Cyclometer and Cargo Bikes...

On Saturday, August 26, 2017 at 1:37:53 PM UTC-7, Joerg wrote:
On 2017-08-26 13:25, jbeattie wrote:
On Saturday, August 26, 2017 at 11:54:15 AM UTC-7, Joerg wrote:
On 2017-08-26 10:15, jbeattie wrote:

[...]



... Is your time not worth anything?


How does the above procedure cost much time?

That does not tell you the torque at the fastener. It tells you the
downward force on a lever arm. You need to calculate the torque --
which I'm sure you do in your head, like a super-computer, taking
into consideration the bending of the wrench, movement of the earth,
precession of the moon.


The wrench handle is 8" long. A foot is 12". So one has to multiply by
1.5. Man, that's complicated.

I know schools and math proficiency are bad these days and kids might
not be able to multiply by 1.5 in their heads but I thought you were a
bit older and thus know how to do that :-)

Hmmm, now convert that to Newton Meters and/or Inch Pounds -- and hold the wrench and hook the scale around the wrench arm at a fixed distance -- don't let it slide around, calculate the effect of the angle between the scale hook and the lever arm as the fastener rotates. Factor in the wire digging into your palm/fingers as you struggle to get 34.67 lbs divided by 1.5 pounds of force through the hook and into the wrench. https://tinyurl.com/y7n5dvkc




Reality check: how many times have you gone into a bike shop, auto
repair or any other shop where fasteners are regularly tightened --
say Les Schwab Tire -- and seen them using a luggage scale instead of
a torque wrench?


Reality check #1: Those people do this every day, all day long. They
probably even have automated electric or pneumatic torque limiters.

Reality check #2: You and I are not car mechanics. How often do you use
a torque wrench?

Maybe five times today. I'm building my CAADX. SRAM 10mm bolt 47nm, stem/bar clamp bolts 5nm (different torque wrench). 8nm on the steerer compression nut. I use it twice a year for the lug nuts on my snow tire/summer tire swap. On my Shimano bikes, I'm scrupulous about the bolt torque on the cranks. I'll use it on the brake post-mount bolts -- as soon as I get some spacers. I'm so ****ed that the frame has 140mm-sized posts. I use 160mm front rotors.

No, I don't use my torque wrenches every day. I also don't use my Park tensiometer or my headset press or any of a multitude of tools every day. But, OTOH, I don't fix things with rocks and Walmart baggage scales.

If you are trashing your bikes with the vigor you claim, then you should have appropriate tools for repair. This is, after all, a bicycle repair NG. All of the various bolts on your swing arms and shocks and seat post and stem clamps have torque specs. It now matters to get those right -- not so much in the ham-handed steel days, but it does now.

-- Jay Beattie.

On 8/26/2017 2:46 PM, Joerg wrote:
On 2017-08-26 10:20, jbeattie wrote:


[JB:] You know for $18 a torque wrench isn't a bank breaking tool.


[Joerg:] However, it does not have such an accurate digital display as my
solution :-)

There are people who think that anything with a digital display
must be more accurate than anything with an analog display.Â* Those
people are simply wrong. Accuracy is affected by the design of the
entire system, not merely the display.


I thought you were an engineer.

1. Those things can easily be calibrated. When I checked mine it was
right on the money over the whole range needed, as checked versus
commercial grade scales (those where the government hands out fines if
inaccurate). You can also used known weights. It's easy.

2. I design electronics for a living so I know full well when something
is accurate, digital or analog.

Sorry, Joerg, designing electronics doesn't necessarily qualify you to
know about accuracy of measuring tools. "It does not have such an
accurate digital display as my solution" certainly seems to imply that
"digital" means "accurate." But digital devices are not necessarily
accurate. Hell, I've got two digital thermometers that never read the
same, and for a while one of them was inexplicably off by twelve degrees
Fahrenheit, and neither was cheap.

Sure, you can buy a $20 luggage scale instead of a $20 torque wrench,
and kludge around to make the scale sort of work in some situations. I
suppose that might actually be smart if you needed to work on your
bottom bracket next to the Brookstone store inside an airport. Otherwise
it's far from smart.

