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When worn or undersized bearing balls cause play, noise, or premature hub failure, finding the exact replacement diameter matters. Cyclists, mechanics, and precision equipment technicians who need tight-tolerance rolling elements in the 6.35–6.4mm range will find this pack covers eleven incremental sizes in a single order.
Each pack contains 100 pieces of G10-grade Gcr15 high-carbon chromium steel ball bearings. Diameters span 6.35mm (0.250 in) through 6.4mm (0.252 in) in 0.005mm steps, allowing precise matching to worn races. The Gcr15 alloy delivers a surface hardness typically in the 60–66 HRC range and a smooth, lapped finish consistent with G10 tolerance class.
Typical applications include bicycle bottom bracket and hub bearing replacement, inline skate wheel bearings, small electric motor spindles, and precision jig or fixture assemblies where exact ball diameter determines running clearance.
| Material | Gcr15 High-Carbon Chromium Bearing Steel |
|---|---|
| Precision Grade | G10 |
| Diameter Range | 6.35mm – 6.4mm (0.250 in – 0.252 in) |
| Diameter Increments | 0.005mm steps (6.35 / 6.355 / 6.36 / 6.365 / 6.37 / 6.375 / 6.38 / 6.385 / 6.39 / 6.395 / 6.4mm) |
| Diameter Tolerance (G10) | ±0.003175mm (±0.000125 in) |
| Surface Hardness | Typically 60–66 HRC |
| Surface Finish | Lapped, consistent with G10 class |
| Quantity per Pack | 100 pieces |
| Packing Qty | See variant options |
| Application | Bicycle hubs, bottom brackets, inline skates, small motors, precision fixtures |
| Weight (per pack) | See variant options |
Measure the diameter of the existing balls with a micrometer or digital caliper. If the balls are worn, measure the race groove width and subtract the designed clearance (typically 0.005–0.015mm for bicycle hubs). Select the variant whose diameter matches your measurement. When in doubt, order one size up and one size down to test fit before committing to a full replacement.
G10 is a precision grade defined by ABMA/ISO standards. It specifies that the diameter deviation of any single ball from the nominal size is within ±0.000125 in (±0.003175mm), and the variation between balls in the same lot is similarly controlled. G10 is suitable for most bicycle and light machinery applications where smooth running and low noise are required.
Gcr15 provides moderate corrosion resistance due to its chromium content, but it is not stainless steel. For applications exposed to water, mud, or salt, apply a light bearing grease or oil after installation and consider sealed bearing housings. Regular maintenance will significantly extend service life in wet environments.
Yes. The 6.35–6.4mm diameter range is common in inline skate wheels, small electric motors, precision jigs, and light industrial spindles. As long as your bearing race is designed for balls in this diameter range and the G10 tolerance class meets your application's requirements, these balls are a direct replacement.
Each variant differs by 0.005mm. Start by measuring your existing balls or race groove. If you are replacing worn balls, you may need to go 0.005–0.01mm larger than the original nominal size to restore proper preload. If you are unsure, contact us with your bearing model or race dimensions and we can recommend the correct variant.
Each pack contains 100 pieces of the selected diameter. This quantity is sufficient for multiple bearing sets on a bicycle or a workshop stock supply. If you require larger quantities for commercial or fleet maintenance use, please contact us to confirm availability and pricing for bulk orders.
