Zipp 858 Carbon Clincher – First Look

Some things are going to be surprises at Kona. But Zipp finally making the Zipp 858 official wasn’t going to be one of them. We have been seeing the 858 for a while now – most noticeably at the Tour de France this summer. But until now we have been speculating on when it would be official (and what exactly would it be called – 858 or 898). Well the answer to that is “today” and “858”.

We first saw the shape of the 858 just about 11 months ago when Zipp introduced the 454. The shape comes from biomimicry. The imitation of the models, systems, and elements of nature for the purpose of solving complex human problems. Previously, this technique had been utilized in aviation, motorsports, energy production, and other industries. Zipp decided that cycling was where it belonged next. We rode the 454s this spring and said “if you have the budget and are looking for stability and speed, the 454 NSW should definitely be on your short list.”

The 454 was defined by the shape that Zipp calls Sawtooth. SawTooth is the name given to Zipp NSW’s patented variable depth 454 and 858 rims. The legendary Zipp dimples are updated with the 858 called HexFin ABLC. These dimples are the hexagonally shaped depressions found at each individual node of our Sawtooth shaped NSW rims. The angular shape of each dimple increases boundary layer mixing to help keep airflow attached to the rim for reduced aerodynamic drag and improved stability in crosswinds. To further improve the effectiveness of the hexagonal dimples, they are arranged in fin-shaped clusters made up of variable sized dimples that work in concert with each node of a Sawtooth rim.

The 858 is meant to take that stability of the 454 and go deeper. In Zipp’s words – “Faster than an 808. Rides Like a 404.” Those are some serious words – but based on our experience with the 454 as well as the 808 NSW we suspect there may be something to them.

The 858s also get Axial Clutch technology. Every time a conventional hubset starts to coast, friction within the freehub ratchet mechanism works like a drum brake to slow the rider down. With Axial Clutch, the ratchet mechanism is disengaged when coasting. It then uses magnets to re-engaged once the rider starts pedaling. The goal is to allow you to hold your speed longer as you hit the turnaround point.

Rim brake models (there are both rim and disc options of the 858) get Zipp’s Showstopper brake track. Showstopper adds directional, molded-in, texture paired with silicon carbide (SiC) particles suspended in the surface resin. SiC is nearly three-times harder than hardened steel, which helps ensure a strong and consistent braking experience. The grooves on the wheel also help to wipe water away and act as cooling vanes.

Rim brake versions have a max width of 24.4 mm in the front and 23.7 mm in the rear with a variable depth from 77mm to 82mm. They weigh in at 1,750 grams. Disc brake versions have a max width of 23.7mm front and rear and the same variable depth from 77mm to 82mm. They weigh in at 1,834 grams. Both options will set you back a cool $4,400.

We reached out to Zipp in regards to the downsizing of width. From Daniel Slusser at Zipp:

The reason behind the 858’s width was to reduce aerodynamic drag. In the absence of a crosswind, a narrower wheel is always aerodynamically faster. One of the reasons aero rims have grown wider (an innovation first made by Zipp with our Firecrest wheels) is because with a conventional rim, wider rims are less affected by crosswinds. With the Sawtooth rim design we’ve improved crosswind performance so much that we were able to go to a narrower rim and improve the aerodynamics even more. In short, we are able to get the best of both worlds—a wheel that is aerodynamically faster and more stable in a crosswind than a wide conventional rim.

We are looking forward to spending some time with these wheels. We loved the 454s, and expect the 858s to be every bit as stable to ride with a bit of extra speed to boost. We know these are a set of wheels not for everyone – but we expect these will start showing up pretty quickly in transition at major races next year. And we know that we can expect to see these wheels out under a few of the leaders of this weekend’s race. You can be sure to see a set at AeroGeeks HQ in the coming months as well. And make sure to continue staying tuned to for your latest Kona coverage.

[Updated on 10/11 with a quote from Zipp]

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