My 5 year old asked me this – Why do all bicycles have the chains on one side only?


I tried answering, maybe something to do with being right handed etc. but nothing really made much sense. So why did we achieve such consistency in bicycle design, while we struggle with other things (metric Vs Imperial, left hand Vs right hand drive cars)?

In: 32

Old style cassettes (cog on back wheel) were screwed into the hub, having the drivetrain on the right means chain pressure tightens the cassette instead of loosening it. Using modern designs there is no advantage, but LHD needs twice the number of frame, chainring, cassette, derailleur and hub designs.

In the last decade or so left hand drive BMXs have become available, these keep the drivetrain out of the way when grinding if you prefer to grind on the right side of the bike, this makes the extra design time worth it.

Good: chain/gear longevity since pressure is split
Bad: increased weight, increased maintenance complextiy, ugly

Left side drive (lsd) bikes do exist! In the single speed track bike and freestyle bmx space the drivetrain is moved to the other side for aerodynamic reasons and to get it out of the way for grinding tricks.