BMX Bottom Bracket Buyer’s Guide
The bottom bracket, commonly referred to as the “BB,” is located inside the portion of a frame that the crankset’s spindle passes through. It’s essentially a set of bearings that is tucked away inside the frame, and it allows the cranks to spin freely. Because BMX riding is done almost entirely from a standing position, with most of your weight on the pedals, all big landings put a significant amount of stress on your bottom bracket. The bearings are the most important part of the bottom bracket and high quality ones will be able to take huge amounts of abuse while remaining lightweight.
Types and Sizes
Basic bottom brackets will have loose-packed ball bearings and more expensive ones will use a sealed bearing system. Sealed bearings provide increased strength and durability.
There are several variations of bottom brackets that use different bearing styles. These can be broken down into four groups: American, Mid, Spanish, and Euro.
American Bottom Brackets – American bottom brackets were more common in the early days of BMX. They use a bearing set that rests inside cups that are then pressed into the frame. The downside to American bottom brackets is that they are large and contain unnecessary weight. They also take a considerable amount of force to press the cups into the frame. They are often found on bikes with one-piece cranks.
Mid Bottom Brackets – Mid bottom brackets use the same bearings that American bottom brackets use, however the cups are completely removed from the equation. The bearings are pressed directly into the frame, allowing for a less complicated setup and a reduced weight. Because the bearings are the same size as an American bottom bracket, there is no difference in strength between the two styles. This style of bottom bracket is the most common.
Spanish Bottom Brackets – Spanish bottom brackets also use bearings that press directly into the frame. Spanish bottom brackets use a bearing with a smaller diameter than a Mid bottom bracket, which means a smaller bottom bracket shell and less weight.
European Bottom Brackets – European bottom brackets are only common to race frames. European bottom brackets use smaller bearings that sit inside a cup that is threaded directly into the frame.
There are also two different spindle sizes that bottom brackets can accept. These are 19 and 22mm.
Materials
Bottom bracket bearings and cups are generally made from stainless steel. The hardware and spacers are usually made from aluminum.
Things To Look For
Bottom brackets are subject to some pretty serious abuse. When choosing one, it is important to consider the kind of riding you do and how harsh it is on your bike. If you ride street, you should prioritize strength. If you perform more technical park tricks or race, it may be more important to have the lightest bottom bracket possible. Either way, when choosing this component it is a good idea to think about the type of wear and tear your riding style entails.
How Much To Spend
Bottom brackets range in price from $15 to $60. Because they are all so similar in design, paying more for a bottom bracket means you’ll likely get higher quality bearings. Almost all aftermarket bottom brackets over $15 use sealed bearings. The more expensive versions will use more precise bearings that spin better and last longer. Also, depending on your crankset, you may be required to purchase a more expensive bottom bracket designed specifically for your cranks.
Product Reviews
Before buying, be sure to do your research and read product reviews. Reviews are a great way to find out specifics about a particular model, user impressions, and things to watch out for. After you’ve purchased a product and had enough time to thoroughly test it, we encourage you to leave a review for other people to see when they are researching bikes and parts on the web.
We hope you’ve found this information to be helpful. If you have a question that isn’t answered in this guide, our BMX forums are a great place to get advice from knowledgeable riders. Your local bike shop is also a great resource.
