FSA Platinum Pro MegaQuad ISIS Drive Bottom Bracket 68 x 108

FSA Platinum Pro MegaQuad ISIS Drive Bottom Bracket 68 x 108

Dependable bottom bracket for use with ISIS Drive splined cranksets. A forged hollow chromoly spindle gives stiffness for optimum power transfer, with integrated ball bearings giving the largest possible bearing dimension. New improved external seals prevent dirt and water ingress.

• ISIS Drive 68x108mm BB-9924CM (w/ Bolts)
• All-Purpose - strong and stiff
• Forged hollow Chromoly steel spindle for ISIS Drive
• Integrated large ball bearing design
• Cold forged aluminum cups
• Composite anti-creak sleeve
• New improved external water seals
• Light Stiff
• Cold Forged Aluminum cups
• Composite anti-creek sleeve
• Titanium Nitride coated Spindle

Determining the Correct Bottom-Bracket Size for Your Bike Frame

When it comes to choosing the right bottom bracket for your bike, two key measurements need to be spot-on: the Shell Width and the Spindle Length.

1. Identify the Shell Width

The Shell Width is the first number you'll encounter in bottom-bracket sizing, such as the "70" in a 70 x 113 measurement. This number needs to align exactly with your frame's bottom-bracket shell width. To find this measurement, simply measure the width of the bottom-bracket shell on your bike's frame.

2. Determine the Spindle Length

The Spindle Length is equally important, represented by the second number in the sizing (for instance, the "113" in 70 x 113). This number must be compatible with your crankset.

• • Triple-Chainring vs. Double-Chainring: As a rule of thumb, triple-chainring cranksets tend to need a longer spindle length than double-chainring cranksets. The added chainring means more space is required between components.

3. Match the Threading Type

Ensure the bottom-bracket threading matches your frame. This is crucial as Italian-threaded and English-threaded bottom brackets are not interchangeable. Check your bike's specifications or consult a professional if you're unsure about your frame's threading type.

If you're still uncertain about the appropriate size or have specific questions, reaching out to a professional bike shop or contacting the bottom-bracket manufacturer directly can provide extra guidance. By ensuring these measurements and specifications align with your bike, you will maintain optimal performance and compatibility.

Understanding Bottom-Bracket Size Numbers

When deciphering the numbers in a bottom-bracket size, it’s essential to grasp their individual significance:

1. 1. Shell Width: This is the first number you’ll see, such as 68 in a 68 x 118 measurement. It denotes the width of the frame's bottom-bracket shell and needs to match the width specified for your bike frame.
   2. Spindle Length: The second number, like the 118 in our example, refers to the spindle length, also known as the axle. It's crucial for compatibility with your crankset. Typically, a triple-chainring crankset demands a longer spindle length compared to a double-chainring setup.
   3. Thread Compatibility: Additionally, ensure that the threading on your bottom bracket corresponds with your frame's threading — for instance, Italian-threaded and English-threaded bottom brackets are not interchangeable and must be matched correctly.

Each component plays a pivotal role in ensuring your bike's efficiency and function, making it vital to select the right sizes and threading.

When considering the interchangeability of Italian-threaded and English-threaded bottom brackets, the answer is a resounding no—these two types are not compatible with each other.

Here's why:

1. 1. Threading Differences: Italian-threaded bottom brackets have a distinctive threading pattern that is different from English-threaded ones. This means they are designed to fit specific bottom bracket shells on frames.
   2. Shell Dimensions: The dimensions of the bottom bracket shells also vary. Italian-threaded shells have a different width and thread diameter compared to English-threaded ones.
   3. Compatibility Issues: Attempting to install an Italian-threaded bottom bracket into a frame designed for English threading, or vice versa, will result in poor fit and potential damage.

For a seamless and secure fit, it's essential to match the threading of your bicycle frame with the correct bottom bracket threading—either Italian or English.