Zipp 303S Disc-brake Wheelset

 

The newly launched Zipp 303 S is effectively a complete update to the existing 302 carbon wheel, a model that itself broke new boundaries for the brand via its lower price point. Like the 302, the new 303 S is aimed more at the endurance and gravel end of the spectrum rather than racing – although there’s nothing stopping you using these for that either.

 

This new 303 S however, goes one huge leap further and is the first carbon Zipp wheel to break the magic price point. But don’t call it a ‘budget’ wheel, this isn’t just an outdated, older design that Zipp has rehashed to open up the market. No, the 303 S has a completely new and up-to-date rim design that promises a lot for the rider.

 

 KEY FEATURES:

 

• New Zipp graphics and cosmetic identity that scream speed.
• Fastest with 28mm, fits wide gravel tires as well
• 76 / 176 DB hubs with Center locking interface
• XDR driver body option
• Wide rims optimize tire profile to allow lower tire pressure, especially with tubeless. The result is a larger contact patch for increase grip for confident cornering, descending, and handling in wet conditions.
• Lower tire pressures and larger volume provides a compliant ride with fewer vibrations.
• Significant watt savings when running larger tires at lower pressure.
• Wide hookless rims create a seamless transition to the tire, reducing drag.

SPECIFICATIONS:

• Size (wheels): 700c
• Rim construction: Carbon
• Tire compatibility: Clincher Tubeless Ready
• Brake compatibility: Disc (Center Lock)
• Driver body type: SRAM XDR, SRAM/Shimano Road, n/a
• Rim - inside width: 23mm
• Rim finish: UD fiber / Bake-On labels / Matte clear coat
• Rim profile: Symmetrical
• Weight (g): 1530
• Weight Based On: Lightest configuration: 12mm through axles and XDR body. No tape or valve included in weight. Front: 711g Rear: 819g 

In fact, comparing the new 303 S to the 302 is actually quite difficult, with Zipp preferring to refer to this new wheel as part of the 303 wheel family. Yes, both wheels share the same 76/176 hubs, a hub set we really rated for ease of maintenance and simple standardised construction and the rear wheel sticks to 24 spokes laced in a two-cross pattern. Everything else is different, especially the rim.

Disc only

Firdly, developing the new 303 S rim specifically for disc brakes has allowed Zipp more freedom to design the rim to be all about performance with no compromise.

Not needing to consider the rim for braking duties allowed Zipp the opportunity to focus on the critical rim and tyre transition – an area important for overall aerodynamics. Zipp came up with a pretty simple solution to aid a smoother rim and tyre transition – it got rid of the traditional inner ‘hook’ profile of the rim. By removing the hook completely this also enabled the new rim design to have a much increased internal width. Just how much difference has this made? The existing 302 has an internal rim width of 16.25mm whereas the new 303 S is boosted nearly 7mm to 23mm. Externally it’s just 2mm wider than the 302 at 27mm compared to 25mm.

Wider tires and tubeless, the new benchmark

This new rim is also designed around the recent growth of tyre widths and the wider internal measurement makes it ideally suited for use with the rapidly popularised 28mm tyre, although Zipp has also stated that it will work really well with 25mm tire widths as well as wider gravel tires.

With the increase in internal rim width Zipp was able to ensure that the profile of a 28mm tire allowed it to retain a more stable and aerodynamic ‘U’ shaping rather than what it calls the ‘lightbulb’ shaping found when using a wider tire on a narrow rim. Zipp is not alone in terms of focussing on a wider tire as standard and there has been plenty of evidence already put out that show a 28mm tire can be the fastest across a number of different tests.

This rim has also been designed to be run as a tubeless wheelset first and foremost – you can of course use tubes at a pinch, but the rim has a maximum recommended pressure of just 73 psi, making it pretty much designed for running pressures only capable when going tubeless.

Tyre pressure is also a topic Zipp want us to think about in order to maximise wheel and tyre performance – not just with the new 303 S. Zipp’s research team believes many riders are running even our tubeless tyres at way too high a pressure, so the brand has even developed a pretty comprehensive tyre pressure calculator that should be going live towards the end of the month and available for all to use, not just Zipp wheel owners.

Less weight more strength

The weight of the rim was also a big consideration for Zipp when developing the new 303 S and the result is a significant weight saving of nearly 100 grams over the 302. Bear in mind that the new wheels have the same hubs and more spokes compared to the 302, that means Zipp has managed to save that weight in the rims alone. The 302 weighed in at 1643g on our scales whereas the new 303 S weighs in at 1555g (Zipp claim 1540g).  In fact the new 303 S is lighter than the existing, far more expensive 303 Firecrest.

Zipp learnt a lot from its latest 3Zero Moto MTB wheels launched last year with regards the strength to weight ratio of its carbon rims. Obviously getting rid of the hook from the rim certainly helped drop the rim weight.