3. A torque wrench has sufficient accuracy for such jobs. The suitcase
scale has way more accuract and, therefore, its accuracy is way more
than sufficient for the job.

"The suitcase scale has way more accuract," does it? Hmm.

Example:Â* I once dissected a bathroom scale that had a digital
display. That one had precisely the same collection of levers and
springs found in an analog bathroom scale; but instead of rotating
a disk printed with numbers, it rotated a sort of encoder wheel.
The electronics read the encoder and flashed the LED numerals. It
was all for show, with perhaps a slight benefit regarding reading
numbers in dim light.Â* Or perhaps helping people who can't
interpolate using the little marks between 210 and 215.


Probably you buy that at some discount store. Proper digital scales have
real pressure sensors. This kind:

https://media.digikey.com/pdf/Data%2...990100_Web.pdf

That's not a "pressure sensor." It's a "weight sensor" or "load cell."
(I thought you were an engineer!) If you don't know the terminology for
the quantities being measured, I doubt you know much about accuracy -
certainly not enough to judge whether your kludge is more accurate than
a torque wrench.

Again, the overall accuracy of the system is what matters, and I
strongly suspect you're ignoring sources of error in order to pat
yourself on the back.

Not that it's critical. As you say, if the torque wrench is within 5%
it's probably fine. Your kludge can certainly get within 5% - given
enough time to get everything oriented right, keep the bike solidly in
place, prevent the lever arm and scale from slipping, do whatever mental
math may be needed, re-orient if the lever arm rotates too far, etc.

But those of us that actually work competently on bikes and other
mechanical things would never kludge around that way. For us, a torque
wrench is FAR more useful than a luggage scale. (That's especially true
for a guy who repeatedly says he "doesn't care about weight.")

But then, a chain tool is also far more useful than a rock and a nail.
And hey, a torque wrench can be used to beat off the mountain lions!

--
- Frank Krygowski

On 23/08/17 15:37, dave wrote:
On Tue, 22 Aug 2017 07:33:03 -0700, Joerg wrote:

snip

Then I'd crash trying to beat my current max speed :-)

Heh!

My best is 68kmh. (googles) 42.25mph.


On a Bullitt cargo bike? Wow! That I would not dare to do. Was that with
a load?

Not really laden. Standard bag of crap; water, tools, book etc. Down
hill. This hill in fact. https://goo.gl/iBp2Dn It does have a steering
damper which makes it way less scary.

I was careering down a short steep hill yesterday, laden with about 20
kilos, I might have a look at a steering damper.

On Sat, 26 Aug 2017 11:26:29 -0400, Frank Krygowski
wrote:

On 8/26/2017 10:55 AM, Joerg wrote:
On 2017-08-26 07:17, wrote:
On Friday, August 25, 2017 at 12:50:12 PM UTC-7, Joerg wrote:


[...]

* But you can use a rock and a nail -- but make sure its an old square
nail and the rock has a high feldspar content. You'll know when its
up to torque when the rock starts breaking apart -- and an owl passes
across the moon, and the great spirit sends you a signal. Or you
could get a torque wrench.


I like multi-purpose tools :-)

https://www.amazon.co.uk/Portable-Ha.../dp/B00C68JD3Y


I was surprised how accurate those are. Weighed a suitcase at 49.0lbs.
Lifted it onto the baggage check scales at UAL, with that white-knuckle
feel that it might be over. Nope, their display also showed 49.0lbs. On
the way back I weighed it with another such device in Europe and same
thing at the Lufthansa check-in counter, the weight was right on the
money.

https://www.walmart.com/ip/Neiko-Bea...l13=&veh= sem


You know for $18 a torque wrench isn't a bank breaking tool.


However, it does not have such an accurate digital display as my
solution :-)

There are people who think that anything with a digital display must be
more accurate than anything with an analog display. Those people are
simply wrong. Accuracy is affected by the design of the entire system,
not merely the display.

