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Old 07-30-08, 06:03 PM   #1
BikingGrad80
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TM-1 says spokes too tense?

I finally decided to buy a tensiometer. I was surprised when it told me that I build my wheels too tight. It says my average is 120-137 kgf front and rear drive side. Should I be concerned? I know the recommended max tension is 100-110.

These include
Bontrager Maverick to LX hubs
Open Pro Ultegra
Sun CR18 to old 105.
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Old 07-30-08, 06:14 PM   #2
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I get some really high numbers for double butted spokes. My driveside rear Revolution spokes show to be 157 kgf. After several years of riding on these wheels I've had no problems.

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Old 07-30-08, 06:42 PM   #3
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My spokes are plain 2.0 straight gage 32-36 3X. I always though as strong as possible without rounding the nipples and nice ping from the spokes when plucked.
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Old 07-30-08, 07:04 PM   #4
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You'll know they're too tight when you develop cracks in the rim near the spoke holes.
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Old 07-30-08, 07:13 PM   #5
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Originally Posted by BikingGrad80 View Post
I finally decided to buy a tensiometer. I was surprised when it told me that I build my wheels too tight. It says my average is 120-137 kgf front and rear drive side. Should I be concerned? I know the recommended max tension is 100-110.

These include
Bontrager Maverick to LX hubs
Open Pro Ultegra
Sun CR18 to old 105.
The 100-110 kgf seems way too low for me regarding 9-10 speed DS rear wheels. I never use less than 120 kgf on my rims (mostly Mavic CXP 33). Around 125-130 kgf are my target. A wheelset I build before I got my TM-1 was tensionend more than +140 kgf. The flange on my Ultegra hub broke after a year or so, but there were no problems with the rim even though it's official recommended tension is 100-110 kgf.
The hub had experienced one rim destroying crash which may have weakend it. I need the high tension because I am a heavy rider that sometimes carry a lot of heavy stuff in my panniers.
I don't think that the 100-110 kgf. number reflects any real world limit since e.g. all Mavic rims uses that number. It seems strange that so many different rims should have the same max limitation.

Resistance isn't a good measure of absolute tension since good lubrication may reduce resistance. I have temporarely "tacoed" a CXP 33 rim without trouble. (I estimated that this must be around 150 kgf).

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Old 07-30-08, 08:07 PM   #6
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I think I'll leave the Open Pro's at 120 but the Bontragers are prone to cracking I think I'll back them off 1/2 turn or so.
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Old 07-31-08, 02:19 PM   #7
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I think I'll leave the Open Pro's at 120 but the Bontragers are prone to cracking I think I'll back them off 1/2 turn or so.
1/2 turn is an awful lot on a spoke nipple, probably too much.
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Old 07-31-08, 02:40 PM   #8
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Make sure you're using the correct conversion-factor for the spokes you have. The max-tension actually varies from rim-to-rim based upon the design. Look up the manufacturer's specs and make sure your wheels are at the high-end of the range.

On the Bontrager, which are crack-prone, you'd want to go slightly lower. You'll be sacrificing some spoke-durability and overall wheel-strength in order to balance it with rim-strength.
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Old 07-31-08, 03:05 PM   #9
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+1 to double-checking the conversion and the rim mfgr's recommendations.

I tried to take my Aerohead OC to 120kgf and it went all wonky-taco on me. I backed it off 1/8 turn all the way around, and the wheel has been perfect for 4k miles so far. So, you don't always have to wait for the rim cracks to know you've gone too high on the tension
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