Spoke Hole Pull-Through Test: Ensuring Resistance to Extreme Tensions

The spoke hole area—the inner circumference where the nipples are seated—is a critical part of a rim’s structural integrity. To strengthen this area, manufacturers typically reinforce the rim either by adding continuous layers around the circumference or by reinforcing each individual spoke hole. While the former method is faster, it tends to add unnecessary weight and uses more material. The latter, though more precise and time-consuming, is a more efficient way to reduce weight while maintaining strength. Regardless of the approach, ensuring that the spoke holes can withstand high tension forces is essential to maintaining the overall performance and safety of the wheel.

Test Standard

At NTP, our rigorous testing standard requires that no spoke hole crack under a load of 350kgf. Typically, spoke pull-out forces exceed 420kgf. However, we offer customized testing standards based on specific performance requirements for our clients' products.

Test Goal

The goal of the spoke hole pull-through test is to assess the rim's ability to resist extreme forces applied by the spokes. During aggressive riding, some spokes may experience very high tensions, which could potentially damage the rim and compromise the wheel’s integrity—rendering it unrideable and possibly unsafe for the rider. The test ensures that the rim holes can endure these forces without failure.

Test Equipment

We utilize a Universal Testing Machine (UTM) for the spoke hole tensile strength test. The UTM features a rigid, curved base that matches the shape of the rim’s inner circumference, as well as a compression rig and ejector pin to apply a controlled load to the spoke holes. The sensor integrated into the compression rig automatically records the applied pulling force during the test.

Test Method

Step 1: Sample Preparation: The rim is cut into 6 to 10 evenly sized pieces to ensure balanced performance across all spoke holes.
Step 2: Initial Setup: A sample rim cutaway (Cutaway #1) is placed securely onto the testing rig. The compression rig is lowered, and the ejector pin passes through the rim bed to make contact with the spoke hole.
Step 3: Test Execution: The compression fixture applies downward force at a controlled rate. The force gradually increases until the ejector pin pulls through the rim hole.
Step 4: Repetition: Once the first test is completed, the rim cutaway is replaced with the next section, and the process is repeated until all sections are tested.

Sample Test Report

Example Profile

Model	Size	Width	Depth	Weight (Stated)	Measured Weight
G28-45	700C (622-28)	28.5/34.1mm	45mm	400g	395g

Test Report

Cutaway No.	1	2	3	4	5	6
Breakage Force	435.58kgf	434.90kgf	440.25kgf	438.45kgf	436.64kgf	441.02kgf
Average Breakage Force	437.8kgf
Result	PASS	PASS	PASS	PASS	PASS	PASS

For all six rim cutaways, the average spoke and rim disassembling force was 437.8kgf, which exceeds the required 350kgf standard, confirming the strength and durability of the spoke holes.

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Email: koko@ntpcomposites.com
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NexusTech Prime (NTP) Composites

Established in 2013 initially as an OEM carbon rim contract manuafacturer, NTP composites has grown steadily to be a full-service OEM and ODM service provider, with brilliant quality control, proficient engineering capability, and excellent customer service.

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