Example: I once dissected a bathroom scale that had a digital display.
That one had precisely the same collection of levers and springs found
in an analog bathroom scale; but instead of rotating a disk printed with
numbers, it rotated a sort of encoder wheel. The electronics read the
encoder and flashed the LED numerals. It was all for show, with perhaps
a slight benefit regarding reading numbers in dim light. Or perhaps
helping people who can't interpolate using the little marks between 210
and 215.

In the case of your kludge: The digital luggage scale may use a simple
spring as a transducer, just as that bath scale did, and be no more
accurate than a spring scale. If instead it has a system based on
strain gages or other such technology, it may or may not have proper
temperature compensation. If it actually is very accurate, your kludge
also depends on your positioning of the scale on your wrench or other
lever arm, and I'd suspect your precision in placing it at exactly 8"
(or wherever) is less than stellar. And if you do place it at precisely
the right location, you also need to pull precisely perpendicular to the
lever arm. Of course, as the lever arm rotates, you must maintain that
perpendicularity, and your eyeballs may not be as good at that as you
probably believe.

OTOH, for a bottom bracket retainer, the torque really isn't all that
critical. Rather than fuss around with a weird kludge, I'd either judge
the tightness by hand, or do what I actually did - which was just buy a
blasted torque wrench, and do it nearly 50 years ago.


But Frank. Anyone can go out and buy a torque wrench. It takes a
person with fertile imagination to take a bit of string and a banana
peel and believe that they have done something remarkable :-)
--
Cheers,

John B.

On Sat, 26 Aug 2017 13:25:29 -0700 (PDT), jbeattie
wrote:

On Saturday, August 26, 2017 at 11:54:15 AM UTC-7, Joerg wrote:
On 2017-08-26 10:15, jbeattie wrote:
On Saturday, August 26, 2017 at 7:55:09 AM UTC-7, Joerg wrote:
On 2017-08-26 07:17, wrote:
On Friday, August 25, 2017 at 12:50:12 PM UTC-7, Joerg wrote:


[...]

But you can use a rock and a nail -- but make sure its an old
square nail and the rock has a high feldspar content. You'll
know when its up to torque when the rock starts breaking
apart -- and an owl passes across the moon, and the great
spirit sends you a signal. Or you could get a torque wrench.


I like multi-purpose tools :-)

https://www.amazon.co.uk/Portable-Ha.../dp/B00C68JD3Y



I was surprised how accurate those are. Weighed a suitcase at 49.0lbs.
Lifted it onto the baggage check scales at UAL, with that
white-knuckle feel that it might be over. Nope, their display
also showed 49.0lbs. On the way back I weighed it with another
such device in Europe and same thing at the Lufthansa check-in
counter, the weight was right on the money.

https://www.walmart.com/ip/Neiko-Bea...l13=&veh= sem



You know for $18 a torque wrench isn't a bank breaking tool.


However, it does not have such an accurate digital display as my
solution :-)

Your solution is s f****** luggage scale. Even a cheap torque wrench
will be a wrench -- something that you can put a hex socket on and
that will get you within the specified torque range. It's not brain
surgery or airline travel. It's bike repair.

I just put on a crank -- SRAM with a 10mm socket 43-47 NM. I did it
with a nice Craftsman torque wrench my wife gave me as a Christmas
gift. It replaced the $20 beam wrench I bought 20+ years ago. Five
minute job -- no attempting to use a 6" socket wrench, torqued with a
full suitcase hanging off a luggage scale or some other kludge.


How do you guys get this "hanging a suitcase" idea all the time? My
suitcases stay in the walk-in closets unless I need to travel. The the
suitcase scale doubles as a tool to prevent a nasty surprise and fee at
the airline check-in counter.

It is also useful to determine how much water I got in a bucket for
brewing, something that does have to be quite accurate as well.

This li'l device has lots of uses.


How do you even make that work?


