| Re: Replace whole chainset if replace front chainring?
This applies to bicycles, motorcycles, chainsaws, and anything else where
power is delivered through a chain drive. A new chain, running on a new
sprocket, ideally, makes equal contact with all the teeth that are engaged.
As the chain wears, the pitch increases, so the load is carried more by the
teeth that are just coming into mesh. Of course, the sprocket wears also,
so the load tends to be properly carried by all the teeth. If you now
replace just the chain, the pitch will be shorter than the sprocket pitch,
and all the load will be carried by the teeth that are just going out of
mesh. The wear on the chain and teeth will be rapid. Since the sprocket is
already worn, any metal that it loses will make the problem worse, not
better, so the problem gets worse. The new chain won't last very long.
In practice, chains seem to wear out more rapidly than sprockets, so you can
get away with changing the chain more often than the sprocket. On
chainsaws, the ratio is about three to one. I don't know what it is on
bicycles. On chainsaws, the best practice is to rotate three chains in
service, so they all wear out together, and then replace all three AND the
sprocket. I have never heard of anyone doing this on a bicycle, but,
theoretically, it sounds like a plan.
Comments?
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