BMX Bottom Brackets are all the same, aren't they?

Author: Tim   Date Posted:29 January 2020 

Bottom Bracket Buyers Guide


Buying a bottom bracket should be straight forward since the majority of BMX bikes come with a standardized size of tubing to fit the bearing snug. However, with the number of bottom brackets on the market, this process can become overwhelming to the untrained eye. The bottom bracket allows the rider to spin the cranks freely while pedaling, having a correct running bottom bracket is important as it’s the core of your BMX bike. The bottom bracket is made up of 2 individual bearing rings and a center spacer piece. This is accompanied by the spacers and shims to ensure the bottom bracket holds the cranks in place correctly. 


Size /Style  

Bottom brackets come in two main designs Loose ball and Sealed ball bearing. Since this is an article aimed at buying bearings for your BMX in 2020 we will leave the loose ball bearings here. Now we have that established the next thing to decide is what type of bearing you’ll need. BMX frames are made in a variety of sizes and shapes and the tubing where the bottom bracket fits is no different. Bottom brackets for BMX bikes come in 19mm, 19mm mid, 22mm, 22mm mid, and 24mm. Basically, this size refers to the size of the spindle that will pass through the bearing and allows the cranks to spin. This size of your bearing will be depending on the brand of your cranks as some brands will make a specific size only. The next size to take note of is the size of the bearing case itself and this is determined by the frame style you own.  Bottom brackets come in a range of styles including Mid, Euro, USA, and Spanish.   


Finally, bottom brackets come in both Internal and External bottom bracket options. Internal bearing are more common in freestyle BMX where some riders opting for the external style. The classification of the bottom bracket is important as it dictates the type of bearing that will fit your frame. Make sure to check with your local store before buying your bottom bracket to make sure you get the right one for your ride. 


Since Bottom brackets are made in a similar machine process, the result is the good majority of bottom brackets weighing very similar between 170-200gms.  The weight of the bearing won’t vary much from brand to brand and is only changed by the spacer and materials used to make these spacers and washers. Some brands use a steel washer which is naturally heavier then Alloy washers and spacers, over the year’s certain brands have tried to replace the spacers with plastic or other lighter materials. For the weight-conscious BMX riders, the bottom bracket doesn’t offer much when it comes to shaving weight.   


Colour & Brand

Since the functional component of your bottom bracket is made by a third party it leaves brands only able to change the colors and spacer designs that we have seen over the years. Bottom brackets come in an array of colors, tones, and textures, with many brands offering something new to keep it customizable. Most Brands in BMX make a bottom bracket since it’s such a simple piece so riders are spoiled for choice when it comes to picking out the best bet bottom bracket for you.



Even though Bottom brackets come in a variety of styles and sizes they don’t vary in price much with the main difference being between internal and external bottom bracket styles. Cheaper bottom brackets start in the $30-$40 range, where the upper end of the scale could see you paying $100-$110 for an external Bottom Bracket.