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1. Horizontal Stifness

What: Tests the horizontal stiffness of the rim when a weight is applied to side of a horizontal rim.

How: The bottom half of the wheel is secured into a fixture in a horizontal position. Pressure is then applied in a horizontal plane (load position is beside the valve) to the center of the top half, and deformation is measured.

Why: While some horizontal flex is inevitable and necessary, a horizontally stiffer wheel will enhance the wheel’s performance, especially when torqued during a sprint or during a hard corner.

2. Vertical Stifness

What: Tests the vertical stiffness when a load is applied to the top of a vertical rim.

How: The bottom half of the wheel is secured into a gauge in a vertical position. Vertical pressure is then applied to the top of the rim, and downward deformation is measured.

Why: Vertical compliance is critical to ride feel, especially over rough surfaces, and on longer rides. The ideal amount will provide just enough compliance while remaining stiff enough for maximum power transfer during hard efforts.

3. Vertical Destruction

What: Tests how much vertical load a rim can withstand before failure.

How: The bottom half of the wheel is secured into a gauge in a vertical position with the valve on the side. Vertical pressure is then applied to the top of the rim, 90 degrees from valve, and pressure is increased until crack appears in rim. Max load and type of crack are recorded.

Why: This is a good measure of the overall durability of a rim. The more pressure it can withstand, the longer it should last on the road.

4. Spoke Hole Pull-Through

What: Tests the strength and integrity of the spoke holes.

How: A 2mm steel line with a steel head attached is laced through a spoke hole. The end of the line is attached to a tension gauge, then it is pulled until a crack forms in the spoke hole or the line comes free completely.

Why: High numbers in this test mean a more durable and well-built wheel. * Our spoke holes are reinforced with a pre-molded carbon insert to address this issue, and can withstand pull strength far beyond industry standards.

5. Vertical Impact

What: Tests the pressure at which a rim will fail due to vertical impact.

How: A weight is hung above a secured rim and dropped directly onto the top of the rim. Increasing weights are dropped until the impact meets UCI standard of 355.8 joules. A wheel passes if no damage occurs at this impact.

Why: Simulates the impact on a wheel during a crash, or running into a curb at high speed.

6. Rim Fatigue

What: Tests the fatigue life of a wheel under bumpy conditions.

How: A wheel and tire (inflated to 120psi) are spun at 40kph by a rotating cylinder with 5mm raised “blocks” placed every 400mm. A standard load, 60kg front and 90kg rear, is placed on the wheel and kept constant throughout the test. The cylinder continues to spin and jar the wheel until failure. To pass this test, a wheel should have no visible damage to the rim or hardware, or air loss due to leakage from the bead after.

Why: This simulates real-life riding conditions and ensures quality rim construction and build.

7. Brake Track Failure

What: Brakes are repeatedly applied and released to test the brake track durability and heat resistance.

How: A rim is placed in the test rig and with a load of 100kg. It is then rotated constantly at 12.5kph, while the brakes are engaged and disengaged at a set pressure every 3 seconds. Rims should endure 3000 cycles of braking with no sign of failure to meet industry standards.

Why: This tests how well the rim can withstand the heat generated from braking on the carbon track.

8. Deformation

What: Measures the expansion of the rim bead when under pressure from an inflated tire.

How: Three separate steps:

  1. Security test: Measure the rim with an inflated tire (145psi) at three points, and let sit for 24 hours. Deflate the tire and measure again: measurements should be the same.

  2. Deformation test: Measure the rim width at the spoke holes. Inflate the tire to 130psi. After 10 minutes check the rim width again at the same points. At least three points should have less than .05mm of deformation.

  3. Blowout: Inflate a tire to 102psi, then pause 60 seconds and listen for noise. Inflate by 7.5psi more and repeat. There should be no noise until 170 psi. Noise is ok until 170 psi but no blowout or breakage is acceptable.

Why: This test ensures that rim beads can handle well above the maximum inflation levels for road tires.

9. Roundness

What: Tests the rotational “roundness” of the rim without a tire.

How: The rim is placed in testing flat, with a measuring device on the outer edge at the rails. Measurements are taken continuously as the rim rotates 360 degrees. The rim can only vary by no more than 0.4mm throughout the rotation.

Why: If a rim comes out of the box with major imperfections in the roundness, spokes will not be able to correct and/or maintain the roundness of the wheel. A more perfectly round wheel means a smoother and more controlled ride.

10. Flatness

What: Tests the “true” of the rim before laced.

How: The rim is laid flat on a granite surface. Measurements are taken continuously around the rim between the rim and the surface. The rim should remain less than or equal to 0.4mm from the surface throughout the rotation.

Why: If a rim is not true when it comes out of the box, the spokes will not be able to correct and/or keep it in true. This means less maintenance on the rim when built up, smoother and more reliable braking, and a more controlled ride.

11. Spoke Hole Positioning

What: Tests to assure the spoke-hole angles have been drilled precisely at predetermined position and angle.

How: The rim is fixed in a testing device and rotated while a gauge measures the exact position and angle of the spoke holes. Each hole must be drilled to exact specification.

Why: At Knight Wheels, we drill our holes at the precise angle at which the spoke must travel to the hub. The more accurate the spoke-hole angle is the less tension on the spoke, which results in a more reliable true and less spoke breakage. This means lower maintenance and a better ride.

12. Rim X-Ray

What: Tests for inner defects in manufacturing that would otherwise be impossible to catch.

How: The rim is fixed to a special gauge and rotated while an X-ray machine takes images of the complete interior of the carbon walls. The images are reviewed to look for miniscule cracks or imperfections. To maximize consistency, 10% of the rims are tested through this process.

Why: Tiny imperfections can occur during the production process. Although they are invisible to the human eye, they could negatively affect the ride quality, safety or durability of our rims. Whilst this test is costly, we want to assure that every one of our wheels is as close to flawless as possible.