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What do I need to know about buying a torque wrench
#1
Hi all,

I'm planning on building myself a bicycle with a carbon frame. I know I need a torque wrench, and I know it should have both standard and metric measurements, but what else do I need to know?

I'm thinking of buying one of these: Craftsman Microtork® Torque Wrench, 25-250 in. lbs., 3/8 in. Drive
Should do that everything I need? Do I need to get some attachments? Thanks.
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#2
Hello Gary,

Yes that one should do as I know Craftsman Tools come with lifetime warranty and if it breaks well you can always take it back and get a new one. Smile Just remember that when you add extensions bars you have to take in consideration the length. I don't remember what the math is, but I do believe it comes with the chart. I would say that is a very nice torque wrench. It is always a pleasure to build your ride from frame up too. Great luck to you.

Bill
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
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#3
Will that fit everything I need to use it for, or do I need to buy attachments for different sizes?

Thanks Bill.
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#4
You'll definitely need bits for 3,4,5mm (allen? inside hex) and also torx bits. I'd try to get a mid range quality set of bits for hex, allen and torx in different sizes, if you don't have one already. 3/8" drive is common, so this should be easy. (The sizes mentioned assume that bikes in your part of the world are also built using metric screws... maybe somebody else can comment on that? I think that it is metric everywhere, at least judging from tool suggestions e.g. by Sheldon Brown).

Cassettes are tightened with 30-50Nm (260-430 in. lbs) (Shimano specs), so you either guesstimate or get a torque wrench from some car part dealer, they should be quite inexpensive.
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#5
The beam-type wrench that Sears/OSH sells is a reasonable way to go. I have found it to be reliable and repeatable. Biggest issue for me with that wrench is that you have to be able to see the needle while torquing. The electronic wrenches "beep" so they can be used in orientations that make the needle hard to see. I would suggest you avoid the "breakdown" or "micrometer" style wrenches (Sears or Harbor Freight) with the twist-grip as the affordable ones are not very repeatable and require resetting to zero to remain accurate. If you can afford to build a full carbon bike you might consider a digital "split beam" wrench like the PREC2FR100F sold by Amazon and others. Strain gauge-based wrenches are great--but $$$. Neither the split beam nor strain gauge types require resetting to zero remain accurate.
...j
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#6
Interesting, as I never heard of the resetting to Zero in all my time of using torque wrenches. I do have a certification in Truck Mechanics (Diesel/Gasoline). I have met and talked shop with mechanics from a lot of areas and none of them said anything about resetting to Zero. Guess it would make sense though. Thanks for the tip. Something many do not know is if you add like a 6inch extension it changes the math.




(01-13-2010, 05:42 PM)j beede Wrote:  The beam-type wrench that Sears/OSH sells is a reasonable way to go. I have found it to be reliable and repeatable. Biggest issue for me with that wrench is that you have to be able to see the needle while torquing. The electronic wrenches "beep" so they can be used in orientations that make the needle hard to see. I would suggest you avoid the "breakdown" or "micrometer" style wrenches (Sears or Harbor Freight) with the twist-grip as the affordable ones are not very repeatable and require resetting to zero to remain accurate. If you can afford to build a full carbon bike you might consider a digital "split beam" wrench like the PREC2FR100F sold by Amazon and others. Strain gauge-based wrenches are great--but $$$. Neither the split beam nor strain gauge types require resetting to zero remain accurate.
...j
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
  Reply
#7
Hi Gary,

It's a nice TR, but I'm going to be the odd-one-out here, as I believe it has too much emphasis on the stronger side of life. You wouldn't be able to use it on stems or handlebars as 15lbs is the recommended torque.

Keep looking.

Keith
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#8
(01-15-2010, 01:44 PM)batch2103 Wrote:  Hi Gary,

It's a nice TR, but I'm going to be the odd-one-out here, as I believe it has too much emphasis on the stronger side of life. You wouldn't be able to use it on stems or handlebars as 15lbs is the recommended torque.

Keep looking.

