Carbon BMX Wheels - Shred Life and Enjoy The Ride!
BMX Bike, Wheel and Tire Sizes?
BMX Tire Sizes
In attempts to be more accurate, or maybe just more confusing, manufacturers of BMX wheels and tires use a few different scales for sizing. Here we will try to explain these some for you.
20" BMX wheels
This can be the most confusing segment of wheels to choose from. In wheel sizes that are all 20" you have a few different bead diameters available. These MUST match to the tire used.
406mm: The 406mm bead diameter bmx rims work with the decimal based tire sizes such as 20x1.50 - 20x2.0. These are common with Pro size riders (we will get to that below on bike sizing).
451mm: The 451mm bead diameter bmx rims work with fractional tire sizes such as 20x1 1/8, 20x1 3/8 and so on.
OS20 451mm: OS20 is a fairly new bmx rim sizing that features a 451mm bead diameter in a wider width. These rims use ONLY OS20 tires. Overall the OS20 wheel is larger than the 20x2.125 but is still “20 inch” within the UCI guidelines. The OS20 rims are 451 diameter (a regular 20” is 406), which is the same diameter as a 20x1 3/8” rim. There are only a couple of tire options currently available.
Cruiser 24": Even the 24" cruiser wheel now has different rim diameters. In 24" we find the 507mm bead diameter for Pro and Expert sizes (24x1.5-24x2.0 and 24x1 3/8). We then have the 520mm rim that works with you 24x1 1/8 tire.
BMX Bike Sizes
What Size BMX Race BIke?
Equally difficult are all the bike sizes used (which correspond to racing experience classes but do not indicate you must race this size.) Below is a break down on BMX bike frame sizes to help you find the right fit for your rider.
The image to the right shows the various dimensions a rider needs to be familiar with when choosing a bike.
BMX Frame Geometry:
C: Arguably the most critical dimension is the top tube or reach.
G: Stand over height makes sure you can stand over the bike and not fall over.
A: Head tube angle (HTA) impact steering sensitivity and stability
E: Chainstay length. This comes into play in rhythm sections, manuals and overall bike stability and length.
B: Seat tube angle
D: Seat Tube Height
WHEELS & TOP TUBES - Bike Frame Sizes
First things first, size does matter! However, it’s not a matter of bigger is better so let us explain:
- BMX Bikes come in multiple wheel sizes that we discussed above.
- 20” Wheels are the most common size for BMX racing
- The Top Tube (TT) measurement is the most important measurement when considering a new bike. This is more important than wheel size.
- 20” bike models and brands can feature different size TTs.
The Top Tube (TT) is the top tube on a BMX bike frame that connects the front of the bike (HT) and the seat post tube (ST). Like any bike, there are different sizes to suit different size riders. Here is an approximate guide to BMX Bike Sizing:
- Under 3'3" (100cm): 12" balance bike
- 3'3" to 4' (99cm–122cm): Micro Mini - 20 x 1 1/8
- 4' to 4'6" (122-137 cm): Mini - 20x1 1/8
- 4'6" to 4'10" (137-147 cm): Junior - 20x 1 1/8
- 4'8" to 5'4" (142-162 cm): Expert - 20x1 3/8
- 4'8" to 5' 9" (142-175 cm): Expert XL (Some MFG Only) - 20x1.50
- 5'4" to 5'10" (162-178 cm): Pro - 20x1.50-2.0
- 5'9" to 6' (178 cm- 182 cm): Pro XL - 20x1.50-2.0
- 6' and UP: Pro XXL - 20x1.50-2.0
Of course all of these measurements are "suggestions only" and a rider needs to find the size they are most comfortable with. Many aggressive riders may find a smaller size fits their style better. Those seeking more stability may opt a little larger.
