Why Do BMX Bikes Have Small Cranks?

Cranks or sprockets are a vital part of BMX bikes. With the right crank, you will become more efficient than an ordinary belt driver, and it will protect you against creep or sleep. Furthermore, cranks are more compact than belt drivers and tend to operate effectively at high temperatures.

However, cranks differ significantly in sizes and material, which has left most individuals wondering why BMX bikes have small cranks.

Some BMX riders swear by bigger cranks, while others claim that small cranks are the best. But which one is overall the best? To find out about this, consider reading this article to the end.

Why Do BMX Bikes Have Small Cranks?

Usually, BMX bikes are designed for different applications from street riding to dirt jumping and racing; as such, the size of sprockets will differ significantly depending on the desired application.

In addition to that, limitation in gear ratios and rear hub shell design and brake mount position plays a significant role in sprocket size. As a result, the best crank size will be determined by the intended purpose of your BMX bike against the functional gear ratio, brake mount placement, along with the size of the rare cog.

However, why does the BMX bike have small cranks? Small cranks or sprockets are used in BMX bikes to offer more contact surfaces.

Unlike big cranks, the small cranks tend to bend less easily, which results in leverage force on the crank. In addition to that, small cranks are relatively easy to prevent from contacting any inert objects when performing tricks.

This, in turn, results in less damage than the bigger sprockets. Lastly, small cranks are relatively light in weight, unlike their counterpart, the larger sprockets.

This is a vital aspect since weight is of major concern in any operator of a human-powered and a BMX bike is no different. A lighter ride often leads to less effort from the cyclist.

Does Size Of A Crank In A BMX Bike Matter?

Does size of a BMX bike crank really matter? This is a vital answer that needs to be answered, especially if you are new to BMX biking. Usually, big wattage and great power are often what most BMX bikers seek, and one way to achieve it is through improving the biomechanical connection of your BMX bike.

Since biking is all about pedaling, the best way to optimize your BMX bike is via the crank length. This means that crank size does matter when it comes to optimizing the performance of your BMX bike.

However, which one is better, the small or big sprocket? Since length is vital when it comes to enhancing the performance of your BMX bike, understanding which size is best for you is vital. Usually, the bigger the crank, the lesser the effort it exerts on the chain.

This means that a BMX bike equipped with a significantly large crank will face fewer broken or damaged chains, unlike its counterpart, the small crank.

In addition to that, big crank teeth tend to contact chain surfaces less often and wear for an extended period than small cranks. However, the downside of using big cranks is that they are relatively heavy due to the extra material used in their construction.

Unlike big cranks, small cranks are relatively light in weight and easy to protect against contacting inert objects as you perform tricks. However, unlike the big cranks, small cranks tend to bend easily; this means they are not ideal for performing stunts that put more abuse on the bike, such as massive drops.

What Size Of BMX Bike Cranks Should I Use?

When looking for a BMX crank, understanding the size that will best suit your needs is crucial. However, answering the question of what size of BMX crank I should use can be tricky. Not only do BMX bike sprockets come in different lengths, but also come in three unique spindle sizes; 24mm, 22mm, and 19mm.

BMX bikes have evolved significantly, and this means that their products have also been refined over the years to get to the point they are nowadays. The quality of these bikes has reached a level that has made them trustworthy.

The question of what size of BMX crank should I use? has probably been in every BMX cyclist enthusiast. Therefore, to answer this question, we have put together a crank size guide to help you find what will best suit your needs. With that said, here are the vital aspect to note when choosing the right BMX bike crank to use;

Crank Arm Length

When it comes to BMX bikes, crank arm length is more of a preference. Nowadays, most riders use 175mm or 170mm size; however, you might consider going longer or shorter. Shorter sizes are often ideal for flatland and street riding, while longer sizes are ideal for racing and jumping. Therefore, 175mm and 170mm are ideal for park, dirt, and street riding.

Usually, length is often determined by your preference as a rider. Some riders prefer shorter cranks claiming that they are a deal for performing tricks and offer them foot clearance for pegs.

On the other hand, riders who prefer longer cranks claim that they offer more power when balancing or cranking. Most BMX bike cranks come in the size of 175mm and 170mm. Nonetheless, profile racing, for instance, features lots of sizes for each rider out there.

Spindle Size

For spindle size, there are three options to choose from; 24mm, 22mm, and 19mm. Size is often determined by the rider and the amount you put on the cranks.

The 19mm spindle size is ideal for BMX bikers who ride primarily on trails or ramps, and you have to be a smooth rider, as well as you should not be doing any big drops to rough or flat landing more often. These cranks are also ideal for street riding.

On the other hand, the 22mm spindle size provides the crank with extra strength making them significantly harder to bend. This spindle size is best for use among all-around cyclists that love the park, street as well as dirt riding.

The 22mm spindle size is capable of holding up to drops, grinds, and almost everything a rider does with their bike. Over the past few years, this spindle size has grown in popularity due to its top-notch strength quality; this is not a surprise compared to how wild cycling has become these days.

Finally, the 24mm spindle is another popular spindle size available in the market. These spindle sizes have been designed for street riders who tend to be significantly heavy on their cranks and often perform heavy drops, and tend to abuse their bike.

Since this spindle has a significantly large diameter, it becomes hard to bend or become damaged. These spindle sizes are heavy-duty; as a result, they are capable of withstanding anything a rider can do on their bike. However, as the spindle size goes up, weight also adds up because of the extra material used.

The Size Of The Bottom Bracket

When it comes to choosing the right crank size for your BMX bike, this is undoubtedly the easiest part. If you are not familiar with the bottom bracket, this is a part of a BMX bike frame where crank bearing presses in to allow the crank and spindle to rotate.

Since the standard size of a BMX bike frame nowadays features a Mid style bottom bracket, you might consider using 24mm, 22mm, or 19mm cranks providing you change the bottom bracket bearing and match it with your spindle size.

Therefore, to summarize what size of BMX crank I should use, it will depend on your preference as a rider a long with the type of riding style you are into.

As a street rider who does lots of drops and big grinds, you should consider going for a 24mm crank along with a shorter arm that ranges around 165 to 170mm.

On the other hand, if you are into ramp along with trails, you should consider going for a 19mm crank with a slightly longer arm within the range of 175 to 180mm. 22mm size with an arm length range of around 170 to 175mm is ideal for a rider who is into everything and loves sending some big stuff.

With these aspects in mind, finding a BMX bike crank that will best suit your needs becomes pretty much straightforward.

Final Verdict

Cranks are an undoubtedly vital part of a BMX bike; it aids in converting the power being produced by your legs into a rotational motion and drives your bike forward. Since they tend to come in an array of sizes, choosing one that will best suit your needs is crucial. Given the fact that cranks are levers, the longer they are, the more they amplify the effect of the given input force.

When it comes to choosing a crank for your BMX bike, this will highly depend on your preference, along with the type of riding style you use. After going through this article and understanding it, choosing the right crank for your bike becomes much easier. With that said, we hope that you have found this article beneficial and that your question on why do BMX bikes have small cranks has been answered accordingly.

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