel tested for real world performance variables in the time it would normally take to run just a few. Overall, the team spent 100+ hours at the wind tunnel, produced over 100 prototype wheel sets, ran 1000 test runs and reviewed 10,000 data points.
Buy ENVE 8.9 SES Rear Tubular 10sp Shimano DT Hub Rear Wheel online