The all-new Zipp 353 NSW is, says the US brand, its “most advanced wheel in every performance area” and is the first SRAM AXS-connected wheel, allowing real-time tyre pressure monitoring via the Zipp AXS Wheel Sensor integrated into its rim. For monitoring while riding, the Wheel Sensor pairs with a head unit via Bluetooth, with the tracking data written afterwards to the .fit file. Two LEDs allow a quick check before riding: green means it’s within the rider’s chosen pressure range and is good to go.
The rim itself has a new 35/40mm undulating shape that not only outperforms the previous 353 NSW in the wind tunnel across the yaw sweep, but with a new carbon layup Zipp says it has a 16% higher impact strength – and the weight is still a claimed 1,310 grams with the wide 25mm hookless rim bed retained.
There’s also a new ZR1 SL hubset, which is based on the robust ZR1 hub that’s been on the market for five years. The new version uses the same driver body mechanism with 66 points of engagement, but the bearings have been significantly upgraded to Zipp’s superior ceramic and they supply a weight reduction of around 30 grams. The 353 NSW will be priced from £3,500/$4,300 per set.
Zipp has also redesigned the 303, dropping ‘Firecrest’ and renaming it ‘303 SW’. Currently this is the only other Zipp wheel that integrates the AXS wheel sensor into its rim. Like the 353 NSW, the 303 SW has also received an upgrade: a revised carbon layup and design gives it an almost 10% improvement in impact strength for a relatively low weight of 1,440 grams, according to Zipp. The 303 SW is optimised for 30-35mm tyres and the rim features a refined shape that is designed to shield the tyre in an impact that would otherwise cause a pinch flat. The hub is the ZR1, which has stainless steel bearings rather than ceramic. “The 303 SW is a modern classic wheelset, fully capable of road, gravel, cobbles, and cyclocross riding,” says the brand. Pricing is from £1,700/$2,200 per set.
Other Zipp road wheels in the range have received less substantial upgrades: the 454 NSW and 858 NSW also get the new ZR1 SL hub, but the rims are unchanged and the AXS Wheel Sensor is not included.
But do we need real-time tyre pressure monitoring? Zipp’s Total System Efficiency (TSE) philosophy is about understanding and addressing every factor that contributes to loss of efficiency in real-world conditions. This means not only wind resistance, but also gravity, rolling resistance and vibration, and Zipp’s product manager Nathan Schickel says that in these last two, there are still “major gains to be had”, and the AXS Wheel Sensor enables riders to harness them. It has multiple benefits, as Schickel explains, that range from simple time-saving convenience to in-depth analysis of tyre pressures over a sector of terrain. “We all know that when you get ready for a ride, you have to inflate your tyres. If you have an unfamiliar pump, if you’re in the middle of nowhere and you’re using a mini-pump or if you’re simply in a hurry to get going, you can give your bike a shake or a bounce and that will wake up the two LEDs in the wheels,” says Schickel. A green flashing light (which shuts off automatically after 30 seconds) means the tyre is within your chosen tyre pressure range. “With a flashing red light, fast flashing red means tyre pressure is too high. Slow flashing red, too low. So it’s a three-step process that helps you quickly get out on the road. Shake to wake or give the bike a bounce,” explains Schickel. “If you’re out on a ride, you’re pushing and it doesn’t feel right, is it a flat tyre or just bad legs? If you look at your head unit it can tell you. It’s a nice way to help understand the effect of tyre pressure on how you feel.”
For more advanced analysis, The data recorded by the Wheel Sensor can be used to understand the effect of tyre pressure, “to understand how best to use that tyre pressure to optimise your ride,” says Schickel. “If you go out and you’re measuring a sector, you can measure it several times with different pressures. You can understand which pressure was too high, which too low, and calculate the effect on speed, time and power. Overall it becomes a tool to tune your ride to allow you to go faster.”
The Wheel Sensor runs on a CR2032 coin cell battery which gives around 400 days of battery life. “We’ve had 20 test riders logging over 100,000 kilometres over the last year out in the field, and they are still using the batteries they started with,” confirms Schickel.
The 353 NSW and 303 SW ship with a sealant syringe that allows sealant to be pushed into the tyre past the sensor so that each wheel can be set up correctly. And in the case of a flat that sealant can’t plug, Zipp created TPU tubes with the ported valve – also shipped with the wheels – so that riders can keep a spare, or even run the Wheel Sensor with a TPU tube from the start. Traditional butyl tubes work too, explains Schickel, as long as the valve is the threaded type, since they need the nut to hold the sensor in the wheel.
At the centre of the new 353 NSW wheels is Zipp’s new ZR1 SL hubset. Whereas Zipp has a longer history than most of developing and manufacturing cutting-edge carbon rims – the 303 was the first carbon wheel to win Paris-Roubaix in 2010 – for the hubs its parent company SRAM can leverage more than a century of expertise. In 1997 SRAM acquired Sachs, the German company that invented the bicycle freewheel, and the ZR1 SL was developed at Sachs’s Schweinfurt facility, which SRAM still uses. “We use that history every day to make sure our hubs meet the needs of discerning cyclists,” says Schickel.
Based on the ZR1 hub, billed as a “high-performance workhorse”, the ZR1 SL uses weather-resistant, low-drag ceramic bearings. Schickel explains: “The idea behind ceramic bearings is to be able to use non-contact seals so that the bearing spins as lightly as possible. That left our hub team with the challenge of finding a material for the races that was weather resistant, water resistant and hard enough to handle possible intrusions of dirt and grit. So we found a stainless steel that’s the same as that used in prosthetic hips and prosthetic knees. It’s very hard and also very corrosion resistant.” Zipp uses a saltwater intrusion test, in which a bearing is immersed in saltwater for at least 48 hours. “These ones after 96 hours do not show any signs of corrosion whatsoever. As a comparison with one of the super-high-end aftermarket ceramic bearings on the market – it costs $900 to replace all the bearings in a set of Zipp wheels with these particular ones – the competitors can only stand 24 hours in our submersion test before you start to see corrosion. So you have a massive increase in bearing life and that allows us to run super high-precision bearings that are made of ceramic, with the appropriate grease to give a smooth ride.”
For more information and pricing go to Zipp’s website.
