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Question about torque on components..?

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Question about torque on components..?

Old 06-10-07, 07:34 PM
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pinetreeforest1
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Question about torque on components..?

Hi there. During my ride today I noticed a slight clicking when force was applied on the right pedal. I just lubed up the pedal, cleaned it out, and then decided to tighten the chainring bolts. According to my manual, the torque that should be applied to these 5 chainring bolts is 70-90 lbs. per inch. I'm a bit worried doing this by hand, because I don't want to over tighten with my hand and damage the crank. I just tightened them, and wonder if I should loosen them, then re-tighten. Should I get a torque wrench for sensitive items like this? BTW, it's a Bontrager Isis double crankset.
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Old 06-10-07, 08:44 PM
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You should buy a torque wrench. Get one that reads in inch pounds not foot pounds unless your a good mechanic and confident you can use a foot pound wrench well enough to figure it out in inches. Also don't buy one of those click type of torque wrenchs because their not always accurate, instead buy a beam style torque wrench, but be careful about the beam type because one drop could damage the beam.

Park sells a decent one for fairly cheap that you can buy at any LBS; see: http://www.parktool.com/products/det...13&item=TW%2D2

Or you can go down to a tool store and see if you can find one, problem is though that most tool stores sell foot pound and not inch pound torque wrenches.

Don't forget when you torque things down you do it in a star pattern like you would installing a wheel on your car, you then set the torque wrench about 30 pounds LESS then the recommended torque then you work around in the star fashion, then increase the torque 15 more pounds and repeat tightening them in a star pattern, then finally increase another 15 pounds (to the actual recommended torque value) and repeat.

But if their already tight what makes you think it's the chainring? It could be the pedal, it could be your shoe, or it could be the bottom bracket.

Last edited by froze; 06-10-07 at 08:49 PM.
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Old 06-11-07, 08:54 AM
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I made my own inch-pound torque wrench from a steel bar and a dial indicator fisherman's scale. I saw a torque wrench at a local hardware store. Yes, it reads inch-pounds, but markings are graduated at intervals of 50 inch-pounds! The fisherman's scale is graduated so that it reads to the nearest five inch-pounds.

I used a ten inch steel bar heavy enough not to flex. I made one end so I can slip my standard hex key (Allen) wrenches into it. The scale attaches ten inches down the bar's length. A five pound pull is 50 inch-pounds.

I weighed something of a known weight and found the scale weighed about six percent light, which would have resulted in too much torque, so I shortened the ten inches by six percent.

If you buy a torque wrench, you have the initial cost of $20 to $40. Then you also need to buy hex key sockets. That is another $20. My wrench cost me $5 in materials.

I posted this before. One fellow said he has been using a similar home made wrench for years. Another fellow basically told me I surely used time more valuable than the money I saved. I once had a response that said it was not the right tool because it did not come from a commercial concern. It would have been nice if they could just have said, "Congratulations. Good idea."
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Old 06-11-07, 09:46 PM
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Originally Posted by Astaroth
If your loooking for a Inch pound torque wrench ANY auto supply that carries tools will have one or 2.
Problem with auto supply places is that they usually only carry 0 to 60 inch pound torque wrenchs and none that go above 60 unless they start at 100. There are some real expensive dial units you can get that some auto parts place might carry but those will run you over $150; although the accuracy is better then a beam type you don't have a need for that kind of percision.
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Old 06-11-07, 10:13 PM
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Originally Posted by Astaroth
As i do have 5 torque wrenches in the .25,.375 & .5 variety.

I wouldn't recommend one of these el cheapos but here is an example...
http://www.amazon.com/gp/product/B00...d_i=B000I7ZDN4
The one you showed is the click type and those are not as accurate as the beam type and they get less accurate as time goes on or if dropped. You can get the beam type for the same cost of a click type, it's the dial type that will set you back a few dollars. I have a dial type (use adapters to change it from 1/2 inch when needed) but it's for engine work and not for the bike.
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Old 06-12-07, 10:26 AM
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Originally Posted by froze
The one you showed is the click type and those are not as accurate as the beam type and they get less accurate as time goes on or if dropped.
I wish you'd stop repeating this misinformation. Neither type is inherently more accurate that the other. In fact, beam-type might be considered less accurate when you figure in the problems of trying to read them.

