Welcome to our comprehensive guide on press fit bottom bracket types and sizes. Whether you’re upgrading your crankset or simply replacing a worn-out bottom bracket, it’s crucial to know the specific type and size currently fitted on your bike, as well as the compatible options available. In this article, we’ll provide you with valuable insights and practical knowledge to help you better understand the differences between press fit bottom brackets, enabling you to make the right decision when buying and fitting a replacement.
A press fit bottom bracket is a type of bottom bracket that does not screw into the bike frame like traditional threaded bottom brackets. Instead, the bearings, or the bearing cups, are pressed directly into the frame. This creates a secure and tight fit that eliminates the need for threads. This design allows for a larger diameter axle and increased stiffness in the bottom bracket area.
Advantages of press fit bottom bracket
- They are lighter than threaded bottom brackets.
- They offer better power transfer. Press fit bottom brackets can allow for larger diameter spindle and bearing sizes. This can increase the stiffness and power transfer of the bottom bracket.
- Different Standards of Press Fit Bottom Bracket
Companies like Cannondale, Shimano, Sram, Trek, FSA or Cervelo have introduced several different standards of press fit bottom brackets, each with its own unique design and compatibility requirements. Some standards are proprietary to specific bike manufacturers, while others are more widely adopted.
Press fit bottom bracket sizes for direct fit
Some push fit bottom brackets are designed as a set of sealed bearings that are pushed directly into the bottom bracket shell. The bearings are usually kept in place by the retaining clips fitted in the grooves in the bottom bracket shell.
retaining clip on press fit bottom bracket direct fit standards
The retaining clip used in press-fit bottom bracket shells is a small metal clip that is designed to prevent the bearings from moving or shifting inside the bottom bracket shell. It is also known as a circlip or snap ring.
A BB30 bottom bracket is a type of press-fit bottom bracket system that was introduced in 2000 by Cannondale. It has since become a widely used standard in the cycling industry.
BB30 bottom brackets use a 30mm diameter spindle and oversized bottom bracket shell (BB shell). The shell has an inner diameter of 42mm and a width of 68mm (for road bikes ) and 73mm (for MTB). The bearings sit directly inside the BB shell.
BB90 and BB95
They are two press-fit bottom bracket standards developed by Trek, a well-known bicycle manufacturer, and used on their bike frames. The bearings are press fitted directly into the bottom bracket shell.
BB90 and BB95 both refer to the inner diameter of the bottom bracket shell on the bike frame. The BB90 standard found on Trek’s road bikes has a shell width of 90mm. The BB95 standard found on Trek’s mountain bikes has a shell width of 95mm.
They are designed to accommodate 24mm spindles
This stands for Oversized Bottom Bracket, and it is a standard developed by Specialized Bicycles. The OSBB system was designed to provide a narrower bottom bracket shell on their carbon road bikes. with the goal of reducing the q-factor. It is essentially a specialized equivalent of the BB30 standard.
BBRight (Direct fit)
A type of press-fit bottom bracket system that was developed by Cervelo, a Canadian bicycle manufacturer. It is designed to provide a wide, stiff, and efficient platform for high-performance road and triathlon bikes. BBright bottom brackets (direct fit) use a shell width of 79mm and an inner diameter of 42mm. It accommodates 30mm cranksets.
BBright bottom brackets are characterised by their asymmetrical design, with a larger non-drive side and a smaller drive side. This design helps to balance the forces generated by pedaling and maintain a good chainline. This can improve shifting performance and reduce wear on the drivetrain.
Press fit bottom bracket sizes for bearings in the cups
Another design incorporates cups that the bearings are pressed into, and are then pushed into the bottom bracket shell. They also come with sleeves that protect the bearings from water and dirt that can get into the frame. They require a wider inner-diameter bottom bracket shell to accommodate the cups.
A type of press-fit bottom bracket system that was introduced as an extension of the BB30 system. PF30 stands for Press Fit 30, which refers to the way the bottom bracket bearings are installed in the frame.
Like BB30 bottom brackets, PF30 bottom brackets use a 30mm diameter spindle. However, they require an oversized bottom bracket shell with an inner diameter of 46mm.
PF 30 uses a width of 68, 73,83, and 100mm.
PF30 bottom brackets differ from BB30 in that they use pressed-in bearing cups rather than direct-fit bearings. The pressed-in cups help to maintain the alignment of the bearings and prevent creaking. This can be a common issue with BB30 bottom brackets.
This is a Specialized equivalent of the PF30 bottom bracket.
A BB86 bottom bracket is a type of press-fit bottom bracket system that was developed by Shimano. It is also known as Press Fit 86, BB86-92, or PF86.
BB86 bottom brackets use a shell width of 86.5mm and an inner diameter of 41mm. They are designed to accommodate 24mm diameter spindles.
A BB92 bottom bracket is a type of press-fit bottom bracket system that was also introduced by Shimano. It is also known as Press Fit 92 or PF92.
BB92 bottom brackets use a shell width of 92mm and an inner diameter of 41mm. They are designed to accommodate 24mm diameter spindles.
A type of press-fit bottom bracket system that was developed by FSA (Full Speed Ahead). It is also known as Press Fit 386.
BB386 bottom brackets use a shell width of 86.5mm and an inner diameter of 46mm. They are designed to accommodate 30mm diameter spindles.
BBRight (Bearings in the cups)
These bottom brackets use a shell width of 79mm and an inner diameter of 46mm (to accommodate bearing cups). The bottom bracket is designed to accommodate 30mm diameter spindles. The bearings sit in the cups that are pressed in the bottom bracket shell.
A type of press-fit bottom bracket system developed by SRAM for use with their DUB (Durable Unified Bottom bracket) cranks. It is designed to provide a lightweight, durable, and efficient platform for mountain bikes.
Sram offers 4 bottom bracket options that are compatible with the most press fit standards.
DUB bottom brackets use a shell width of 68mm, 73mm, 83mm, 89.5mm, 92mm 100mm, 104.5mm, 107mm, and 121mm. They use a shell inner diameter of 41mm, 42mm, and 46mm and they are designed to accommodate 29mm diameter DUB spindles.
Choosing the correct replacement for your specific bike and bottom bracket standard is essential to ensure proper compatibility.
Common press fit bottom bracket sizes and standards
|BB Standard||BB shell internal diameter||BB shell width||Crank spindle diameter||Direct fit/ Bearing in the cup|
|OSBB Road||42mm||68mm||30mm||Direct fit|
|BBRight Direct fit||42mm||79mm||30mm||Direct fit|
|PF30||46mm||68mm/73mm/83mm/100mm||30||Bearing in the cup|
|OSBB MTB||46mm||61mm||30||Bearing in the cup|
|BB86||41mm||86mm||24mm||Bearing in the cup|
|BB92||41mm||92mm||24mm||Bearing in the cup|
|BB386||46mm||86.5mm||30mm||Bearing in the cup|
|BBRight Bearing in the cup||46mm||79mm||30mm||Bearing in the cup|
|29mm||bearing in the cup|
If you have found value in our article and it has brought you knowledge, or a fresh perspective, we would be grateful for your support. By sharing our articles with others, you help us reach a wider audience and spread the ideas we believe in. Your voice carries weight, and together, we can make a difference.
Additionally, we invite you to consider becoming our patron. By contributing to our creative endeavours, you enable us to continue producing high-quality content, explore new topics, and enhance the overall experience for our readers. Your patronage allows us to thrive and create even more engaging and inspiring content for you to enjoy.