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BMX Bike Sizing
Choosing the right size BMX Bike!
A lot of people look at BMX as being a simplistic bike; just a BMX. Most of the people couldn’t tell you the difference between department store disaster and a purpose-built machine, but we know better! We know the kind of engineering and design that goes into making a BMX capable of the handling punishment we dish out. Basically, we know not all BMXs are created equal.
Size Does Matter - Wheels & Top Tubes
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, ranging from 12” inch, 14" inch, 16" inch, 18" inch, 20" inch & 24” inch.
- 20” Wheels are the most common and are the true size for BMX
- The Top Tube (TT) measurement is the most important measurement when considering a new bike. This is more important than wheel size.
- Most BMX Bikes with 12” – 18” wheels, and 24” cruisers have relevant TT lengths to their size wheel.
- 20” inch Wheel'd complete BMX bikes 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:
|
Height / Discipline |
Freestyle |
Race |
|
Under 100cm (Under 3’3”) |
12” Wheel Size Balance or Pedal (Based on confidence) |
12” Balance* Class Size |
|
99cm – 122cm (3’3” to 4’) |
Micro Mini* Class Size |
|
|
122cm - 137cm (4’ to 4’6”) |
Mini Class Size |
|
|
137cm – 147cm 4’6”-4’10” |
(Small Top Tube size) |
Junior Class Size |
|
142cm – 177cm 4’8”-5’4” |
19.5” – 20.4” Top Tube Length |
Expert Class Size |
|
162cm – 178cm 5’4”-5’10” |
20.25” - 21” Top Tube Length |
Pro Class Size |
|
172cm – 180cm 5’8”-6ft |
20.5”-21.5” Top Tube Length |
Pro XL Class Size |
|
180cm + 6ft + |
21” - 22” Top Tube Length |
Pro XXL Class Size |
FREE Coaching Clinic with every Complete BMX Bike Purchased at RampFest
At RampFest, we run BMX Lessons for First Timers to Advanced riders - so let's get started today.
Best Bike for your Riding Style
Next to consider is what kind of riding will you be doing:
- Park – Most park (skate park) riders prefer a more responsive bike. This can be achieved by a shorter Top Tube, Shorter Chain Stay (CS) and steeper Head Tube (HT) angle. When referring to the above chart, you’ll be looking at the shorter end of this scale - such as bikes with a 20" - 20.8" inch top tube. A great example is the Forgotten Lurker, WTP Nova or the Cult Getaway
- Trails – Trail/Dirt riders typically prefer something bigger and more stable. This can be achieved with a longer TT, CS and a slacker HT angle. This makes for a more stable and comfortable ride when jumping larger jumps. Trails riders would want a Top Tube about 21" inches - such as the Forgotten Damned
- Street– Street riders sway between either end of this scale and will normally sit somewhere in the middle, depending on their personal preference. Street BMXs are generally built a bit tougher as well to take grinding abuse and flat landings better. A great example is the WTP Arcade
Most complete bikes will sit somewhere in the middle, and will be fairly well setup to take on most things, with the exception of some higher end bikes which are clearly orientated towards a more specific discipline.
Once you really get a feel for BMX, and know the exact sizing you want, you might want to try shopping for BMX Frames & Parts separately to build a custom BMX just for you.
BMX Bike Price Points
We all know that price is important, so let's have a look at some of the key differences you'll see.
We know that sizing is important, but when looking at BMX Bikes, what is the first thing you notice? Most of the time, it will be the price. But, what do you get for your money?
BMX Bikes Under $599
Bike will feature economical parts, Hi-Ten Steel frames, single-wall rims and Hi-Ten Steel parts. These bikes are for entry level guys that aren’t as likely to take BMX too far. Most sizes will be under 20.5”.
BMX Bikes $600 - $899
Now you’re starting to get 4130 Chromoly Main tubes and mostly sealed bearings. You will start seeing double wall rims, parts based on pro models and sizes will typically run between 20.4”-20.8” top tubes.
BMX Bikes $899 +
Full 4130 Chromoly frame, fork and bar, some after-market parts and premium quality components. These bikes will normally size from 20.5”-21” top tubes.