Besides, wrench accuracy is hardly the limiting factor in achieving a specified torque setting. The fasteners themselves vary all over the place. And look at the spec - the range is typically 20% - way beyond any potential variance of the wrench.

Beam-types are usually cheaper. Clickers are easier to use. That's about all the difference that matters.
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Old 06-12-07, 12:20 PM
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If you're worried that you may have overtightened the bolts already, I might consider replacing them.
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Old 06-12-07, 08:39 PM
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Originally Posted by DMF
I wish you'd stop repeating this misinformation. Neither type is inherently more accurate that the other. In fact, beam-type might be considered less accurate when you figure in the problems of trying to read them.

Besides, wrench accuracy is hardly the limiting factor in achieving a specified torque setting. The fasteners themselves vary all over the place. And look at the spec - the range is typically 20% - way beyond any potential variance of the wrench.

Beam-types are usually cheaper. Clickers are easier to use. That's about all the difference that matters.
I've known lot's of mechanics over the year in both auto and aircraft industry, and they all said the clickers are not as accurate as the beam type and especially the dial type. But both the clicker and the beam type have accuracy problems. Since you don't believe me, then read this from http://www.answers.com/topic/torque-wrench-2

"Differences between types:
Click type torque wrenches are more precise when properly calibrated—however the more complex mechanism can result in them losing calibration far quicker than the beam type, where there is little to no malfunction. Beam type torque wrenches are impossible to use in situations where the scale cannot be read—and these situations are common in automotive applications. The scale on a beam type wrench is prone to parallax error, as a result of the large distance between indicator arm and scale. There is also the issue of increased user error with the beam type—the torque has to be read off each and every use.

For the click type, when not in use, the force acting on the spring should be removed by setting the scale to 20% of full scale in order to maintain the spring's strength. Never set a micrometer style torque wrench to zero as the internal mechanism requires a small amount of tension in order to prevent tool failure due to unwarranted tip block rotation. If a micrometer tool is has been stored with the setting above 20% the tool should be set to 50% of full scale and exercised at least 5 times before being used. In the case of the beam type, there is no strain on the component that provides the reference force except when it is in use."

The following have useful information also about how to use a torque wrench as well as information in regards to you thinking I'm giving false information.

So see this: http://home.jtan.com/~joe/KIAT/kiat_3.htm

And this about all 3 different types: http://www.zediker.com/articles/torque.pdf
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Old 06-13-07, 10:41 PM
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Forget the Torque Wrench Calibrate your hand

In some industries it is considered acceptable practice (in the case where a torque wrench will not fit) to place a torque wrench in a vice, crank it at the same lever arm then go to your subject tool and fitting and torque to what you felt. Thoughts? I might not do this in the case of a soft aluminum nut on my Fox fork but in general....

Last edited by ericthehalfab; 06-14-07 at 09:34 AM.
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Old 06-14-07, 06:12 AM
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Originally Posted by ericthehalfab
In some industries it is considered acceptable practice (in the case where a torque wrench fit) to place a torque wrench in a vice, crank it at the same lever arm then go to your subject tool and fitting and torque to what you felt. Thoughts? I might not do this in the case of a soft aluminum nut on my Fox fork but in general....
That's just guessing at the torque basically. If you have torque wrench but have the wrong drive size, lets say you have a 1/2 drive torque wrench, but your only socket that fits your bolt your wanting to torque is for a 1/4 drive, you can buy an adapter that fits on the 1/2 inch drive and reduces to a 1/4 to fit the socket on.
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Old 06-14-07, 09:36 AM
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To clarify, "in places where a torque wrench will not fit", in confined spaces for example, not socket size...
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Old 06-14-07, 10:31 AM
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Originally Posted by froze
I've known lot's of mechanics over the year in both auto and aircraft industry, and they all said the clickers are not as accurate as the beam type and especially the dial type.
You kinda missed the point of my post. (No, it was not developed in the first sentence.)

