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Thread: Bottom Bracket

  1. #1
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    Bottom Bracket

    I am planning to replace the cranks on my hybrid and I decided to put road cranks. The specifications are:

    FSA Vero Square Taper Chainset Features:

    Cold forged AL6061/T6 crank arms
    Precision 100% CNC machined AL7075/T6 Outer Ring
    AL7075 stamped and CNC machined chainrings
    Heat treated chromoly inner chainring
    Chromoly chainring bolts
    Q-Factor - 143mm
    BCD - 130mm (39.53t) or 110mm (36.46t)
    Chainline - 43.5mm
    Compatible with JIS Square Taper BBs and power driver BB
    Recommended BB BB-7420 (103mm), BB-8420(108mm)
    Black Anodized or Silver Polished
    Laser graphics
    Weight: 699 g

    The problem is that they recommend 103 or 108mm BB. My current one is 121mm. How does this affect the drivetrain? Thanks.

  2. #2
    mtbr member
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    The different spindle length of the bottom brackets will give you different chainlines. This can have an affect on front shifting performance, the "Q factor" of the cranks, crank and chain stay clearance, etc.

    For a good explanation of chainline, read Sheldon Browns article here. All About Bicycle Chainline .

    Being that your bike is a Hybrid and not a road bike, you'll likely have to use a different spindle length than what is recommended to get the chainline correct for your set up.

    Good Dirt
    "I do whatever my Rice Cripsies tell me to!"

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