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When a worn headset, bottom bracket, or wheel hub starts introducing drag and play into your ride, the culprit is often degraded or undersized loose balls. Cyclists, mechanics, and DIY equipment builders who need an exact replacement or a bulk supply of carbon steel balls will find this listing covers the widest practical size range in a single place.
These carbon steel loose ball bearings are available in metric diameters from φ1mm (≈0.039") up to φ13mm (≈0.512"), as well as common imperial sizes including 1/8", 3/16", 7/32", and 1/4". Each ball is manufactured from carbon steel, offering a balance of hardness and toughness suited to radial and thrust load applications. Quantity options run from a single sample piece through 50, 100, 200, and 500-piece packs.
Typical use cases include bicycle headset and bottom bracket repacking, wheel hub servicing, small machinery and skateboard bearing replacement, and prototype or hobby mechanical assemblies requiring carbon steel loose ball bearings in precise metric or imperial diameters.
| Material | Carbon Steel |
|---|---|
| Diameter Range (Metric) | φ1mm – φ13mm (see variant options) |
| Diameter Range (Imperial) | 1/8", 3/16", 7/32", 1/4" (see variant options) |
| Surface Finish | See variant options |
| Hardness | See variant options |
| Pack Quantity | 1 / 50 / 100 / 200 / 500 pcs (see variant options) |
| Condition | New |
| Typical Applications | Bicycle headsets, bottom brackets, wheel hubs, light machinery, hobby assemblies |
| Load Type | Radial and thrust (light to moderate) |
| Corrosion Resistance | Contact us to confirm |
Remove one existing ball from the bearing race and measure its diameter with a digital micrometer or caliper. Match that measurement to the closest size in the variant list. For cup-and-cone bicycle bearings, common sizes are 1/4" (6.35mm) for front hubs, 3/16" (4.76mm) for rear hubs and headsets, and 1/8" (3.175mm) for some older headsets. When in doubt, measure — do not estimate by eye.
Carbon steel balls used in bearing applications are typically hardened to resist surface fatigue under rolling contact stress. These balls are suited to the moderate loads found in bicycle headsets, bottom brackets, and wheel hubs. For high-speed industrial spindle bearings or heavy radial loads, chrome steel (52100) balls are generally preferred. If you need hardness certification data, please contact us to confirm.
Carbon steel is susceptible to surface oxidation when exposed to moisture without a protective coating or grease. For bicycle applications, always pack the bearing race with a water-resistant grease before installation. If you ride in wet conditions frequently, consider regreasing more often. For environments with continuous water exposure, stainless steel balls may be a better long-term choice — contact us to confirm availability.
No. All balls in a single bearing race must be the same diameter. Mixing sizes creates uneven load distribution, accelerates race wear, and introduces play and vibration. If you are unsure of the correct size, measure all existing balls and replace the full set with balls of the same measured diameter.
The number varies by component. A typical threaded headset uses 11–22 balls per race (top and bottom), while a standard front hub uses 9–10 balls per side and a rear hub uses 9–11 balls per side. Count the balls removed from your bearing before ordering, then add 10–20% extra to account for any that are damaged or lost. The 50-piece pack is usually sufficient for a full headset repack; the 100-piece pack covers a complete hub service.
Only when the dimensions match exactly. For example, 1/4" equals 6.35mm and φ6.35mm balls are interchangeable. However, φ6mm and 1/4" are not interchangeable — the 0.35mm difference will cause improper fit and accelerated wear. Always verify the exact diameter before substituting a metric size for an imperial one or vice versa.
Loose balls sit directly in the cup-and-cone race without a retainer, allowing more balls to fill the race and increasing load capacity. Caged bearings hold balls in a fixed retainer ring, making installation easier and preventing ball drop-out during assembly. Most traditional threaded bicycle headsets and cup-and-cone hubs use loose balls. Cartridge bearings (sealed units) are a separate category and are not compatible with loose ball replacement.