Whether or not one type is more accurate, it's bad advice! Because:
  • user error (reading the scale) trumps any innate accuracy advantage;
  • bolt stretch and thus clamping force (what we're really after) corresponds quite poorly to applied torque - thread condition is a major factor;
  • no accuracy advantage is meaningful when the specified torque range is so much larger than the accuracy or precision of the instruments;
  • you're ignoring the convenience of clickers.

Imagine someone saying that one should buy tool A because it is accurate to .0005" while tool B is only accurate to .001". But the specification is .02". Don't you see the folly of that?
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Old 06-14-07, 08:10 PM
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Originally Posted by DMF
You kinda missed the point of my post. (No, it was not developed in the first sentence.)

Whether or not one type is more accurate, it's bad advice! Because:
  • user error (reading the scale) trumps any innate accuracy advantage;
  • bolt stretch and thus clamping force (what we're really after) corresponds quite poorly to applied torque - thread condition is a major factor;
  • no accuracy advantage is meaningful when the specified torque range is so much larger than the accuracy or precision of the instruments;
  • you're ignoring the convenience of clickers.

Imagine someone saying that one should buy tool A because it is accurate to .0005" while tool B is only accurate to .001". But the specification is .02". Don't you see the folly of that?
Lets take this one by one.

1) user error, I agree except for one thing, when will a user ever learn to use one if he's too afraid of errors? with this arguement it would be just better to give up and not buy one at all and pay someone who hopefully knows how to operate a torque wrench.

2) Bolt stretch...that's why the manufacture uses torque ratings. If your using the correct bolt recommended by the bike manufacture then (hopefully) when they bought the bolts they got the correct torque values from the bolt manufacture to be used for the specific use it was intended. This is one of those take it by faith the manufacture got it right and 99.999% of the time they do.

3) Not sure what your saying with that one. Assuming you meant that the bolt your going to torque has a far greater torque value then the instrument is able to accurately read, so what? That just means that the bolt is a better bolt then needed to do the job and you can't over torque it for your particular situation. OR, do you mean that the torque value of the bolt for your particular situation exceeds what the torque wrench is capable of reading to...then you have to use a different torque wrench with greater capacity.

4) I'm ignoring the convenience of clickers...Maybe I am, but I also know the faults of those as well as the beam type, and of the two the beam type tend to be a bit more accurate; see my web sites I provided in an earlier post. I also know that the dial torque wrenches are better then either the clickers or the beam jobs, but I also know that most of you guys on this forum don't work on your own car engines and thus have no need for an expensive dial torque wrench. Thus narrowering it down to the two cheapest type of torque wrench's you can get, the beam type is the best of the two for accuracy. Granted a clicker can be accurate but you need to go and get them calibrated if you really want to make sure its accurate and remains accurate over the years; the beam type will remain accurate without calibration as long the device isn't dropped and the unit gets damaged in some way, which will also screw up a clicker; problem with clickers when their damage it's not apparent whereas with a beam you can usually tell. You can get both clickers and beam types for about the same price and most of the time the bit more accurate beam type are a tad cheaper.

5) Imagine someone saying that one should buy tool A because it is accurate to .0005" while tool B is only accurate to .001". But the specification is .02". Don't you see the folly of that?

NO, I don't see the folly in that. If tool A is close to the same price as tool B then why not buy tool A? Don't you see the folly in buying a less accurate wrench when a more accurate one may only cost you $5 dollars more and in some cases with beam type it may even be cheaper to buy the more accurate one? Also with the more accurate wrench if you are off on your torque setting by a bit your going to closer to the right torque setting then the other guy who is off a bit using a less accurate gauge. Don't you see the folly in that?