Simple: Click wrench handle into Shimano BB socket, stick into BB cup,
screw that in until quite tight, slip suitcase scale loop over the
grooved or knurled end (depending on whether I use the ratcheting on
non-ratcheting handle), push button, pull while looking at display. When
display reads target number, stop. Do the same on the non-drive side. Done.


... Is your time not worth anything?


How does the above procedure cost much time?

That does not tell you the torque at the fastener. It tells you the downward force on a lever arm. You need to calculate the torque -- which I'm sure you do in your head, like a super-computer, taking into consideration the bending of the wrench, movement of the earth, precession of the moon.

Reality check: how many times have you gone into a bike shop, auto repair or any other shop where fasteners are regularly tightened -- say Les Schwab Tire -- and seen them using a luggage scale instead of a torque wrench? Why do you persist in claiming that a Chinese POS luggage scale is as good as a real torque wrench? I don't get why all the kludging is a point of pride. It's like being proud of using newspaper for underwear or a Glad bag for rain gear.

-- Jay Beattie.

Actually I have used a scale and a wrench with a one foot mark on it
to train beginning mechanics. This was in Indonesia where the
mechanics we were training literally didn't know how to screw a not on
a bolt when they started training and the concept of "foot pounds" was
simply incomprehensible to them.

As an aside they weren't familiar with electricity or pressure, either
hydraulic or air :-)

Which gives one a bit of an insight into the level of technical
knowledge involved :-)

--
Cheers,

John B.

On Sat, 26 Aug 2017 07:55:34 -0700, Joerg
wrote:

On 2017-08-26 07:17, wrote:
On Friday, August 25, 2017 at 12:50:12 PM UTC-7, Joerg wrote:


[...]

But you can use a rock and a nail -- but make sure its an old square
nail and the rock has a high feldspar content. You'll know when its
up to torque when the rock starts breaking apart -- and an owl passes
across the moon, and the great spirit sends you a signal. Or you
could get a torque wrench.


I like multi-purpose tools :-)

https://www.amazon.co.uk/Portable-Ha.../dp/B00C68JD3Y

I was surprised how accurate those are. Weighed a suitcase at 49.0lbs.
Lifted it onto the baggage check scales at UAL, with that white-knuckle
feel that it might be over. Nope, their display also showed 49.0lbs. On
the way back I weighed it with another such device in Europe and same
thing at the Lufthansa check-in counter, the weight was right on the money.

https://www.walmart.com/ip/Neiko-Bea...l13=&veh= sem

You know for $18 a torque wrench isn't a bank breaking tool.


However, it does not have such an accurate digital display as my
solution :-)

But does it need it? If I recall the Octalink was tightened to 35 - 50
Nm... that is a pretty wide range isn't it? Does one need a digital
readout and an magnifying glass to get it right?
--
Cheers,

John B.

On 2017-08-26 20:15, Frank Krygowski wrote:
On 8/26/2017 2:46 PM, Joerg wrote:
On 2017-08-26 10:20, jbeattie wrote:


[JB:] You know for $18 a torque wrench isn't a bank breaking tool.


[Joerg:] However, it does not have such an accurate digital display
as my
solution :-)

There are people who think that anything with a digital display
must be more accurate than anything with an analog display. Those
people are simply wrong. Accuracy is affected by the design of the
entire system, not merely the display.


I thought you were an engineer.

1. Those things can easily be calibrated. When I checked mine it was
right on the money over the whole range needed, as checked versus
commercial grade scales (those where the government hands out fines if
inaccurate). You can also used known weights. It's easy.

2. I design electronics for a living so I know full well when
something is accurate, digital or analog.

Sorry, Joerg, designing electronics doesn't necessarily qualify you to
know about accuracy of measuring tools.


It does if you design measuring tools. Why I do.


..."It does not have such an
accurate digital display as my solution" certainly seems to imply that
"digital" means "accurate."


I never said or implied that. What you sometimes imply is, to say it
politely, weird.


... But digital devices are not necessarily
accurate. Hell, I've got two digital thermometers that never read the
same, and for a while one of them was inexplicably off by twelve degrees
Fahrenheit, and neither was cheap.


