Here is a list of the known various bottom bracket types/sizes as well as hub bearing sizes you get for anew standard BMX types. (Mid BB, Spanish, Euro)
This should be helpful when ordering or looking for replacements.

How to find out your bearing size!
Most if not all bearings have the size printed on the seal of the bearing, if not on the seal, then its laser etched into the bearing itself. See image below. The size is printed in numbers, then the code/ style/ type of bearing comes after.
So the code may be “6908”and the style of bearing “2RS” or “ZZ”.
ZZ indicates Steal Seal or a metal, non-water proof seal.
2RS indicated 2 rubber seals, water resistant.

Using the diagram below you can see how to measure your bearing and select the right size below.

I.D: Inner Diameter

O.D: Outer Diameter

W: Width

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** Mid Bottom Bracket ** BMX Specific
Mid 19mm / R12 2RS
ID: 19mm
OD: 41mm
Special size/ BMX Specific: Yes (Not available from local bearing shops)

Mid 22mm / R12RS-22
ID: 22mm
OD: 41mm
Special size/ BMX Specific: Yes (Not available from local bearing shops)

Mid 24mm / TBA
ID: 24mm
OD: 41mm
Special size/ BMX Specific: Yes (Not available from local bearing shops)

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** Spanish Bottom Bracket ** BMX Specific
Spanish 19mm / 6904
ID: 19mm
OD: 37mm
Special size: Yes (Not available from local bearing shops)

Spanish 22mm / 6904
ID: 22mm
OD: 37mm
Special size: Yes (Not available from local bearing shops)

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** Euro Bottom Bracket aka Threaded type **
Euro 22mm / 8539
ID: 22mm
OD: 32mm
Special size: Yes

Euro 19mm / TBA
ID: 19mm
OD: 32mm
Special size: Yes

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Hub Bearings:

Primo N4 front hub bearing – 6000 2RS
ID: 10mm
OD: 26mm
Special size: No

Primo Mix, Remix driver, Fit Flow driver, KHE Astern/Geisha driver, Odyssey Hazzard driver, Bicycle Union driver, Joytech driver – 6802 2RS
as well as Fly Bikes front hubs.
ID: 15mm
OD: 24mm
Special size: No

Primo Mix/Remix and N4 FL front hub shell bearing – 6902 2RS
ID: 15mm
OD: 28mm
Special size: No

Primo Freemix:
Driver Bearing: 6802 2RS
ID: 15mm
OD: 24mm
Special size: No

Primo Freemix Hub Drive Side Bearing:
7905 2 RS
ID: 25mm
OD: 42mm
Special size: no

Primo Freemix Hub Non Drive Side Bearing:
6202 2 RS
ID: 15mm
OD: 35mm
Special size: No

Profile rear Hub shell Bearing – 6903 2RS
ID: 17mm
OD: 30mm
Special size: No

KHE Hub Shell Bearing – 7905 2RS
ID: 25mm
OD: 42mm
Width: 9mm
Special size: No

Odyssey Vandero Bearing – 16287
ID: 15mm
OD: 26mm
Special size: Unknown

United, Giant rear hub shell bearing – 15267 2RS
ID: 15mm
OD: 26mm
Special size: unknown

* Special Size i.e Not available in bearing shops

United LRD Hub | BMX Direct LRD Hub | Bicycle Union LRD Hub
Shell Bearings: 2x 6902 2RS
Driver Bearing: TBA

United SU3 Front hub bearing
15267-2RS
15x26x7mm

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“What’s the difference between the 19mm Primo mid BB and the Spanish BB?”

The main difference between the 2 types is the outer diameter of the bearing.
The ‘Mid’ bearing is 41mm on the outside and a ‘Spanish’ BB is 37mm.
So depending on the frame you have you should choose the correct option.

**Last up dated June 2024