Granted, I'm a bit anal, but having worked on my own engines for years when needed, I don't like having things go wrong after putting all together only to learn I have a head gasket leak or some other problem because I didn't use an accurate enough torque wrench. The dial type are actually very easy to use and very accurate but an overkill for use on bicycles; but the beam type that Park sells is cheap, easy to use because the scale is larger, and accurate enough for bicycles.
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Old 06-14-07, 08:59 PM
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By the way, I rented an inch pounds torque wrench today for $6. That's an option as well.
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Old 06-15-07, 10:44 AM
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I give up.
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Old 06-15-07, 10:42 PM
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Originally Posted by DMF
I give up.
Then hand over your wallet...NOW!
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Old 06-23-07, 02:14 AM
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Okay Pros,

Time for a poll.

#1 how many of us cyclists actually own torque wrenches? I guess less than 1%.

#2 Those that do own them how many actually use them? And I mean use them for every recommended torqe setting on your particular bike, fork, rear shock, components, etc. What probably half.

I bet the gorillas that put my bike together definitely didn't use a torque wrench based on: pedals, crank, and stem.

All the more reason to DIY (with a torque wrench), or insure your LBS uses torque wrenches. With many light weight components any over torquing will ruin them.
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Old 06-23-07, 06:48 AM
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I have one, a 1/2" drive beam wrench that I alwaus have to zero the pointer before I use it. It's the the most subjective tool I own. I did have a 3/8" drive click stop micrometer that is on permenant loan somewhere.

Anymore I just torque by feel. Most smaller diameter fasteners (< 10mm) I'm within 5% of target value.

No, I don't have carbon fiber.
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Old 06-23-07, 07:39 AM
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Originally Posted by froze
Then hand over your wallet...NOW!
It used to be such a nice forum, too -- the kind of forum where everybody knew everybody and you could leave your doors unlocked when you went to work.

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Old 06-23-07, 07:49 AM
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Originally Posted by ericthehalfab
#1 how many of us cyclists actually own torque wrenches? I guess less than 1%.
How many cyclists wrench to the extent that they could use a TW? Of those, what % actually use one? I'd place it considerably higher.
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Old 06-23-07, 08:36 AM
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I bought a beam torque wrench when I began to work on my first automobile. I am a believer in following torque specs. whenever they are available. I always use a torque wrench (homemade--see above) on my new bike. Most of the time that means torquing the bolt on the seat collar. Not much else gets loosened often. (The seat post is carbon and the bike frame is aluminum. Another post said these can develop an electrolysis that binds them together. They should be separated periodically to prevent this.)
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Old 06-23-07, 08:48 AM
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Electrolysis between carbon fiber and aluminum? CF isn't conductive, afaik.
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Old 06-23-07, 08:50 AM
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Torque wrenches are yet another of the many cycling-related topics that evoke almost religious fervor among those on either side.

I, too, use them (my 1/4" in-lb analog clicker, and my 1/2" drive ft-lb digital clicker) wherever there's a spec. I'm also mindful of using good quality, good condition fasteners (that meet the manufacturer's spec), and of using the appropriate lubricant/anti-seize (or dry application) on those fasteners.

I don't believe that I've come anywhere close to 'calibrating' my wrenching arm ... yet.

Maybe one day.
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Old 06-23-07, 09:44 AM
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I have a breakover torque wrench. After spending way too much for a custom dual crown for our tandem, I don't really want to jack it up by over-tightening the bolts. The builder was very specific about torque values, and since he machines stuff for NASA too, I'll take his word.
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Old 06-23-07, 11:51 AM
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Originally Posted by DMF
Electrolysis between carbon fiber and aluminum? CF isn't conductive, afaik.
The relevant information is in this quotation:
Galvanic corrosion between carbon and aluminum is an issue we have discussed here before, and to combat it, you either need to wrap the seatpost with a layer to shield it somehow from the aluminum (there are some letters below with suggestions about that), or you need to pull it out frequently (certainly after any ride in the rain), clean it, and re-grease it (or, as we have discussed here as well, to prevent seatpost slippage, re-coat it with carbon assembly paste, available from Tacx, Ritchey or FSA).
This is from an article by Lennard Zinn in Velonews. Click here for the article.
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