Understanding RC Bearing Measurements
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Bearing Sizes Explained: Understanding RC Bearing Measurements
If you’ve ever looked at an RC bearing listing and seen something like 5x11x4, you may have wondered what those numbers actually mean.
Understanding bearing sizes is one of the most important parts of maintaining, upgrading, or replacing bearings in your RC vehicle. The good news is that once you know how the sizing system works, it’s very simple.
At FastEddy Bearings, we build complete model-specific bearing kits so you don’t have to guess. But for RC enthusiasts who want to better understand their vehicles, here’s a breakdown of how RC bearing sizes work.
What Do Bearing Sizes Mean?
RC bearing sizes are typically shown in this format:
5x11x4
These numbers represent:
- 5mm Inner Diameter (ID)
- 11mm Outer Diameter (OD)
- 4mm Width
In simple terms:
| Measurement | Meaning |
|---|---|
| First Number | Hole size through the center |
| Second Number | Outside diameter of the bearing |
| Third Number | Thickness/width of the bearing |
So a 5x11x4 bearing fits:
- A 5mm shaft
- Into an 11mm bore
- With a width of 4mm
Why Bearing Sizes Matter
Using the correct bearing size is critical for:
- Smooth drivetrain operation
- Proper gear alignment
- Reduced wear
- Lower friction
- Improved performance
- Longer component life
Even being off by 1mm can prevent proper installation or cause premature failure.
Common RC Bearing Sizes
Some of the most common RC bearing sizes include:
Different manufacturers use different combinations depending on the vehicle design.
Rubber Sealed vs Metal Shielded Bearings
You may also notice letters after a bearing size.
Examples:
These letters describe the type of protection used.
Rubber Sealed (RS)
Rubber seals help keep out:
- Dirt
- Dust
- Water
- Mud
These are ideal for:
- Bashers
- Crawlers
- Off-road vehicles
Metal Shielded (ZZ)
Metal shields reduce friction slightly and are often preferred for:
- Racing
- High RPM applications
- Cleaner environments
Metric Bearings vs Standard Bearings
Most RC vehicles use metric bearings measured in millimeters.
That’s why nearly all RC bearing sizes follow the:
- ID x OD x Width format in mm
Examples:
- 5x11x4
- 8x16x5
- 10x19x5
How To Identify Your Bearing Size
There are several ways to determine your bearing size:
1. Read The Bearing
Most bearings have the size laser-etched directly on the side.
Example:
- 5x11x4
- 10x15x4
2. Measure It
Use calipers to measure:
- Inner diameter
- Outer diameter
- Width
3. Use A Complete Bearing Kit
The easiest option is using a model-specific kit from FastEddy Bearings.
Our complete kits include every bearing needed for your RC vehicle — no guessing required.
Why RC Bearings Fail
Incorrect sizing can contribute to bearing failure through:
- Excessive side load
- Poor alignment
- Heat buildup
- Contamination
- Vibration
Signs of failing bearings include:
- Grinding noise
- Increased resistance
- Slop in wheels or drivetrain
- Rust or discoloration
- Reduced run time
Choosing The Right Bearing Upgrade
When upgrading bearings, consider:
- Driving conditions
- Speed
- Water exposure
- Dirt and dust
- Racing vs bashing
Many hobbyists upgrade to:
- Rubber sealed bearings for durability
- Ceramic bearings for reduced friction
- High-quality steel bearings for long life
Final Thoughts
Understanding bearing sizes helps you:
- Maintain your RC vehicle properly
- Order the correct replacement parts
- Improve reliability and performance
Whether you’re racing, crawling, bashing, or restoring an RC vehicle, the right bearings make a huge difference.
If you want an easy solution, FastEddy Bearings offers complete model-specific RC bearing kits designed to replace every bearing in your vehicle accurately and efficiently.