Fresh Thoughts, Familiar Source

Fresh Thoughts, Familiar Source

Last night I went to an event at Sausalito’s Above Category in which Zipp Speed Weaponry presented a new wheel, called the 454. Well, not just a new wheel, but a new generation of wheel. It represents as big a departure from existing technology and know-how as Firecrest did when it was first introduced more than five years ago.

What makes this rim different is easily apparent to the eye. The sawtooth shape is another expression of Zipp’s pursuit of improved boundary-layer aerodynamics. Firecrest, and it’s rounded spoke bed was undertaken for two reasons, to make the wheel fast and to handle better. The handling piece was a matter of low-frequency vortex shedding. That’s the buffeting you feel when you ride a deep-section wheel in a crosswind. Those dimples that dot Zipp rims—they’re termed ABLC for Advanced Boundary Layer Control—create a microturbulence at the surface of the rim so that the wind attaches and stays attached until it releases more gently than it would were the surface smooth. This new sawtooth shape performs the same sort of function; in creating turbulence at the spoke bed, the passing airflow attaches better and releases better.

wh_454_nsw_cc_v1700f700sr_11s_pair

The shape came about from Zipp’s study of natural structures with similar functions. The structure they noted most earnestly were the tubercles at the end up humpback whale fins that allow a beast bigger than a school bus to turn like a Mini Cooper. This field of inquiry is termed biomimicry, and Zipp pursued a number of sources of inspiration. That these shapes are a recurring theme in nature should be some indication of the idea’s validity.

To give you some idea of Zipp’s dedication to this pursuit, they produced 36 different rim prototypes. There were more than 6000 hours of CPU time in CFD testing, a volume I’ve never encountered in the bike industry. Consider that often how CFD testing is doing is that an engineer will often set up a test at the end of the work day and then head home. If they’re lucky, that test will be complete when they return to work the next day. On average, that’s 12-ish hours of testing per day. Real world wind-tunnel testing was similarly gargantuan, with a whopping 252 hours spent in the wind tunnel.

wh_454_nsw_cc_v1_700sr_11s_detail2_hyperfoil

The sawtooth shape results in a rim that varies between 53 and 58mm of depth. The node, or bump that helps give the rim its sawtooth shape is called Hyperfoil; it’s this shape that increases the frequency of the vortex shedding so that in crosswinds a deep-section wheel can feel like a box rim.

The ABLC dimples have changed shape—yet again—and are now hexagonal, a development they are calling Hexfin.

wh_454_nsw_cc_v1_700sr_11s_detail_hexfin

For the record, I have not had the opportunity to ride the 454 wheels, yet. And I’m presenting their claims to you with some explanation but no jaundiced suspicion. Why? My experience with Zipp’s work has been that with each new generation of Zipp wheels they have met their claims. I’ve never melted one of their carbon clinchers, and they continue to be the best-braking carbon clincher on the market—Zipp even asserts that it’s Showstopper brake surface stops better than an aluminum rim, when paired with their Tangente brake pads; I can at least report satisfying braking. When it comes to deep-section carbon wheels in windy circumstances, especially gusty ones, only Enve rivals Zipp for the handling title. Without Enve as a competitor, Zipp would be peerless for carbon wheel performance.

These wheels are the most challenging to produce Zipp has ever offered. Each rim requires 12 hours of hand labor to produce, and all the rims are made, and wheels built, in Zipp’s facility in Speedway, Indiana.

454-comparison

Zipp uses Sapim CX-Ray spokes for their builds, 18 front and 24 rear. The front wheel weighs in at 690 grams front and 835g rear, for a total of 1525 for the wheelset. The rim has a 17mm internal width and a 27.8mm maximum outer width; it’s optimized for 25mm tires, and for the time being, this is a clincher-only wheel.

There’s a bottom line, performance-wise. The 454 is reported to be faster than Zipp’s 404 NSW wheels, while offering the handling of their 303 NSW wheels. It’s an intriguing assertion and one I’m eager to put to test.

