BMX Race Rims
BMX race rims come in various diameters and widths – depending on rider type, age, and area of use. You’ll find an overview of the most common combinations in BMX racing in our FAQ section.
BMX Race Rims FAQBMX Race Rims stuff
BMX Race Rims FAQ
Overview Table: BMX Race Rim Sizes & Use Cases
Key measurements for BMX race rims include the ETRTO diameter (e.g. 406 mm or 451 mm) and the rim width, which determines which tires will fit. Below is an overview of the most common combinations used in BMX racing.
| Category | Wheel Size | ETRTO Ø | Rim Width (external) | Typical Tire Width | Use Case |
|---|---|---|---|---|---|
| Micro / Mini | 18" | 355mm | approx. 18–21 mm | 18" × 1.00" – 18" × 1.25" | Smallest riders, ultra-light setups |
| Junior / Expert | 20" (JR/EXP) | 451mm | approx. 19–22 mm | 20" × 1-1/8" – 20" × 1-3/8" | Kids & teens, race-optimized |
| Standard 20" | 20" | 406mm | approx. 25–32 mm | 20" × 1.40" – 20" × 2.10" | Standard race setups, wider tires possible |
| OS20 | 20" (OS20) | 451mm | approx. 23–28 mm | 20" × 1.60" – 20" × 1.75" | Taller riders, high-volume race setups |
| Cruiser | 24" | 507mm | approx. 25–32 mm | 24" × 1.75" – 24" × 2.10" | BMX cruiser class, youth & adults |
OS20 – 20" but Bigger!
What is OS20?
OS20 is a 20-inch BMX wheel size with a larger diameter of 451 mm (compared to the usual 406 mm for 20"). It offers similar widths to standard 20" race wheels.
Are OS20 tires and rims compatible with Expert sizes?
No. OS20 tires and rims are not compatible with the narrower 451 mm rims used in Junior/Expert setups.
Is OS20 allowed in BMX racing?
Yes, OS20 wheels and tires comply with UCI BMX sizing regulations for 20".
What parts do I need for OS20?
You’ll need an OS20-specific frame, OS20 wheels and OS20 tires (including OS20 rim tape and OS20 tubes). Many standard 20" forks are compatible.
What are the advantages of OS20?
OS20 rolls faster and carries momentum better due to a stiffer tire casing and smaller contact patch. This can translate into higher top speed and improved efficiency when maintaining speed.
ETRTO – European Tyre and Rim Technical Organisation
ETRTO stands for European Tyre and Rim Technical Organisation. It refers to a standardized size specification that ensures precise and reliable compatibility between tires and rims.
How is ETRTO defined?
The number consists of two parts, XX-XXX, e.g., 16-451:
- 16 = Tire width in millimeters
- 451 = Inner diameter of the rim (where the tire seats), also in millimeters
The ETRTO Diameter (⌀)
In our shop, you can filter by ETRTO diameter. This refers to the last 3 digits of the ETRTO standard, since tire width is not relevant for rim compatibility.
ERD – Effective Rim Diameter
ERD stands for "Effective Rim Diameter" and refers to the inner diameter of the rim – the circle formed by the centers of the spoke holes on opposite sides. This measurement is essential for calculating the correct spoke length when building wheels, as it determines how far the spoke extends into the rim.
