Impact testing is essential for optimizing the quality and reliability of carbon wheels to to evaluate the durability and performance of the wheels under simulated real-world conditions, ensuring they meet industry standards for safety and performance.
Testing Procedure
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Test Equipment:
- A drop tower equipped with a calibrated impact hammer.
- Load cells to measure the force applied during impact.
- High-speed cameras for visual analysis of the impact.
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Test Setup:
- Each wheel was mounted securely to replicate real-world mounting conditions.
- Various impact angles and heights were tested to assess resilience.
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Impact Testing:
- A series of impacts were performed at designated heights (e.g., 30 cm, 50 cm, 70 cm).
- Each impact was recorded, focusing on deformation, cracks, and overall integrity.
Test Standard
(1) Must get a pass result. Simulates an impact during normal riding conditions.
(2) At 83 Joules, no wheel crack nor lateral/radial run-outs over 0.5mm.
(3) Increase the strike force beyond 83 Joules.
(4) Discover the energy level that cracks the L5 wheel.
Sample Wheel Detail
| Size | Model | Width | Depth | Rim Weight | Spokes | Spoke Tension | Wheel Condition |
| 700C | L5 | 28mm | 50mm | 380g | Carbon | 130kgf | Well trued & stress relieved |
Specifications
We test with two purposes: to ensure that the wheel remains unaffected at a regular strike (the energy level we set is much higher than the UCI standard); and to explore the impact endurance of the L5 wheel. These three criteria must be fulfilled during the impact test.
1. The rims must have passed the basic tests of trueness and stiffness before wheel building. The wheels must be well tensioned without any twist in the spokes and stress relieved before testing.
2. After the impact of 80J (usability level for L5), there should be no rim crack, and the lateral/radial run-outs must be within 0.5mm. The wheel should be safe to hit the road.
3. When the crack on the rim is too minimal to affect the real riding, we would continue the test until a bigger crack occurs and see the energy difference between the two cracks. But the force we record as the maximum impact force for the test sample is the force that causes the first crack (minimal or obvious).
Test Results
After the 80J impact, the L50 wheel looks unaffected (no rim crack; lateral/radial run-outs within 0.5mm). When the impact force reaches 100J, an obvious rim crack occurs at the hit point. The ultra impact force that this L5 wheel (without tire) can endure is about 100J.
