W
Werehatrack
Guest
On Wed, 25 Feb 2004 04:10:45 GMT, meb <[email protected]>
may have said:
>carlfogel said:
>
>"This is unsurprising. Rollers presumably roll."
>
>Maybe with an poorly oiled chain they don't roll. Anyone got a neglected chain they can measure
>both ways?
As a matter of fact, there's a bike in the salvage pile with a neglected chain. It had no master
link, so I suspect the chain had never been off until just now. It measured 1.1mm longer than a
brand new chain between the two most widely separated links my calipers could reach. Flipping it
over produced the exact same result.
>The pins don't roll, so one would expect more wear on one side.
Why? There is *no significant tension* on the part of the chain that is on the curve of the
sprockets. Wear will occur where there is high load or *unlubricated* motion. If the chain is
reasonably well lubed, the flexing of the chain as it goes around the sprockets should produce
little or no wear. All of the tension of pedalling is transmitted along the top *straight* run of
the chain between the tooth bearing the load at the top of the rear sprocket and the tooth
delivering the load at the chainwheel. Regardless of which way the chain is flipped, the load is on
the same place on each link and pin.
(I will note that there is actually a slight skewing to the inside on the wear due to the fact that
as the sprockets turn, the load may be on a pin whose link has not yet fully rotated into alignment
with the top run...but this *small* skewing is not enough to make a flipped chain "fit like new"
when it was worn out as measured.)
>Since the pins are made of harder materials though, it would seem the chain has long since passed
>its useful life before measurable differences appear.
The wear is hard to measure at a single link, but that's why it's measured for aggregate total over
a long section. I suspect that if the originator of the topic was checking for chain lift
availability at the front of the chainring as a (false) measure of chain wear, there may have
appeared to be a difference when the chain was first flipped. I also suspect that as soon as the
chain was ridden a distance, driving the dirt out of the links, the difference would have vanished.
--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.
may have said:
>carlfogel said:
>
>"This is unsurprising. Rollers presumably roll."
>
>Maybe with an poorly oiled chain they don't roll. Anyone got a neglected chain they can measure
>both ways?
As a matter of fact, there's a bike in the salvage pile with a neglected chain. It had no master
link, so I suspect the chain had never been off until just now. It measured 1.1mm longer than a
brand new chain between the two most widely separated links my calipers could reach. Flipping it
over produced the exact same result.
>The pins don't roll, so one would expect more wear on one side.
Why? There is *no significant tension* on the part of the chain that is on the curve of the
sprockets. Wear will occur where there is high load or *unlubricated* motion. If the chain is
reasonably well lubed, the flexing of the chain as it goes around the sprockets should produce
little or no wear. All of the tension of pedalling is transmitted along the top *straight* run of
the chain between the tooth bearing the load at the top of the rear sprocket and the tooth
delivering the load at the chainwheel. Regardless of which way the chain is flipped, the load is on
the same place on each link and pin.
(I will note that there is actually a slight skewing to the inside on the wear due to the fact that
as the sprockets turn, the load may be on a pin whose link has not yet fully rotated into alignment
with the top run...but this *small* skewing is not enough to make a flipped chain "fit like new"
when it was worn out as measured.)
>Since the pins are made of harder materials though, it would seem the chain has long since passed
>its useful life before measurable differences appear.
The wear is hard to measure at a single link, but that's why it's measured for aggregate total over
a long section. I suspect that if the originator of the topic was checking for chain lift
availability at the front of the chainring as a (false) measure of chain wear, there may have
appeared to be a difference when the chain was first flipped. I also suspect that as soon as the
chain was ridden a distance, driving the dirt out of the links, the difference would have vanished.
--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.