Following on from the release of the new 353 NSW wheels earlier this year, ZIPP have been re-examining their 4-Series ranges and, despite a new model 454 last season, have re-released both the 454 NSW and 404 Firecrest.
Here’s the why.
In recent years, the concentration of development in bikes and wheels has been heavily weighted towards aerodynamics. Aerodynamics are undeniably a key element in making objects faster through the air and this recent focus was a function of the relative plateau in weight reduction and previous workings around what had become the norm in tyre width - 23mm.
With the adoption of discs and Tubeless technology, the scope for re-developing all key aspects of a wheel are once again opened up. Indeed, carrying on with a bias towards aerodynamics my even be a hindrance if you are trying to stay ahead. Zipp’s new approach to speed is not ‘just’ about aerodynamics. Rather there’s is what they term TSE : Total System Efficiency. It is obviously of so much benefit that they have re-engineered a wheel set that they released only a season ago.
In a nut shell, TSE is the optimisation of wheel sets from 4 key view points. Aerodynamics (Wind Resistance), Rolling Resistance, Weight (Gravity) and Vibration (Comfort).
Like bike fit, if you set up your road bike to put you in a position to be aerodynamically efficient, it is highly likely that you will become inefficient while climbing not to mention bloody uncomfortable over longer distance. Finding the optimal position on a bike is a process of identifying your goals and then tailoring your fit to find the best bio-mechanical position that is also sustainable for the riding that you are doing.
Performance focussed compromise and optimisation.
The analogy can be carried into the new 404 Firecrest, 454 NSW and 858 wheels (as well as the 353). The range of wheels can be viewed as the goal : 353 NSW as your climbing / lightweight aero wheel, 404 / 454 for All-round riding and 858 as your TT/Triathlon. With the goal (depth) established, you can then optimise the rest of the package to deliver maximal advantage.
For the new 404 and 454 wheels, Zipp have analysed last year’s rim profiles and using a combination of new laminate and a wider profile have enhanced the tyre interface. This change facilitates not only a reduction in aerodynamic drag but also assists in weight reduction, rolling resistance and vibration losses.
Hookless beads - that is Tubeless Specific rims rather than traditional hooked or clincher rims that are Tubeless Ready - have a huge part to play in this arena. It is the future. Hookless beads are just as safe as clinchers but offer some serious benefits. They make a rim lighter (both the 404 and 454 are around 350g lighter than their previous iterations - that's a jar of Nutella for those that work in chocolate spreads), stronger and more aerodynamic but they also use less material and are easier to form which delivers the dual bonus of being both more affordable and more environmentally friendly.
The most significant benefit of a Hookless, tubeless wheel is the rolling resistance. So much so that while Zipp have increased the rim width and profiles of their new wheels, this is more for the rolling benefit than the aerodynamic one. Indeed, last year's Zipp 454 NSWs are actually aerodynamically more efficient and save 3.6W over the new version and the new 404 Firecrest is less efficient by nearly 1 Watt.
BUT - what they lose in aerodynamics is more than compensated for by the rolling benefit.
A wider rim and wider tyre results in a wider and shorter tyre contact patch. This is critical as it promotes less tyre sag which deforms the tyre less and results in less energy lost in the rolling tyre.
The 404 claws back over 4 Watts in power when partnered with an optimal 25mm tyre run at the correct pressures. That’s nothing compared to the 454 NSW though. The new shape, combined with the optimal tubeless set up doesn’t claw back anything, it grabs a greedy handful and saves the rider a massive 13.9W over the previous version released just last year.
There’s more to the story though and this element is very often overlooked by consumers. Comfort. I’ve long been an advocate of comfort’s correlation with going faster - certainly for longer. The tubeless revolution is a double edged sword - many buy a tubeless set up without due consideration and simply run the set-up at the same pressures as their outgoing clincher system, completely negating the benefits of tubeless!
Tubeless tyres set ups are optimal at far lower tyre pressures than those of a traditional clincher. Check out the tyre pressure stable below. This not only benefits riders in terms of efficiency but also makes for a far more comfortable ride which is a win win. Whole body vibration (and therefore comfort and control) comes from the ability of the tyres to absorb the bumps in the surface.More pressure leads to more vertical movement - more bouncing around and the necessity for the rider to counter that - sucking up valuable energy. Lower pressures dramatically cut road input allowing you to be more relaxed, in control, comfortable and efficient - and that’s what makes you faster!
Alongside all the rim developments, Zipp have also refined their Cognition Hubs. Axial Clutch tech is a clever system that employs magnets to disengage the frehub slightly during freewheeling. This removes an amount of drag when no pedal forces are delivered. The new Axial Clutch V2 builds on this system by simplifying and enhancing it to further improve the benefits.
The V2 does away with the 12 internal components in favour of a single element that serves the same purpose and employs a material called SYLOMER widely used to create spring or damper assemblies in the automotive and medical industries. Combined with 54 rather than the previous 36 points of engagement, the new V2 Axial Clutch is not only 10g lighter but also reduces coasting friction by 23% at 40kph (25mph). So, the new 2022 Zipp wheels are not only faster when you pedal, they’re faster when you don’t!
Ultimately, the new 2022 Zipp Wheels deliver serious speed advantages to all riders a range of conditions while simultaneously delivering the comfort to keep you fresh and in control even on longer rides over questionable surfaces. All in more cost effective packages.
Optimised for 25mm tyres, the 404 Firecrest and 454 NSW also perform exceptionally with 28mm depending on rider weight where the rolling benefits outweigh the aero. Check out the Tyre Pressure Guide for your ideal set up.
Aside from the key revisions to width, the switch to a hookless bead and the improved hub mechanics, the 454 Firecrest retains its distinctive wind cheating biomimetic Saw-Tooth shape:
Developed using the science of Biomimicry Zipp were able to understand how for example a Whale is able to make rapid movements through special features on the leading edge of their Pectoral fins and how sharks are able to move effortlessly through the water thanks to structures on their skin - evolutionary fluid dynamics if you like. Ultimately Zipp have engineered similar features into their new wheel shape and surface features in order to further reduce aerodynamic drag and side force.
The 454 NSW's most obvious feature is its shape - Zipp call this Sawtooth and it is the most important functional aspect of the wheels. The biomimetic Sawtooth shape gives rise to a rim with varying depth from 53mm to 58mm this novel shape gives a reduction in both aerodynamic drag and a simultaneous reduction in side forces. Each rim section or node that transitions from 58 to 53mm is referred to by Zipp as a Hyperfoil and in conjunction with Zipps new evolution of their ABLC dimples - HexFin is responsible for reducing the size and therefore power of vortices leaving the rim. The hexagonal shape variable size and fin-shaped arrangement of the HexFin dimples reduces (to a greater degree than circular dimples) the boundary layer mixing of air across the surface allowing the wheel to move through the air with greater efficiency.
Ultimately the Hyperfoil shape dramatically improves the stability of the rim particularly at greater yaw (off-centre) angles giving the wheels the reactivity and handling characteristics of a much shallower rim (between 30 and 35mm) this saves the rider energy by reducung the effort to control the wheels in gusty conditions. The variable sized HexFin ABLC dimples further enhance this control while literally helping the rims slice through the air. Fast and stable.