One way or another, water gets into bike frames and flows down hill to the bottom bracket. A drain hole lets it out. Without one, you can accumulate rust slurry which will kill your bearings when it tries to seep out through them.
@moth started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
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One way or another, water gets into bike frames and flows down hill to the bottom bracket. A drain hole lets it out. Without one, you can accumulate rust slurry which will kill your bearings when it tries to seep out through them.