From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: chain stiffness data
Date: 2 Nov 1998 21:08:22 GMT

Damon Rinard writes:

> I thought some of you might like to know that I've just posted the
> lateral stiffness of a few bicycle chains on my web site at:

>      http://www.damonrinard.com/chain_stiffness.htm

I think this information would be more interesting if you had their
lateral flex of each chain when new and when 0.5% elongated.  This
would reveal more about the consistency of performance during its
usable life and might reveal what causes the change.

I has always been my experience that the more laterally flexible a
chain became the poorer it shifted.  In fact that was one of the early
criteria for replacing a chain when it no longer shifted easily due to
its ability to snake over to the sprocket it was on even though the
derailleur was aligned with the next gear.

As I said previously, the new Sachs derailleur chain is the worst
shifting chain I have come across because its pins and side plates are
beveled to reject climbing to the next sprocket.  The intent was
apparently to allow extreme crossover gearing with 9-speeds and triple
chainrings.  I am not impressed.  This is another case where the
demands of the incompetent bicyclist has prevailed over the riders who
use their equipment effectively.

Jobst Brandt      <jbrandt@hpl.hp.com>

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: chain stiffness data
Date: 3 Nov 1998 16:16:29 GMT

Hajo writes:

>> It has always been my experience that the more laterally flexible a
>> chain became the poorer it shifted.

> Shouldn't this be "torsionally flexible"?

Chains do not operate in a torsion mode.  That would be twisting the
chain about the long axis, a function that doesn't affect shifting.

Jobst Brandt      <jbrandt@hpl.hp.com>

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: chain stiffness data
Date: 4 Nov 1998 01:16:47 GMT

Hajo writes:

>> Chains do not operate in a torsion mode.

> Can't believe that. If I simulate a shift with my primitive methods
> on a bike, the chain twists.

The aversion to shifting occurs when the incoming chain from the
derailleur idler wheel is able to take a zigzag (laterally bending)
path to the sprocket with which it is no longer aligned in the attempt
to shift.  Obviously a lateral s-curve on a chain that is making a 90
degree bend around a small idler wheel causes some torsion in the
orthogonal run, but this is not significant and does not twist the
chain to its clearance limits.  That is, there is much more twist
clearance than is taken up by this effect and it is therefore not a
controlling factor.

>> That would be twisting the chain about the long axis, a function
>> that doesn't affect shifting.

> According to Bernhard Rohloff, the twisting has a big effect, easily
> recognizable when shifting under controlled conditions with a lab test
> stand.

As you know, I have many differences of opinion about chains.  Mine
come from years of experience with chains on bicycles and in design
and his seem not to conform to what I have learned about the subject.
Typically why a new chain skips on a worn driven sprocket and why a
worn chain skips on a new driving sprocket.  Also where the load on a
sprocket is concentrated, especially with a slightly worn chain.  If
this were as he predicts, then I could not ride a 19t sprocket on a
steep grade with three consecutive teeth missing.  On the other hand,
I don't expect him to carry out such experiments but they happen to
occur in normal bicycle riding with conventional equipment.

Jobst Brandt      <jbrandt@hpl.hp.com>

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: Cheaper chains best for drivetrain longevity?
Date: 4 Nov 1998 01:30:55 GMT

Jere C (who?) writes:

> Since it seems best for the drivetrain teeth to discard a chain
> frequently and replace it, why not run the cheapest chain that
> shifts well?  Won't a cheaper chain, being of less hard material
> (????) wear the cogs and chainwheels less that a harder more durable
> chain?  Or is it only the pins that are harder and last longer?  Or
> does an expensive chain indeed even last longer than a cheap chain,
> subjected to identical conditions of water, grit, and load, say an
> IG90 compared to an IG50???

Cheap chains, such as the Sachs standard derailleur chain, don't shift
well, so that is usually a dud.  If the chain also were made of poor
material, it would wear out rapidly and a wear elongated chain is what
ruins sprockets.  Therefore, it is not a good plan.  I don;t know what
the difference between those two chains is but I suspect it is only a
chrome finish on the side plates of the more expensive one.

Jobst Brandt      <jbrandt@hpl.hp.com>

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.racing
Subject: Re: Bushingless chains
Date: 19 Oct 1998 20:12:35 GMT

Nick Payne writes:

>> That's the only kind available for derailleur bicycles thanks to
>> the weight conscious bicycle owners who pay hundreds of dollars for
>> parts that are a gram or so lighter.

> Bushingless chains are cheaper to make, not more expensive, as they
> have less parts per link.

I didn't say they were cheaper, only that the pursuit of light weight
has brought us these chain that no other industry or vehicle would
consider because they wear out so fast.  The last bushing chain, the
Regina CX-S that I rode lasted for 20000 miles including two trips in
the Alps.  Today I use about five times as many chains for the same
service life.

To make up for the light weight and tensile strength, Sachs (formerly
Sedis) chains are the worst shifting chains made, because they have
beveled sides that enable gear freaks to ride extreme crossover on
8/9-speeds without popping out of gear.  As a result the chain will
not climb the next sprocket when a shift is desired.

Jobst Brandt      <jbrandt@hpl.hp.com>

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.racing
Subject: Re: Bushingless chains
Date: 20 Oct 1998 00:44:43 GMT

Bruce Hildenbrand writes:

>> To make up for the light weight and tensile strength, Sachs
>> (formerly Sedis) chains are the worst shifting chains made, because
>> they have beveled sides that enable gear freaks to ride extreme
>> crossover on 8/9-speeds without popping out of gear.  As a result
>> the chain will not climb the next sprocket when a shift is desired.

> Sedis chains shift just fine for me.  If somebody does not know how
> to shift their bike or they ride extreme crossover gear
> combinations, don't blame the chain manufacturer, blame the rider.

These are the recent Sachs chains (there is no mention of Sedis on
them) and they are beveled to not catch the teeth of adjacent sprockets
in extreme cross-over gears.  These chains do not shift even slightly
as well as the previous Sedis or other chains.  Your comment escapes my
parsing.  Are you saying that there are people who like inappropriate
gears or that the chain I describe is as good as other derailleur
chains.  I am sure you know how to shift, but that doesn't make this
chain a good one...  nor a durable one.

Jobst Brandt      <jbrandt@hpl.hp.com>