Then you bought junk. Digital thermometers of the lower price ranges
mostly contain NTC or thermally-dependent resistors. Those can have
tolerances up to a few percent depending on grade. Still you can make a
good product with those and I just bought one example from China. The
three external radio sensors were withing +/-1F. The isnide unit was
2.3F off. However, there was a method of entering a correction value
and, voila.


Sure, you can buy a $20 luggage scale instead of a $20 torque wrench,
and kludge around to make the scale sort of work in some situations. I
suppose that might actually be smart if you needed to work on your
bottom bracket next to the Brookstone store inside an airport. Otherwise
it's far from smart.


You just don't understand it. The procedure is very simple.


3. A torque wrench has sufficient accuracy for such jobs. The suitcase
scale has way more accuract and, therefore, its accuracy is way more
than sufficient for the job.

"The suitcase scale has way more accuract," does it? Hmm.


Look it up. Torque wrenched at easily 5% off and that often applies to
full scale. The $20 jobs are probably worse. And yes, my suitcase scale
is more accurate than that _and_ can easily be calibrated.


Example: I once dissected a bathroom scale that had a digital
display. That one had precisely the same collection of levers and
springs found in an analog bathroom scale; but instead of rotating
a disk printed with numbers, it rotated a sort of encoder wheel.
The electronics read the encoder and flashed the LED numerals. It
was all for show, with perhaps a slight benefit regarding reading
numbers in dim light. Or perhaps helping people who can't
interpolate using the little marks between 210 and 215.


Probably you buy that at some discount store. Proper digital scales
have real pressure sensors. This kind:

https://media.digikey.com/pdf/Data%2...990100_Web.pdf


That's not a "pressure sensor." It's a "weight sensor" or "load cell."


Sorry, that's what I meant. Mixed it up with a project I just did that
used a pressure sensor.


(I thought you were an engineer!) If you don't know the terminology for
the quantities being measured, I doubt you know much about accuracy -
certainly not enough to judge whether your kludge is more accurate than
a torque wrench.


Phhht ...


Again, the overall accuracy of the system is what matters, and I
strongly suspect you're ignoring sources of error in order to pat
yourself on the back.

Not that it's critical. As you say, if the torque wrench is within 5%
it's probably fine. Your kludge can certainly get within 5% - ...


See? You finally understand it?


... given
enough time to get everything oriented right, keep the bike solidly in
place, prevent the lever arm and scale from slipping, do whatever mental
math may be needed, re-orient if the lever arm rotates too far, etc.


It's simple. You slip the loop over where the groove resp. knurled area
is, pull and read the numbers. That's it.


But those of us that actually work competently on bikes and other
mechanical things would never kludge around that way. For us, a torque
wrench is FAR more useful than a luggage scale. (That's especially true
for a guy who repeatedly says he "doesn't care about weight.")

But then, a chain tool is also far more useful than a rock and a nail.
And hey, a torque wrench can be used to beat off the mountain lions!


Bear spray is easier.

--
Regards, Joerg

http://www.analogconsultants.com/

On 2017-08-26 16:40, jbeattie wrote:
On Saturday, August 26, 2017 at 1:37:53 PM UTC-7, Joerg wrote:
On 2017-08-26 13:25, jbeattie wrote:
On Saturday, August 26, 2017 at 11:54:15 AM UTC-7, Joerg wrote:
On 2017-08-26 10:15, jbeattie wrote:

[...]



... Is your time not worth anything?


How does the above procedure cost much time?

That does not tell you the torque at the fastener. It tells you
the downward force on a lever arm. You need to calculate the
torque -- which I'm sure you do in your head, like a
super-computer, taking into consideration the bending of the
wrench, movement of the earth, precession of the moon.


The wrench handle is 8" long. A foot is 12". So one has to multiply
by 1.5. Man, that's complicated.

