Zipp’s Total System Efficiency (TSE) wheel-design is based on a simple premise: Efficiency equals speed. The combination of a new rim laminate with a wider rim profile optimized for tire interface, transforms your ride experience to overcome the four barriers to speed: wind resistance, gravity, rolling resistance, vibration losses.
Just how effective is TSE? Outdoor testing at commissioned by Zipp revealed the real-world gains of Zipp Total System Efficiency (TSE) at 40kph. The 454 NSW with TSE™ required a 10-watt savings to maintain that speed compared with the previous model. The 404 Firecrest TSE showed a 4 watt savings.
TSE approach is a balanced attack against the four barriers to speed:
These four enemies of speed are present, to varying degrees, in all road-cycling disciplines. TSE-designed wheels are optimized to make you faster no matter road surface or discipline (Use color code above to see barriers to speed in specific cycling disciplines):
Our Solution: Conquering wind resistance through gains in aerodynamic efficiency and crosswind stability is Zipp’s longtime forte with our industry-changing Firecrest and Sawtooth NSW rim shapes. In modern road bikes, 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 inefficiency.
Our Solution: Zipp wheels with TSE are remarkably lighter, about a pound lighter in the case of the 454 NSW. With advanced in our carbon manufacturing, Zipp designs wheels with massive weight savings. The 454 NSW Tubeless Disc-brake wheelset is roughly a pound (more than 400 grams) lighter than its predecessor! Typically, weight reduction comes at the price of durability. Yet, the design, rim laminate, and manufacturing process used on TSE-designed wheels provides robust durability at a lighter weight.
Our Solution: Perhaps you remember this from physics class: pressure = force distributed over an area. In cycling, the tire-contact patch area is determined by the rider’s 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 patch. 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. 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. Improving rolling resistance has the same magnitude of impact on overall efficiency as choosing the right rim shape.
Our Solution: Using a new rim laminate, we design Zipp wheels to be versatile: They can be ridden on traditional roads, but they are also capable of tackling harder terrain including rough roads, light gravel, and—of course—the cobbles of the Spring Classics. We designed wheels with wider tire beds to be run at lower tire pressures to smooth out the ride.
LESSONS FROM ZIPP’s ROLLINGROAD™
In developing TSE, Zipp engineers set up a “RollingRoad™” to duplicate surface conditions cyclists encounter in the real world in our test lab. The Rolling Road™ allows us to capture data to analyze the efficiency of different bike setups over various surfaces.
Riding with low pressure , our rider (right) is calm and focused. Riding with high pressure, our rider (left) is visibly uncomfortable and laboring to maintain control of the bike. The whole-body vibration seen here stems from the amount the tires can 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 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. The tests measured the power required to ride 32kph (20mph) over various surfaces. We captured energy 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.
TIRE PRESSURE ROAD RIDING RECOMMENDATIONS
Recommendations are a starting point for riders to begin tuning their optimum tire pressure setups for road riding.
Front/rear PSI recommendations