What’s the Difference Between 7mm & 8mm Bearings?
If you’re shopping for roller skate or skateboard bearings, you’ve probably come across 7mm and 8mm bearings. At first glance, they seem almost identical, but choosing the wrong size can lead to compatibility issues, performance differences, and frustration.
So, what’s the real difference between 7mm and 8mm bearings? And more importantly, which one is right for you? In this guide, we’ll break it all down, so you can make an informed decision and ensure your skates or board roll smoothly.
1. The Key Difference: Axle Size Compatibility
The main difference between 7mm and 8mm bearings is the size of the inner bore (the hole in the center of the bearing).
- 7mm Bearings → Have a 7mm inner diameter, designed for 7mm axles.
- 8mm Bearings → Have an 8mm inner diameter, designed for 8mm axles.
Most modern roller skates and skateboards use 8mm axles, which means 8mm bearings are the standard size. However, some older skates, high-end artistic skates, and certain roller derby setups still use 7mm axles, requiring 7mm bearings.
2. Which Bearings Do You Need?
If You’re a Roller Skater
- Most modern skates use 8mm bearings. If you have skates from brands like Riedell, Sure-Grip, Moxi, or Impala, you likely need 8mm bearings.
- Some high-end artistic skates or classic setups use 7mm bearings. If you’re unsure, check your skate manufacturer’s specifications or measure your axle.
If You’re a Skateboarder
- Skateboards almost always use 8mm bearings. There’s no real debate here—8mm is the standard for skateboarding.
How to Check Your Axle Size:
Not sure whether your skates or skateboard use 7mm or 8mm axles? Here’s how to check:
✔️ Remove your current bearings and look for engraved size markings. Most bearings will indicate their size (e.g., 608 for 8mm, 627 for 7mm).
✔️ To check if you need a 7mm bearing, try inserting a #2 pencil through your old set; if it doesn’t through, you have a 7mm bearing.
3. Performance Differences Between 7mm & 8mm Bearings
Aside from compatibility, you might be wondering, does one size perform better than the other? The answer is yes, but it depends on your skating style.
8mm Bearings: The Industry Standard
✅ Widely available & easy to replace
✅ Works with almost all modern skate setups
✅ Durable and designed for high-impact skating
✅ Compatible with most wheels, spacers, and hardware
Best for:
- Skateboarders
- Roller derby players
- Outdoor skaters
- Casual rink skaters
7mm Bearings: Niche but Lightweight
✅ Slightly lighter weight (some skaters claim they feel faster)
✅ Used in high-end artistic and precision skating
✅ Rare, but some say they have a smoother feel
Best for:
- Competitive artistic skaters
- Vintage roller skate setups
- Skaters who specifically need 7mm axles
💡 Important note: The performance difference is minimal for most skaters. If your setup requires 7mm bearings, go with them. But if you’re choosing between the two and have an 8mm axle, stick with 8mm bearings for better durability and ease of replacement.
4. Why Beagle Bearings Offers Both 7mm & 8mm Bearings
At Beagle Bearings, we know that skaters have different needs, and choosing the right bearings is essential for performance and longevity.
✔️ 8mm Beagle Bearings – Our most popular option, designed for modern roller skaters and skateboarders who need speed, durability, and smooth rolling.
✔️ 7mm Beagle Bearings – Specifically crafted for artistic skaters and vintage roller skates that require 7mm bearings.
Our bearings are made with high-precision engineering, pre-lubed for maximum performance, and built to last through intense skating sessions.
5. Common Myths About 7mm vs. 8mm Bearings
❌ Myth #1: 7mm Bearings Are Always Faster Than 8mm
Some artistic skaters claim that 7mm bearings roll faster due to their slightly smaller size, but in reality, bearing speed is more about quality and maintenance than the inner diameter. A high-quality 8mm bearing will outperform a low-quality 7mm bearing every time.
❌ Myth #2: 8mm Bearings Are Only for Skateboards
While 8mm bearings are standard for skateboards, they are also the go-to choice for roller derby, outdoor skating, jam skating, and rink skating. The majority of modern roller skates use 8mm axles, making 8mm bearings the most common choice.
❌ Myth #3: You Can Use 8mm Bearings on 7mm Axles
Nope. Your axle size must match your bearing size. If you try to use 8mm bearings on a 7mm axle, they won’t fit properly, leading to wobbling, poor performance, and potential damage to your skates.
6. Final Verdict: Which Should You Buy?
If your skates or board use 8mm axles, stick with 8mm bearings—they’re the most durable, widely available, and work with most modern setups.
If your skates have 7mm axles, you’ll need 7mm bearings to ensure a perfect fit. Be sure to check your axle size before purchasing to avoid compatibility issues.
Recap: Choosing the Right Bearings
| Bearing Size | Best For | Pros |
|---|---|---|
| 8mm Bearings | Most modern roller skates & all skateboards | Durable, widely available, fits most setups |
| 7mm Bearings | Artistic skaters, vintage skates | Lighter weight, used in high-precision skating |
At Beagle Bearings, we offer both 7mm and 8mm options so you can get the perfect fit for your skates.
7. Ready to Upgrade? Get Beagle Bearings Today!
Now that you know the difference between 7mm and 8mm bearings, make sure you’re choosing the right size for your skates.
🔥 Why Choose Beagle Bearings?
✔️ Precision-engineered for performance & durability
✔️ Pre-lubed for fast, smooth rolling
✔️ Available in both 7mm & 8mm sizes
✔️ 10% of every sale goes to animal shelters
👉 Get your Beagle Bearings today!
Final Thoughts: Don’t Guess! Measure Your Axles & Get the Right Bearings
Choosing between 7mm and 8mm bearings isn’t complicated once you know your axle size. Before you buy, double-check your skates’ specifications or measure your axles to ensure a perfect fit.
Beagle Bearings makes it easy by offering both 7mm and 8mm high-performance bearings, so no matter your setup, you’ll get a smooth, fast, and reliable ride.
Roll with confidence. Roll with Beagle Bearings. 🚀