Park chain checker--how to?
ph...@cruzio.com
instructions.
It consists of two posts inserted in a bar. One of the is mounted
eccentricly in a rotatable wheel. This allows the distance betwixt
the two 'posts' to be varied from a low of approx. 118 mm to a maximum
of about 122.5 mm.
One places the two posts into spaces between the links of his chain.
You then rotate the wheel, which is calibrated from 0 to 9, 0 being the
least distance betwen the posts, until the whole assembly is firmly
inserted in the links.
The calibration marks are blue in the zero to 3 range, then red for
the remainder, the >3 to 9 range.
Presumably, one would consider his chain to be rot when he gets into
the red zone. Here's the rub:
A *new* Sedisport ATB type chain already gives me a reading of nearly 2
on the gauge. Without documentation, I do not know what change in reading
I am allowed (delta) to classify a chain as "swell", "okay" or "rot".
Does anyone have any definitive knowledge about this tool to share?
Thanks loads
pH
Jobst Brandt
> I have purchased a Park CC1 Chain checker. It did not come with any
> instructions.
These tools are worthless because they measure the wrong thing. What
must be measured is the pitch of the chain and this thing measures the
clearance in the rollers by loading one roller in the opposite
direction from the other. A chain is used to pull in one direction on
one sprocket. What the chain does on the other end is immaterial on a
bicycle.
> A *new* Sedisport ATB type chain already gives me a reading of
> nearly 2 on the gauge. Without documentation, I do not know what
> change in reading I am allowed (delta) to classify a chain as
> "swell", "okay" or "rot".
Right there you have the proof of failure for this device. The pitch
of a new Sedis chain is about as accurately 0.5000 inch as you can get.
The measurement instrument is bogus.
> Does anyone have any definitive knowledge about this tool to share?
Use a ruler or yard stick. With the chain on the bicycle the inch
marks should line up with the chain pins exactly. A worn chain will
show a lengthening of up to 1/8 inch per foot, at which time you
should chuck it. I put on a new chain when it is between 1/16 and 1/8
somewhere. Beyond that you start rapid sprocket wear. On the other
hand, a worn chain will prevent chain suck for those who are afflicted
by this phenomenon.
Jobst Brandt <jbr...@hpl.hp.com>
Mark Huie
>phtp (anonymously) writes:
>
>> I have purchased a Park CC1 Chain checker. It did not come with any
>> instructions.
>
>These tools are worthless because they measure the wrong thing. What
>must be measured is the pitch of the chain and this thing measures the
>clearance in the rollers by loading one roller in the opposite
>direction from the other. A chain is used to pull in one direction on
>one sprocket. What the chain does on the other end is immaterial on a
>bicycle.
After drawing a lot of little circles on paper, I would beg to
differ.
Taking the extreme case of the rollers being very worn, that means
that even a chain with perfect pitch when wrapped around a
sprocket would be trying to trace a slightly smaller circle around the
sprocket than the sprocket is designed for. (read: the circle around
a sprocket traced by the pins of a chain with worn rollers is going
to be smaller than the circle traced by a chain without worn rollers)
This is going to result in increased loading on the leading tooth
because at that decreased radius, the other rollers aren't contacting
the teeth as well. This problem becomes more pronounced for smaller
radaii (fewer teeth), and conversely, it disappears in the limiting
case where the chain is pulling on a linear set of teeth (read:
infinite radius sprocket).
Imperfect pitch is a problem in both cases: pulling around a small
sprocket and pulling along in a straight line, so maybe the
roller play is a higher order effect, but the tool still takes
into account the increase in pitch of a worn chain.
I figure the roller play has a significant enough effect on wear.
I've had chains that have not stretched 1/16" per foot and still
experienced a lot of sprocket wear.
>> A *new* Sedisport ATB type chain already gives me a reading of
>> nearly 2 on the gauge. Without documentation, I do not know what
>> change in reading I am allowed (delta) to classify a chain as
>> "swell", "okay" or "rot".
>
>Right there you have the proof of failure for this device. The pitch
>of a new Sedis chain is about as accurately 0.5000 inch as you can get.
>The measurement instrument is bogus.
Or it's telling you that the chain isn't perfect (but what is?) and
the rollers are slightly off (whether it's excessively off is up
to you), but it's probably within manufacturer's specifications.
It just occurred to me that, yes, the roller play may be a higher
order effect and the way the manufacturer (Park or Rholoff, since
they make a similar tool too) increases the weighting of the effect
of the pitch is to make the tool longer since you're only measuring
the play of only two rollers, but you can measure the pitch stretch
over a number of links, each additive.
>Use a ruler or yard stick. With the chain on the bicycle the inch
>marks should line up with the chain pins exactly. A worn chain will
>show a lengthening of up to 1/8 inch per foot, at which time you
>should chuck it. I put on a new chain when it is between 1/16 and 1/8
>somewhere. Beyond that you start rapid sprocket wear. On the other
>hand, a worn chain will prevent chain suck for those who are afflicted
>by this phenomenon.
Park made a tool to do this. I wonder why they came out with a new
tool if the old one worked fine (unless the old one didn't work as well?)
But don't ask me to explain the rholoff chain. Supposedly it has cams
inside it to allow the rollers to seat on the cog better, but I'd assume
that'd allow it to wear faster, however, I've heard that rholoff chains
actually last longer. (okay the cam/seating stuff was my interpretation,
but that was the general impression I got form their ads)
But they make a tool to check for this kind of wear, so they know
about the roller wear effects, and I guess they know to design
around it.
