On Aug 14, 9:57 am, "
[email protected]" <
[email protected]> wrote:
> so, conventional advice is, change chains often, save your cassette
>
> my question is, if chain wear were never a factor, how long would a
> cassette last?
>
> say you changed the chain every 100 miles
>
> the cassette is still bound to wear out some time, when would that be?
>
> wle.
Dear W,
Old-fashioned motorcycle primary chains ran in sealed oil baths. For
all practical purposes, such chains and gears lasted forever because
there was no grit in the oil to wear the metal surfaces.
It's the abrasive road dust whipped up by the tires that turns the oil
black on bicycle chains within ten miles and wears the moving parts of
the chain and the gear teeth.
The more the chain pins and rollers wear, the more the chain
lengthens, the more motion as they engage and disengage the gear
teeth, and the more work the abrasive grit can accomplish--the
transmission is just a gentle sanding machine that works better with
longer strokes.
Since your theoretical bicycle cassette is still exposed to road dust
carried by the new chain, the cassette will still eventually wear out,
but the gears will wear much more slowly because the constantly
renewed chain will not move as much as it engages and disengages from
the face of each gear tooth.
Replacing a chain every 100 miles would, of course, be pointless.
Assuming $10 chains, you'd spend $200 on chains in 2,000 miles in
hopes of lengthening the life of a cassette that cost well under $200.
More expensive cassettes usually involve more expensive chains, so
higher-priced equipment isn't going to change things, even if you
stopped every hundred miles to fit a new chain.
Cheers,
Carl Fogel