SB20 - Bottom Bracket Failure

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The SB20 has a bottom bracket cartridge that is strong and reliable.

It is rare for a bottom bracket to fails. When it does, failure usually happens over time. It will initially degrade with subtle increases in friction and noise. This can be followed by lubricant leakage and then obvious mechanical looseness.

How to Isolate Failures 

Bottom bracket health is easy to assess. 

Remove the drive side cover and drive belt. 




Spin the cranks by hand.  They should be silent with no vibration.
There should be no friction.  Everything should be buttery smooth.

Fixing a Failed Bottom Bracket

Here's how replace the bottom bracket: SB20 - Replacing the Bottom Bracket.

Here's how to fix it, if you are so inclined: SB20 - How to Service the Bottom Bracket Cartridge. 

See also

If the belt is improperly tensioned or aligned you can feel friction when riding. Here's how to fix that:  

Flywheel bearing can also cause vibration.  See SB20 - Flywheel Cog and Axle Bearing Service.


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