Bottom brackets may be a bike’s least appreciated component, but they play a huge role in energy transfer and efficiency. Without bottom brackets, a simple exercise like pedaling would be impossible. To appreciate and understand the role of the bottom bracket, we shall take a look at the numerous standards available to ICAN consumers.

What is a Bottom Bracket?

The bottom bracket is the machine that allows free rotation of the bike’s crankset. The bottom bracket fits in the bottom bracket shell; which found where the seat tube, the down tube, and chain stays attach. Bottom brackets have different configurations; this is what sets one type of bottom bracket from the other.

Bottom brackets are not universal, some brackets are specific to certain frames. As you shall find in the article, the compatibility of the cranks is also limited to specific types of cranksets.

The Main Types of Bottom Brackets Available in the Market

There are many configurations of bottom brackets that comply with different standards around the world. Bottom bracket types differ in shell width, spindle length, and threading. There was a time when Bottom bracket standards were fewer’ key decisions and differences revolved around the spindle dimensions, type of threading, and shell width. These days, there are as many bracket standards as there are bicycle brands. In this article, we shall concentrate on the BB model which has six different variants of bottom brackets.

Below is a list of BB model bottom bracket options that are available to ICAN consumers;

•    BSA
•    BB92
•    PF30
•    BB30
•    BB86
•    BB386

Ⅰ. BSA Bottom Brackets

BSA bottom brackets are of the treaded variety; they feature threads on both sides of the shell. BSA bottom brackets are predominantly common among bikes manufactured before 2010. Pre 2010 bikes typically featured BSA bottom bracket shells. With a BSA bottom bracket, you have an option of four widths; 68mm, 73mm, 83mm, and 100mm.

A 68mm wide bottom bracket is used in road bikes while mountain bikes are fond of the 73mm wide bottom bracket. The 83mm and the 100mm wide bottom brackets are quite rare these days.

How can you identify a BSA bottom bracket? A bearing description of 1.37x24 distinguishes a BSA bottom bracket (as in the image below).

A BSA bottom bracket

The BSA bottom bracket is compatible with the following cranksets;

1. Square axle
2. ISIS
3. Octalink
4. Shimano Hollowtech II
5. SRAM GXP
6. BB30
7. FSA Megaexo
8. BB386EVO
9. Rotor 3D+
10. Campagnolo Ultra Torque
11. Campagnolo Power Torque

Ⅱ. BB30 Bottom Bracket

Since 2006, BB30 brackets have been a popular option among bikes. The BB30 gets its name from its 30mm internal diameter which ensures low weight and high stiffness. BB30 bottom brackets come in two variants; 68mm and 73mm widths. Sixty-eight-millimeter brackets are used in road bikes while 73mm wide bottom brackets are used in mountain bikes. Some mountain bikes also use 73mm wide bottom brackets.

 You can identify a BB30 bottom bracket by its 42mm external diameter and the fact that the bearing shells are not visible. BB30 bottom brackets do not have bracket shells, so the bearings have direct contact with the frame.

 BB30 bottom brackets are compatible with the following cranksets;

1.    Shimano Hollowtech II
2.    Rotor 3D+
3.    SRAM GXP
4.    BB30 crankset
5.    FSA MegaExo
6.    BB386EVO
7.  Campagnolo Ultra Torque and Power Torque cranksets

Ⅲ. BB86 Bottom Bracket

The BB86 bottom bracket is a Press Fit bracket with its bearings concealed by an aluminum or plastic bracket shell. The bracket shells reduce wear and tear. BB86 bottom brackets are used in both mountain bikes and road bikes.

The BB86 bottom brackets are compatible with the following cranksets;

1. Shimano Hollowtech II cranksets
2. Rotor 3D+
3. SRAM GXP
4. BB30
5. FSA MegaExo
6. BB386EVO crankset
7. Campagnolo Ultra Torque and Campagnolo Power Torque crankset

  Ⅳ. PF30 Bottom Bracket

Similar to the BB86, the PF30 is a Press Fit bottom bracket. The PF30 has an internal diameter of 30mm and an external diameter 46mm which allows the fitting of a plastic shell. The PF30 shares certain similarities with the BB30 bracket in that they share the same type of bearings. The PF30 is easier to install, compared to the BB30. Unlike the BB30, the creaking noises associated BB30 is eliminated. The 68mm wide PF30 is associated with road bikes while the 73mm variant is common among mountain bikes.

The PF30 is compatible with the following cranksets;

1.   Shimano Hollowtech II
2.    Rotor 3D+
3.    SRAM GXP
4.    BB30 cranksets
5.    FSA MegaExo
6.    BB386EVO crankset
7.    Campagnolo Ultra Torque and Power Torque cranksets

Ⅴ.  BB92 Bottom Bracket

Also known as the Shimano Press Fit, the BB92 has a 41mm external width that allows the installation of an aluminum or plastic bracket shell. The BB92 is designed with a 24mm spindle that is used by Shimano. The bracket shells cushion the bottom bracket’s bearings from contact with the frame. This cushioning greatly reduces wear and tear. This 92mm wide bottom bracket is common among mountain bikes.

The BB92 bottom bracket is compatible with the following cranksets;

1. Shimano Hollowtech II cranksets
2. Rotor 3D+
3. SRAM GXP
4. BB30
5. FSA MegaExo
6. BB386EVO crankset
7. Campagnolo Ultra Torque and Campagnolo Power Torque crankset

  Ⅵ. BB386EVO Bottom Bracket

Defined as “the best of both worlds,” the BB386EVO combines the stiffness of the 30mm spindle with that of the 86.5mm wide bottom bracket. The FSA developed the BB386EVO. The external characteristics of this 86.5mm wide bottom bracket allow for a narrow plastic edge. To identify the BB386EVO, check out for an FSA Standard Sticker on the frame.

The following cranksets are compatible with the BB386EVO bottom bracket;

1. Shimano Hollowtech II cranksets
2. Rotor 3D+
3. SRAM GXP
4. FSA MegaExo
5. BB386EVO crankset
6. Campagnolo Ultra Torque and Campagnolo Power Torque crankset