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Our 303 Firecrest and 353 NSW Tubeless wheelsets are designed to achieve Total System Efficiency (TSE™). Based on the simple premise of “Efficiency = Speed,” TSE™ is our solution to speed in the real world... a world of imperfect roads and changing riding conditions.



Going faster on or off pavement is all about efficiency – more speed for less power. The combination of a larger tubeless tire, lower tire pressure, a wider rim profile optimized for tire interface, and a new rim laminate all come together to create a more efficient ride. When applied to bikes, efficiency means reducing the effort to overcome:

  • Wind Resistance
  • Gravity
  • Rolling Resistance
  • Body Vibration Losses


Disc-brakes improve stopping power, but they also help you increase speed. The absence of rim-brake calipers allows for a wider rim profile with a smoother tire to rim interface for optimum aero performance with larger tires that provide a net gain in efficiency.

GRAVITY (Weight vs Durability)

Gravity is relentless, and light weight components have long been a focus for any cyclist. As soon as the road points uphill, weight becomes a significant factor against speed. The 353 NSW is our lightest ever non-tubular wheelset. Current 303 models see a significant reduction in weight coming solely from the rim, making the wheels extremely nimble. We focused on reducing the weight of this wheel because we understood that lightweight wheels are a priority for the modern road cyclist customer. The new 303 Firecrest is 300 grams (20%) lighter than its predecessor. Typically, lighter weight comes at the price of durability. Yet the design and manufacturing process used on the 303 provides robust durability at a lighter weight.

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Perhaps you remember this from physics class: pressure = force distributed over an area

Or, in simple terms, area = force/pressure.

In cycling, this is a useful equation. The tire-contact patch area is determined by the rider weight and your tire pressure. If you got on two different bikes with two different width tires, but the same tire pressure on both bikes, the contact patch of the different tires would match, because both tires are supporting the same load with the same pressure. The only difference in these two scenarios is the SHAPE of the contact path. A wider tire will produce a wider and shorter contact patch compared to a narrow tire.

There are two ways to make a tire wider – get a bigger tire or get a rim with a wider tire bed.

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Wider rim + wider tire = wider and shorter tire contact patch. This promotes less tire sag, which deforms the tire less, resulting in less energy lost in the rolling tire.

Is rolling resistance an important consideration?  Yes! Improving rolling resistance has the same magnitude of impact on overall efficiency as choosing the right rim shape.

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Modern road bikes are versatile: They can be ridden on traditional roads, but they are also capable of tackling harder terrain including rough roads, light gravel or even the cobbles.

To understand what makes the fastest wheels over such a wide range of conditions.


The RollingRoad™ duplicates surface conditions cyclists encounter in the real world. This test rig allows us to capture data to analyze efficiency of different bike setups over various types of surfaces.

Riding at low pressure on the right, our rider is calm, collected, and focused. Riding at high pressure on the left, our rider is visibly uncomfortable and laboring to maintain control of the bike. The whole-body vibration seen here stems from the amount the tires are able to absorb the bumps. More pressure leads to more vertical displacement. Low pressure cuts out road input significantly.

Smoothing the Ride 

Vertical displacement robs energy from the system and goes right into the rider’s body. Look at the arms in these two different setups: That muscle moving back and forth violently is soaking up power from the system. The human body is acting like a big damper system. The less you vibrate the damper, the less energy you lose to vibration.

Your next question should be, "So what?" How much power loss are we talking about? 1 watt? 3 watts?

PSI vs. Power

Data from our RollingRoad™ tests show the difference between ultra-low pressure and high pressure can account for 50 watts in efficiency gains on a rough road. These tests, which measures power required to ride 32kph (20mph) over various surfaces, capture power lost to tire deformation, drivetrain, and whole body vibration.

The order of magnitude of this type of loss warrants your attention. As surface roughness increases, you want to run larger tires at lower pressures. We advocate using a tubeless setup to capture full benefits. Pinch flats are much less likely at low pressure when running tubeless. Added benefits of a wider tire at lower pressures are better handling and cornering. Your tires will not skip off small bumps and lose traction while cornering.

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The 303 Firecrest has a max tire pressure of 72.5psi (5 bars)


Recommendations are a starting point for riders to begin tuning their optimum tire pressure setups for road riding.

Front/rear PSI recommendations

Zipp Tire Pressure Guide


Dig the science? A Deep Dive Below

TSE White Paper

ZIPP Hookless Technology