I know schools and math proficiency are bad these days and kids
might not be able to multiply by 1.5 in their heads but I thought
you were a bit older and thus know how to do that :-)

Hmmm, now convert that to Newton Meters and/or Inch Pounds -- and
hold the wrench and hook the scale around the wrench arm at a fixed
distance -- don't let it slide around, calculate the effect of the
angle between the scale hook and the lever arm as the fastener
rotates. Factor in the wire digging into your palm/fingers as you
struggle to get 34.67 lbs divided by 1.5 pounds of force through the
hook and into the wrench. https://tinyurl.com/y7n5dvkc


What struggle? Of course, my scale does not have a hook but a real
handle, with finger indents for a better grip. You can always find a
picture of a botched design but you do not have to buy that product. At
least I don't. Mine is from these guys:

http://www.testrite.de/index.php/en/

Whether they bought the design or designed it themselves I don't know
and I don't care because I have verified that it is accurate.


Reality check: how many times have you gone into a bike shop,
auto repair or any other shop where fasteners are regularly
tightened -- say Les Schwab Tire -- and seen them using a luggage
scale instead of a torque wrench?


Reality check #1: Those people do this every day, all day long.
They probably even have automated electric or pneumatic torque
limiters.

Reality check #2: You and I are not car mechanics. How often do you
use a torque wrench?

Maybe five times today. I'm building my CAADX. SRAM 10mm bolt 47nm,
stem/bar clamp bolts 5nm (different torque wrench). 8nm on the
steerer compression nut. I use it twice a year for the lug nuts on my
snow tire/summer tire swap. On my Shimano bikes, I'm scrupulous
about the bolt torque on the cranks.


So am I, for the square taper and even more so the Octalink on the MTB.
But I only check that once a few weeks after install and after that
maybe 1-2 times/year.


... I'll use it on the brake
post-mount bolts -- as soon as I get some spacers. I'm so ****ed
that the frame has 140mm-sized posts. I use 160mm front rotors.


I use 7" or about 180mm up front but would rather move to 8". 140mm is
something I'd consider totally inadequate for anyone whose bike sees
some utility use like both of mine do.


No, I don't use my torque wrenches every day. I also don't use my
Park tensiometer or my headset press or any of a multitude of tools
every day. But, OTOH, I don't fix things with rocks and Walmart
baggage scales.

If you are trashing your bikes with the vigor you claim, then you
should have appropriate tools for repair. This is, after all, a
bicycle repair NG. All of the various bolts on your swing arms and
shocks and seat post and stem clamps have torque specs. It now
matters to get those right -- not so much in the ham-handed steel
days, but it does now.


That's why my luggage scale is always very close to where I repair my
bikes :-)

--
Regards, Joerg

http://www.analogconsultants.com/

On 2017-08-27 06:17, John B. wrote:
On Sat, 26 Aug 2017 07:55:34 -0700, Joerg
wrote:

On 2017-08-26 07:17, wrote:
On Friday, August 25, 2017 at 12:50:12 PM UTC-7, Joerg wrote:


[...]

But you can use a rock and a nail -- but make sure its an old square
nail and the rock has a high feldspar content. You'll know when its
up to torque when the rock starts breaking apart -- and an owl passes
across the moon, and the great spirit sends you a signal. Or you
could get a torque wrench.


I like multi-purpose tools :-)

https://www.amazon.co.uk/Portable-Ha.../dp/B00C68JD3Y

I was surprised how accurate those are. Weighed a suitcase at 49.0lbs.
Lifted it onto the baggage check scales at UAL, with that white-knuckle
feel that it might be over. Nope, their display also showed 49.0lbs. On
the way back I weighed it with another such device in Europe and same
thing at the Lufthansa check-in counter, the weight was right on the money.

https://www.walmart.com/ip/Neiko-Bea...l13=&veh= sem

You know for $18 a torque wrench isn't a bank breaking tool.


However, it does not have such an accurate digital display as my
solution :-)

But does it need it? If I recall the Octalink was tightened to 35 - 50
Nm... that is a pretty wide range isn't it? Does one need a digital
readout and an magnifying glass to get it right?


