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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 05-01-08, 05:42 PM   #1
rwgreenberg
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Crank torqueing advice please

Hi all. Iíve been trying to do more and more in the way of basic bike maintenance over the last year. I feel comfortable with adjusting the derailleurs, brakes and replacing tubesÖall essential do-it-yourself jobs. I recently bought a fairly expensive folding bike (Bike Friday New World Tourist) and did some more reading about the things one should do after riding a new bike for a couple of months. Of course I already had the derailleur adjustments down (which go out of adjustment a lot when the bike is new).

I decided to buy a Park beam torque wrench to torque the cranks, as this seems to be on the list of things to do early on (and I thought Ė how hard can this be?). I practiced a few times on an older less expensive mountain bike. First I undid the bolt, greased it, and then tried to torque it to specs (40nm). I found it quite difficult to read the gauge, pull on the wrench, hold the crank in place, and keep the bolt moving until the torque was reached. After going through this procedure a few times, I came to the conclusion that I really did not feel all that comfortable tackling the expensive new bike.

So here are my questions:

Is it really that important to go through this crank torqueing routine (they donít feel loose at all)?

Should I buy a click-type torque wrench and will this make the process easier for a klutz like me? And if so, which one is recommended?

And, on another note, should I tackle the adjustment of my Chris King headset? I read a bit about this, and it does not look easy!

Anyway, any advice on the above would be most appreciated. Rich
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Old 05-01-08, 05:54 PM   #2
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I also, have a NWT. As for the proper torque, all bolts and nuts have a specified torque. That does not mean tight and a half turn more. After you have done some bolt tightening to the proper torque you will know when you have it within the specs. As for a click type torque wrench, A lot easier to use as all you do is set the torque desired on the wrench and tighten until the wrench clicks. Is it worth the expense? That is your call. As a retire aircraft mechanic I prefer the click type. That comes form years of using one.

The head set adjustment is rather a simple process. Try doing the procedure in Park Tools web site.
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Old 05-01-08, 08:27 PM   #3
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I made my own torque wrench using a steel bar and a dial type fisherman's scale that reads 0 to 50 pounds. The nominal distance between the scale and the tool is ten inches. The dial is easy to read. 35 pounds is 350 inch pounds, which is about what my bikes requires for the bolts that hold the cranks on the bottom bracket shaft. I mentioned the nominal length of the steel bar because I weighed something of a known value and found the scale read six percent light. I shortened the distance by six percent to compensate. The cost of my wrench was about $5. Park Tool's web site has a conversion table for Newton meters to inch pounds, etc.

On adjusting your headset, I assume you are talking about putting some tension on the screw in the stearer cap before tightening the stem bolts. It is really pretty simple. Perhaps I do not understand your question.

I do like to torque to specs wherever specs are given. There have been a number of threads on this during the last year. Some use a torque wrench. Some insist they can do it by feel after gaining some experience.
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Old 05-01-08, 09:40 PM   #4
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It's important to keep your crank arms tight and properly torqued. If they aren't tight enough, you can fairly easily damage them. Because they are aluminum, the spindle of your BB can "eat" into them from the hammering resulting from a loose crank arm.

Whether you use a beam type or clicker wrench, it really shouldn't be that hard. As both wheels are on the ground, I just grab onto a pedal and tighten 'er up, working 180 degrees against myself, until she meets spec. Perhaps you could have a friend help hold the crank arm as you tighten. At any rate, don't neglect this chore, you could ruin your crank assembly.
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Old 05-02-08, 10:35 AM   #5
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speaking of torque. this thread got me looking for a torquing guide which i found on the park site:

http://www.parktool.com/repair/readhowto.asp?id=88
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Old 05-02-08, 02:07 PM   #6
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I am totally confused.

Why would you go to expense of buying a torque wrench and then try to rationalize not using it?
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Old 05-02-08, 05:47 PM   #7
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Quote:
Originally Posted by DMF View Post
I am totally confused.

Why would you go to expense of buying a torque wrench and then try to rationalize not using it?
I think the expression is, "I'm chickening out."
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