Of course, all this engineering and technology comes at a price. For anyone whose frugal sensibilities are easily disturbed, just hit the back button now. For the rest of you, the take-home price is $4000 for a set, though front and rear wheels will be available individually.


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15 comments

  1. Craig P

    Amazing stuff. Not something I’m likely to buy, since I’m more an endurance bike rider, but I love seeing the technology pushed forward. And who knows – this tech may ” trickle down ” over time !!

  2. Miles Archer

    I am extremely unlikely to buy a $4k bike much less $4k wheels. Doesn’t matter, I still find this stuff fascinating.

  3. dAN

    I wish that Zipp would get behind Tubeless tires.
    I won’t buy a wheel-set that isn’t tubeless compatible.
    I likely wouldn’t ride these if given to me.

    1. Craig P

      Agreed Dan. I’m 100% sold on tubeless. I even converted my wife’s HED Jet 6 wheels and a Jet 9 wheel to tubeless for her Cannondale Slice tri bike ( I modified the carbon fairing to be to install tubeless valve stems ). Maybe someday these wheels will be tubeless, and only $ 1699.00. Add centerlock disc rotors and I’m all over it !

    2. Winky

      We’re different you and I, Dan. I prefer the convenience, light weight, excellent ride and reliability of tubes. No white goo to muck about with, no need to check that hasn’t gone hard, no need to clean it off my bike (or the rider behind) when I get a cut sidewall, no hard to mount tires, no need for compressors or weird accumulator pump systems to seat the beads, no burping air, and compatible with CO2. What’s not to love about tubes?


    3. Author
      Padraig

      Thanks for sharing that. I’ve had conversations with them about tubeless and it’s on their radar big time. However, aerodynamics are their bigger concern—at least for these wheels. I’m hopeful that at some point their designs intersect with tubeless. I know people who have set up tubeless tires on their rims with success, but it’s not something they recommend; I wouldn’t recommend it either.

      These wheels do force an interesting question: will you give up the tubeless advantage to gain speed and improved handling? For me, that answer depends on what bike and where I’m riding. I can’t say I’d answer the same way for every condition.

  4. Dan

    I totally hear you.
    I think the work is probably the same in the long run with both tubes and tubeless. I use tubeless to decrease the amount of flats I get as I ride my road bike on dirt roads a ton as I live in Vermont and have to. When I do get a flat it is a huge pain in the ass but much less frequent.

  5. Steve

    I’m all for advancing wheel technology, however Zipp doesn’t exactly have the best record on the consumer side. Soft builds, poor QC combined with too many different iterations of hubs that have a loooooong history of unreliability, recalls, and even injury. Cool rim, though not nearly enough to pull me away from Enve. It takes a great build with reliable parts to justify the upgrade, something Zipp always lacked during their entire history dating well back before the SRAM merger. In almost 20 years on carbon wheels Zipp has always been my least favorite.

    1. STS

      I second that, Steve. Especially Zipp hubs have always been sub-par at best. And if a company continues year after year to sell their wheels with problematic hubs despite all the problems customers have with them what does that tell you about their preferences?
      For me it’s a strange business decision to invest so much time (engineering resources) and money into a most probably minor aerodynamic refinement of your wheels line-up when most of your customers are looking for an improvement of the hubs and tubeless tire compatibility to give them more peace of mind with regards to the danger of melting tubes.
      But maybe their mechanical engineers responsible for the hubs simply don’t have the same calibre as their aerodynamic specialists and their marketing guys. The latter are definitely leading the bunch only second to Oakley’s maybe ;-).
      I’m curious to learn whether those wheels will succeed in the market. 4k $ for a wheelset looking very … ahem different will most probably not help. Or maybe it will even heat up the demand.

  6. Pingback: Change the World with Bikes, Win Mind-Blowing Prizes: the 2016 WBR Grand Slam | RKP

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