Keith

This is always an issue with torque wrenches--big enough for heavy torque means the range doesn't go down far enough for the light stuff. Sears sells a strain gauge wrench with a range of 10-200 ft-lbs for about $219. I have been using the $25 beam wrench from Sears in the 10-50 ft-lb range and have been pretty pleased with the results.
...j
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#9
Conversions:

http://www.pitt.edu/~rsup/touqueconv.html
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#10
In case anyone has any comments or feedback, the two torque wrenches I'm looking at (on amazon.com) are the GearWrench 85052 3/8-Inch Drive 10-100 Feet/Pound Micrometer Torque Wrench and the GearWrench 85050 1/4-Inch Drive 30-200 Inch/Pound Micrometer Torque Wrench. It looks to me like that will cover the range of 30 inch pounds to 1200 inch pounds, or 2.5 foot pounds to 100 foot pounds. Both have a high user review average. But they are a bit pricey.
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#11
They look pretty durable and nice. You get free shipping though Smile .
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
  Reply
#12
(11-09-2009, 08:26 PM)Bill Wrote:  . . .Yes that one should do as I know Craftsman Tools come with lifetime warranty and if it breaks well you can always take it back and get a new one. Smile

Just a slight correction. I recently took a 3/8" ratchet back to Sears because the ratchet mechanism was slipping. No doubt a common problem and I might have been able to just buy a repair kit. But the salesperson did NOT give me a new one. They gave me a rebuilt one. (icky) Smile

That might not be the case with a torque wrench though. I wasn't allowed to look inside their rebuilt tools drawer below the cash register to see if they had any of those. Smile

Steve
Junkyard Tools rescued from the junkyard!
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#13
No kidding? That is rather weird. Although it has been like 15-20yrs since I last replaced a Craftsman tool they always gave me a new one. Again that was a long time ago when they were lifetime guarantee and replaced with new no questions asked.
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
  Reply
#14
Yeah, competitiveness and the current economy probably has a lot to do with it. Sad

I'm sure if you break a socket or combination wrench they would give you a new one. There's nothing to fix on those when they break.

Steve
Junkyard Tools rescued from the junkyard!
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#15
Nice
conversion chart lumpy.

AS per batch2103 note 15 ft lbs X 12 + 180 inch lbs. This works both ways . Divide inch lbs by 12 to get ft lbs.

I have two sears beam wrenches. Good value.They work well for where I need to use them . I just use them on stressed items where specific torque and even across is important. Most of my work by now I do by hand with a small wrench and with my fingertips.When I started in school of hard knocks I broke a few things. Like the crank pin someone cranked too much seen on this list.

Get a TW that has most of your figures starting about 1/4 into the scale and 1/4 before end. The middle range is the most accurate.



Most pros use the clicker wrenches. More expensive but good. They do need to be warmed up before using on sensitive bits by putting a bolt in a vise and using the wrench on it at preset setting to make sure it clicks. They can also be calibrated at a certified shop.

A simple test is to lock the socket end in a vise and hang a weight in the center of the handle.

I have much more info somewhere besides my head. :-)))
Never Give Up!!!
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#16
For the inquiring minds out there here are some links from my other bike list.:-)))

http://bmwmotorcycletech.info/torquespecs&problems.htm

http://home.jtan.com/~joe/KIAT/kiat_3.htm
Never Give Up!!!
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#17
I guess I am old school, but I rarely use a torque wrench on anything. Over-torquing has never been a problem for me. I do own an old Sears beam wrench (ft-lbs) as well. In my years of experience, I have found it is better not used unless it is critical such as cylinder head bolts, relican rods, etc. Smile

Steve
Junkyard Tools rescued from the junkyard!
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#18
Having the proper torque is critical in carbon-frames though. Not so much on other types of frames. But you definitely don't want your fork breaking on a ride.

I have one of the basic torque wrenches from Sears, the non-digital kind. Does well for me.
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#19
Yup, I can see where a carbon-fiber frame would require a highly-accurate torque wrench. Like I said, I'm old school. The newest bike I own is a 1991 Raleigh Tangent MTB, cro-mo frame.

Steve
Junkyard Tools rescued from the junkyard!
  Reply
#20
Never thought about that, always thought torque wrenches were made to remind the mechanic to tighten every bolt lol until I got older.
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
  Reply


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