Z3 and Z4 Hubs The ZIPP Z3 and ZIPP Z4 wheelsets require a very special set of hubs. Available only as original equipment on the Z3 and Z4 wheels, the model 175 rear and 70 front hubs are the no-holds-barred realization of cutting edge hub technology.

The ultimate hub has to have the ultimate bearings. Silicon Nitride (Si3N4) ceramic bearings are 30% lighter than steel and 40% stronger. So finely balanced, they have an incredible maximum spin rate of 300,000 rpm under load. Manufactured in matched sets of 12 to 15 balls per bearing, they exhibit variance in size and sphericity of LESS than 1 millionth of an inch among the entire bearing set. Each ball is over 1000 times more round than the best steel bearing of any type, grade or benchmark. At 25mph, the calculated energy saving from these alone is 0.8 to 1.0 watts. On an 8% grade, the reduction in friction is the equivalent of a reduction in static weight of 340 grams! A custom Teflon thermoplastic retainer physically separates and locates each individual ball within the bearing race for optimum performance and longevity. Further protection is provided by a custom formulated 65% fill barium-hydrocarbon ceramic specific grease. Double non-contact seals on polished races provide a final near friction free protective barrier against the elements. The bearing races themselves are a hybrid ceramic specific alloy finely ground and polished to a ISO class 9 or better standard, then cryogenically treated at -300 degrees Fahrenheit to refine the molecular structure.

The 175 rear and 70 front hub shells, axles and end caps are precision machined using Alcoa 7075 military spec ordinance grade alloy. Freehub bodies for the rear hubs are machined from 7XXX alloy, a recently declassified material with 33% greater strength and 40% greater hardness than the previous industry benchmark of 7075 aluminum. 7XXX alloy from Alcoa meets or exceeds the capabilities of 7075 in every measurable area.

The clutch mechanism engages with authority. Three forged low friction E52100 bearing steel pawls are actuated by a single oversized stainless steel return spring for quick transition from coasting to power application. The axle is high-density filament wound Carbon fiber married to 7075 ends. The asymmetric 15mm axle front and rear is 25% larger than is standard and designed for optimized bearing placement, strength and significant weight reduction. Protective Carbon fiber end caps shields the internal mechanism from the elements.

Model 70 front hub:

• 70 grams
• Precision machined 7XXX military ordinance grade hub shell.
• Silicon Nitride (Si3N4) matched ceramic bearings. Less than 1 millionth of an inch total size and sphericity variance per matched set.
• Carbon fiber axle
• 7XXX alloy axle ends
• Carbon fiber protective end caps.
• Drilled 18 hole only.

• 175 grams
• Precision machined 7XXX military ordinance grade hub shell and free hub body.
• Shimano and Campagnolo versions. Interchangeable for full cross-system compatibility.
• Silicon Nitride (Si3N4) matched ceramic bearings. Less than 1 millionth of an inch total size and sphereicity variance per matched set.
• Carbon fiber axle
• 7XXX alloy axle ends
• Carbon fiber protective end caps.
• 24 hole only