I assume the best way to measure the wear is to put the tool around
a circular gauge to best simulate the conditions where wear will
occur. I guess that's where the "shift the bike onto the largest
chainring. Midway on the chainring, lift up/out on the chain. If you
can pull it out 1/X inches, replace it" method works (now, how do you
make a "pasa/no-pasa" tool to do that?)
-huie
Sutherland's Bicycle Shop Aids
--
Mark Huie After all is said and done,
mh...@netcom.com more is said than done.
Jobst Brandt
>> These tools are worthless because they measure the wrong thing. What
>> must be measured is the pitch of the chain and this thing measures the
>> clearance in the rollers by loading one roller in the opposite
>> direction from the other. A chain is used to pull in one direction on
>> one sprocket. What the chain does on the other end is immaterial on a
>> bicycle.
> After drawing a lot of little circles on paper, I would beg to
> differ. Taking the extreme case of the rollers being very worn,
> that means that even a chain with perfect pitch when wrapped around
> a sprocket would be trying to trace a slightly smaller circle around
> the sprocket than the sprocket is designed for. (read: the circle
> around a sprocket traced by the pins of a chain with worn rollers is
> going to be smaller than the circle traced by a chain without worn
> rollers)
So what? This only means that, on a 40t or larger chainwheel, the
chain can exit under no load. The first few rollers carry most of the
load anyway. Besides, the wear is concentrated in every other roller
because the roller pairs are on a common link whose length does not
change. Therefore, the load is generally carried by two rollers when
the chain starts wearing its pitch longer.
> This is going to result in increased loading on the leading tooth
> because at that decreased radius, the other rollers aren't contacting
> the teeth as well. This problem becomes more pronounced for smaller
> radaii (fewer teeth), and conversely, it disappears in the limiting
> case where the chain is pulling on a linear set of teeth (read:
> infinite radius sprocket).
his is just one of the imperfections that come with the territory.
The difference is not enough to prevent chain suck apparently so it
can't be large for a new chain and it affects small chainwheels more
than large one because it its the small ones (18-22t) that seem to
have the greatest problems with a new chain whose pitch is such that
the exit teeth are still under load.
> Imperfect pitch is a problem in both cases: pulling around a small
> sprocket and pulling along in a straight line, so maybe the
> roller play is a higher order effect, but the tool still takes
> into account the increase in pitch of a worn chain.
Oh, how? If it pushes one roller fore and the other aft, I see the roller
play entering the measurement. Why not just use a yard stick? We are
interested in a qualitative measure of chain wear, not the precise current
pitch length.
> I figure the roller play has a significant enough effect on wear.
> I've had chains that have not stretched 1/16" per foot and still
> experienced a lot of sprocket wear.
That depends on the environment and lubrication. I don't think I have
enough controlled experimental data to say that I have observed this.
>>> A *new* Sedisport ATB type chain already gives me a reading of
>>> nearly 2 on the gauge. Without documentation, I do not know what
>>> change in reading I am allowed (delta) to classify a chain as
>>> "swell", "Okay" or "rot".
>>
>> Right there you have the proof of failure for this device. The pitch
>> of a new Sedis chain is about as accurately 0.5000 inch as you can get.
>> The measurement instrument is bogus.
> Or it's telling you that the chain isn't perfect (but what is?) and
> the rollers are slightly off (whether it's excessively off is up
> to you), but it's probably within manufacturer's specifications.
Of that I am sure. The pitch of a new Sedis chain is dead accurate to
within less than 0.05 mm, certainly less than this tool can resolve.
> It just occurred to me that, yes, the roller play may be a higher
> order effect and the way the manufacturer (Park or Rohloff, since
> they make a similar tool too) increases the weighting of the effect
> of the pitch is to make the tool longer since you're only measuring
> the play of only two rollers, but you can measure the pitch stretch
> over a number of links, each additive.
Yes, that's why using a yardstick over 12 inches is so simple. The
reason these tools exist is that you can't find a yardstick (or any
other inch device)in Europe.
> But don't ask me to explain the Rohloff chain. Supposedly it has cams
> inside it to allow the rollers to seat on the cog better, but I'd assume
> that'd allow it to wear faster, however, I've heard that Rohloff chains
> actually last longer. (Kay the cam/seating stuff was my interpretation,
> but that was the general impression I got form their ads)
> But they make a tool to check for this kind of wear, so they know
> about the roller wear effects, and I guess they know to design
> around it.
Rohloff merely has a dual diameter hole formed in the side plates so
that the pin exactly fits the radius of the hole around about 1/3 the
circumference of the hole while the remainder of the hole is enlarged.
This way there is clearance at the same time the pin has almost a press
fit in its bearing zone. This feature is so small that any other chain
achieves this condition in a few miles of hard use, but it is a nice
thought. I prefer not to pay for the thought.
> I assume the best way to measure the wear is to put the tool around
> a circular gauge to best simulate the conditions where wear will
> occur. I guess that's where the "shift the bike onto the largest
> chainring. Midway on the chainring, lift up/out on the chain. If you
> can pull it out 1/X inches, replace it" method works (now, how do you
> make a "pasa/no-pasa" tool to do that?)
I don't think that is a good idea. I trust the chain makers that in
the last 100 years, they have figured it out and my ruler tells me
about when to get another one. The main thing is that chains work and
then they wear out, regardless of the expensive instrumentation that
you buy.
Jobst Brandt <jbr...@hpl.hp.com>