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Old 06-28-07, 12:44 PM   #1
rschoeck
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Seatpost torque? Please advise..

Hey all,

I am new to the mechanics forum, but I had a little trouble on an adjustment being the perfectionist I am. My friend's dad just gave me a Fizik Arione saddle and I was fitting it to my Felt 1.2 Carbon seat post. I was using a standard 5mm for the dual bolt attachment underneath and cranked it just firmly. How tight do you normally tighten these bolts? I don't have a torque wrench and really don't want to damage the post. I am pretty sure this area of the post is stronger than where the collar tightens. Any insight would be great! Thanks
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Old 06-28-07, 02:25 PM   #2
twobikes
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I also have a carbon fiber seat post and like to stay within recommended torque specifications. My bike is a Specialized. I was able to download some technical service bulletins from their web site, including one on carbon seat posts. It included torque specifications. In the case of my seatpost, the recommendations were 40 to 55 inch pounds. Somewhere I saw higher figures for another seat post. There is a chart of torque specifications available for download at the Park Tool website, but many of the figures are based on a particular manufacturer. Still, they give you a rough idea of where to start. You might check the web page for your bike's manufacturer for any technical service bulletins.

Even though I used the suggested torque, my seat post sometimes slipped downward while riding. I solved that by moving the mounting collar for a rear reflector down the seat post to sit directly above the seat tube and tightened it moderately. It provides enough assistance to keep the post from sliding.

Several times I have posted information about my homemade torque wrench. It works very well. It is a steel bar strong enough not to flex and a dial-indicator fisherman's scale. I made one end of the steel bar so it will receive my standard "L"-shaped Allen or hex keys. I checked the accuracy of the fisherman's scale and found it weighed six percent light, which would have resulted in too much torque. I shortened the distance of the bar by six percent from the nominal ten inches I had planned to compensate for the error. I also try to stay a little toward the low side of allowable range of torque, just to be safe. At a nominal ten inches in bar length, a five pound pull is 50 inch pounds.

Torque specifications always assume you put a drop of oil on the bolt before tightening.

And, my bike has an aluminum frame. I have read that aluminum and carbon can bind themselves together with moisture and time. One recommendation is to remove the seat post periodically and put it back into place. That calls for torquing it again.
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Old 06-28-07, 05:13 PM   #3
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Quote:
Originally Posted by rschoeck
Hey all,

I am new to the mechanics forum, but I had a little trouble on an adjustment being the perfectionist I am. My friend's dad just gave me a Fizik Arione saddle and I was fitting it to my Felt 1.2 Carbon seat post. I was using a standard 5mm for the dual bolt attachment underneath and cranked it just firmly. How tight do you normally tighten these bolts? I don't have a torque wrench and really don't want to damage the post. I am pretty sure this area of the post is stronger than where the collar tightens. Any insight would be great! Thanks
You're talking about the clamp that you attach the seat rails to, right, not the collar where the post goes into the frame's seat tube?
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Old 06-30-07, 12:34 PM   #4
rschoeck
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Yes Camilo, that is correct. It is where the clamp attaches to the rails. I just don't know how tight to torque it by hand.
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