As I said it doesn't need it. All I said is that the luggage scale
solution is way more accurate than the average consumer-grade torque
wrench and, therefore, an adequate tool to gauge torque. It does take
two extra seconds to slip the strap over and press the button but that
much time I've got.

WhenI started cycling again in 2013 I had to buy Shimano sockets and all
that stuff. I just don't want more stuff in my already full tool cabinet
unless there is no other way. For torqueing there clearly is another way
to get by with what I've already got. It's easy.

--
Regards, Joerg

http://www.analogconsultants.com/

On 2017-08-26 13:30, jbeattie wrote:
On Saturday, August 26, 2017 at 1:04:00 PM UTC-7, AMuzi wrote:
On 8/26/2017 12:20 PM, jbeattie wrote:
On Saturday, August 26, 2017 at 8:26:38 AM UTC-7, Frank Krygowski wrote:
On 8/26/2017 10:55 AM, Joerg wrote:
On 2017-08-26 07:17, wrote:
On Friday, August 25, 2017 at 12:50:12 PM UTC-7, Joerg wrote:


[...]

 But you can use a rock and a nail -- but make sure its an old square
nail and the rock has a high feldspar content. You'll know when its
up to torque when the rock starts breaking apart -- and an owl passes
across the moon, and the great spirit sends you a signal. Or you
could get a torque wrench.


I like multi-purpose tools :-)

https://www.amazon.co.uk/Portable-Ha.../dp/B00C68JD3Y


I was surprised how accurate those are. Weighed a suitcase at 49.0lbs.
Lifted it onto the baggage check scales at UAL, with that white-knuckle
feel that it might be over. Nope, their display also showed 49.0lbs. On
the way back I weighed it with another such device in Europe and same
thing at the Lufthansa check-in counter, the weight was right on the
money.

https://www.walmart.com/ip/Neiko-Bea...l13=&veh= sem


You know for $18 a torque wrench isn't a bank breaking tool.


However, it does not have such an accurate digital display as my
solution :-)

There are people who think that anything with a digital display must be
more accurate than anything with an analog display. Those people are
simply wrong. Accuracy is affected by the design of the entire system,
not merely the display.

Example: I once dissected a bathroom scale that had a digital display.
That one had precisely the same collection of levers and springs found
in an analog bathroom scale; but instead of rotating a disk printed with
numbers, it rotated a sort of encoder wheel. The electronics read the
encoder and flashed the LED numerals. It was all for show, with perhaps
a slight benefit regarding reading numbers in dim light. Or perhaps
helping people who can't interpolate using the little marks between 210
and 215.

In the case of your kludge: The digital luggage scale may use a simple
spring as a transducer, just as that bath scale did, and be no more
accurate than a spring scale. If instead it has a system based on
strain gages or other such technology, it may or may not have proper
temperature compensation. If it actually is very accurate, your kludge
also depends on your positioning of the scale on your wrench or other
lever arm, and I'd suspect your precision in placing it at exactly 8"
(or wherever) is less than stellar. And if you do place it at precisely
the right location, you also need to pull precisely perpendicular to the
lever arm. Of course, as the lever arm rotates, you must maintain that
perpendicularity, and your eyeballs may not be as good at that as you
probably believe.

OTOH, for a bottom bracket retainer, the torque really isn't all that
critical. Rather than fuss around with a weird kludge, I'd either judge
the tightness by hand, or do what I actually did - which was just buy a
blasted torque wrench, and do it nearly 50 years ago.

You do need to make sure the 8mm bolt on an Octalink crank is tight enough because those things wallow. It's not a job you should do with a 4-6" hex wrench and a luggage scale -- or a rock, nail or what-have-you.

-- Jay Beattie.


You're using the wrong kind of nail. The good ones come out
of wooden fenceposts in Cameron Park.

Joerg's bike shop in Cameron Park: https://www.youtube.com/watch?v=1WqazleR3FE


Nah, this is how it's done :-)

https://www.youtube.com/watch?v=dEkOT3IngMQ

--
Regards, Joerg

http://www.analogconsultants.com/