Why Test Spoke Hole Strength?
Spoke holes, or nipples holes, are where a spoke is threaded into a nipple and fixed at the rim side. We call the area where the nipple pulls against the rim the “key area, or nipple bed” which needs additional reinforcement. Poorly manufactured rims are likely to crack at this high stress area due to the significant amount of tension in the spokes.
Testing Goal
Ensure that the key area around the holes has been precisely reinforced in the layup process so that there is no pull through.
Testing Standard
300kgf without hole cracks or spoke pull-through. Comparatively speaking, most wheels hold a final spoke tension of ~120kg/f.
Sample Profile
| Model | Size | Width | Depth | Measured Weight | Test Condition |
|---|---|---|---|---|---|
| AM728 | 650B | 28/34mm | 28mm | 409g | Divided into 3 rim blocks |
Test Facility
The spoke hole tensile strength is tested on the Universal Testing Machine (UTM). The machine has a rigid base with a clamping device to hold the rim firmly. Above of which is a steel clamp that pulls the spoke upward, gradually increasing in force until the spoke breaks or it pulls through the rim. Pulling force, rim deformation, and the breaking point data are recorded.
Test Conditions
| Testing Speed | 5mm/min |
|---|---|
| Spoke | Sapim Race (2.0/1.8/2.0) |
| Test Positions | 3:00, 6:00, 9:00 |
| Test Method | Destructive |
| Nipples | External Nipples |
| Hole Angle | +/-6° |
*Samples taken from 3, 6, and 9:00 positions to ensure the accurate average spoke hole strength of a specific rim is recorded.
Methodology
Specifications
The two criteria hereunder must be fulfilled during our spoke hole strength test.
1. There should be no noticeable deformation around the hole which undermines the wheel functionality at/under 300kgf.
2. After the test, the sample must remain completely intact and without any hairline cracks.
Test Results
#1 Sample
| No. | Deformation (mm) | Max Force (kgf) | Force At Breaking/Cracking (kgf) |
|---|---|---|---|
| 1 | 8.90 | 395.8 | 366.8 |
#2 Sample
| No. | Deformation (mm) | Max Force (kgf) | Force At Breaking/Cracking (kgf) |
|---|---|---|---|
| 2 | 5.26 | 395.1 | 384.6 |
#3 Sample
| No. | Deformation (mm) | Max Force (kgf) | Force At Breaking/Cracking (kgf) |
|---|---|---|---|
| 3 | 10.21 | 423.9 | 397.7 |
Conclusion
In #1 rim block, the spoke pops out at a force of 366.8kgf; in #2 block, the spoke breaks at 384.6kgf; and in #3 block, the spoke pops out at 397.7kgf. All exceed 300kgf. Test passed.
Testing with the conditions defined above will ensure our rims can withstand spoke pull forces beyond what you would encounter during hard riding.
© All photos and test data by Light Bicycle
SHARE NOW:
October 24th, 2020 | Light Bicycle
Get in touch
Feel free to leave a comment if you have any questions or suggestions on our products or other issues.
Please leave your name here.
E-mail is required for further contact.
Please enter a message.
Your Cookie Preferences
We use cookies to improve your experience on this website. You may choose which types of cookies to allow and change your preferences at any time. Disabling cookies may impact your experience on this website. You can learn more by viewing our Cookie Policy.
Cookies required to enable basic website functionality.
Cookies used to understand how the website is being used.
Cookies that are used to enhance the functionality of the website.
Cookies used to deliver advertising that is more relevant to your interests.