BMX Bikes $1500 +
At this price point, there aren't many Complete Bikes on the market - you're likely looking at building a custom Frame & Parts combo. Now you’re playing the real game. Full 4130 Chromoly parts and all after-market parts & accessories. Most of these bikes (if not all of it), you could pick off a shelf part for part. This is the big leagues and will be sized to suit.
What Are BMX Bikes Made From?
Hi-Ten Steel: Hi-Ten or High Tensile Steel. Cost effective to manufacture, easy to work with and stronger than your average mild steel.
4130 Chromoly: Chromoly Steel is a mixture of Chromium and Molybendium to form the most popular steel available in BMX. This is lighter and stronger than Hi-Ten Steel.
-Heat Treating: On high-end bikes, you may come across “heat treated” steel. What this is, is a special process of heating and cooling the steel, after welding to increase the strength of the Cro-Mo steel tubing.
Typically, you can make a fair judgement on what the quality material is being used, based on the price range.
Shop BMX at RampFest
Complete BMX Bikes from $459, plus full range of BMX Parts & Accessories available now...
The Extra Details - Part Sizing
For those of you who may be looking to build a custom bike up or are just looking to dial in your ride a little further and aren't too sure on the ins & outs of how part angling & length can influence the " feel " of a bike by something as minute as millimetres.
Crank Arm Lengths
Crank Arm length effects how far apart your feet will sit when you ride. A 175mm crank is fairly standard and gives a smooth & stable ride as your feet are spaced slightly further apart therefore creating a wider balance point. Where as " New School " street or technical park style riders are opting to run a 10mm shorter, 165mm crank. This brings your feet slightly nearer together & can create a more responsive & " poppy " feel & can also help those running four pegs avoid hitting their rear foot.
Fork Offset
This is the distance your dropouts sit out from your main fork tubing, and plays a roll in how your front end feels when manoeuvring your bike. A slightly more laid back offset of 30mm or higher can give transition riders the stability they need to pull back when airing a quarter pipe or jumping a box jump. However a street rider may want a quick and responsive front end for technical front wheel balance moves like nose manuals & poppy low to the ground spins an offset of 28mm or even as steep as 20mm may be more desirable.
Handlebar Width & Rise
BMX Handlebars come in a wide range of shapes & sizes which seems to be progressively becoming larger as time goes by. This has however made riding BMX bikes much easier & manoeuvrable in comparison to what they once were. Bar sizing much like frame sizing can come down to your height & body type or as simple as personal preference. Most brands tend to run Rise sizing from 9" & up by various increments with this meaning the height of your bars from stem clamp to the peak of the handlebar height. Bar Width can for some enable a feeling of more control with the extra inches either side and give a wider more balanced centre of gravity when riding & pulling off of transitions or even flat ground. Most bars on the market come at a width between 28.5" - 30" nowadays & it is entirely up to your discretion as to what and how you run them. Some prefer smaller bars to keep their knees clear when performing bar spins & other tricks where as others may feel they are a fan of a wider set for a more balanced ride.
Bearings
Unsealed Bearings: These are loose bearings or bearings in a cage that sit in a purpose-made race. Under abuse, these may need to be tensioned and maintained. For a basic bike, these are fine, however, they will not be as good as sealed bearings.
Sealed Bearings: Sealed bearings means that a sealed cartridge bearing is being used. In BMX these typically mean they are higher quality, will take more abuse, have less maintenance, and generally last a lot longer than Unsealed bearings. This is something you should look for in any high-quality complete.
Semi-Sealed: A mixture of sealed and unsealed bearings. Normally this will relate to the rear wheel.
Wheels
Single Wall Rims: Refers to the inner wall of the rim itself. Single wall rims are your standard rim, with only one horizontal wall. If it doesn’t say double wall, you can be safe to assume it is a single wall.
Double Wall Rims:This means you have two horizontal walls in your rim, which, means more strength. The shapes in which these walls and ribs run can vary, but if it says double wall, you can expect it to be much higher quality than a single wall rim.
Got a Question? Get in touch and let us help
Now you should have everything you need to get the right bike, right size and right price!
You can always give us a call or drop into the store and check out the range of bikes we have available.
The most important thing to consider when buying your new bike is: The one you like most, is the one you will ride most!
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