Chain / belt

Cycle chain
Components 101: Learn the basics about chain and belt-drives before we go all technical

Components 101: Chain/Belt

A bicycle chain is a roller chain that transfers energy very efficiently from the pedals to the wheels. Through prolonged use, a chain will wear resulting in chain ‘stretch’ where the links do not fit precisely into the spaces between the teeth in the drivetrain. This makes gear shifts ‘clunky’ and can cause the chain to 'skip', therefore reducing power transfer.

A belt-drive (also known as a chainless bike or a poly chain) is a continuous piece of reinforced rubber that transfers energy like a standard roller chain.  Its design is very similar to that of a timing belt found in certain cars, with moulded teeth on the inside which mesh with the cogs.

Advantages and Disadvantages of Belt-drive



  • Low maintenance – they require no lubrication.
  • Light weight - a poly chain weighs right around 55-grams (compared to a typical chain of 300-grams)
  • High yield strength - reinforced with synthetic threads (carbon or Kevlar), poly chains are harder to break than a chain.
  • Durable and economical – they have a longer life span than chains, (approx 8,000- to 10,000-miles).
  • No loss of power/efficiency – when compared with a chain drive.
  • Poor compatibility – currently only possible to run a singlespeed or internal hub gear. Derailleur systems are still in the research and development phase.
  • Specialised components required - special coatings or composites are used for contact points of the belt and the chainring/cog to reduce wear
  • Affected by cold weather –causing a poly chain to freeze up, therefore losing most of its flexibility.


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