How to choose your road bike bottom bracket?

How to choose your road bike bottom bracket?

Ensuring the best possible smoothness of ride for your cranksetthis part must comply with the frame and crankset standards. Between frame and crankset standards, a little help is welcome!

Standards

  • Bearing type: steel or ceramic
  • Crankset axle type: Hollowtech II, GXP, BB30, etc.
  • Type of bottom bracket on frame: BSC, BB30, etc.

Bottom bracket types

Let's start with the simplest: the bearing quality. Generally speaking, you'll find the same housing with bearing steel or ceramic. The ceramic used for bicycle bearings has a harder, unalterable surface than steel. The advantages are a low coefficient of friction and longer, maintenance-free service life. However, this only applies to 100% ceramic bearings, i.e. both the balls and the rings.

For compatibility withcrankset axlethings start to get tricky. Different brands have different standards. To help you identify what you need, here's a list of the most common:

  • Hollowtech II, Megaexo: 24 mm diameter axle
  • GXP: 22 mm diameter shaft on the left, 24 mm on the right
  • Power-Torque: 1-piece 25 mm-diameter axle
  • Ultra-torque: 2-piece axle, 25 mm diameter
  • BB30: 30 mm diameter axle

    As if the standard bottom-bracket axle wasn't enough, you'll also need to match the gearbox to the axle. frame standard. Here's another guide to the most common ones:

    • BSC (also known as BSA): internal frame diameter 34.8 mm
    • Press-Fit: internal frame diameter 41 mm
    • Press-Fit30: internal frame diameter 46 mm
    • BB30: frame internal diameter 42 mm

      Please note that some road frames are equipped with a extended bottom bracket for a specific crankset, such as the 386EVO system, which is an extended BB30.

      Which bottom bracket should I choose?

      When it comes to replacing bottom brackets, you won't necessarily have a choice apart from bearing quality. Your choice will depend on the standard of your frame and the axle of your bottom bracket.

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