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Old 05-12-10, 06:24 AM   #1
kissTheApex
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Determining Spoke Tension

I'm sure this is a much discussed issue, but a quick search did not turn up many results that could be useful to me. I am going to be building my first wheel set soon and finally I found a co-op that has the truing stand, tension meter and dishing gauge somewhat close to home.

My build consists of Kinlin XR300 rims (24F/28R), ultegra hubs, DT Comp spokes and brass nipples. I will be lacing all 2x. I am currently 183lbs if that makes a difference. The results that I can find online points to 100 kgf front and 125 kgf rear. Is this appropriate? How is the proper tension for a wheel is determined?

And what is allowable/desired range of deviation from the determined force on spokes? I believe in the process of truing, some spokes will have less, some will have more tension but when is one to stop messing with that particular spoke lest it goes above or below the desired deviation from set kgf for that wheel.

I hope I made myself coherent. I'm a very inexperienced mechanic when it comes to bikes and I may not be using the correct terms. So apologies in advance.

Thanks,
Ihsan
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Old 05-12-10, 08:12 AM   #2
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100-103 kgf front should be enough...

110-115 kgf rear drive side should be enough...try not to go past 120 kgf on average...

Stress relieving via hard squeeze of parallel spokes for two rotations after each tension cycle is extremely important. Dish and trueness should hold after final stress relief action...

...ride..get back to us...

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Old 05-12-10, 09:05 AM   #3
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Use the DT spoke calculator website if you're a novice. Measure the actual ERD of the rim at four places and use the average number (should be within +/-1.5mm with a good rim). Gradually crank up the spoke tension on the cassette side so that the end of the spoke with the highest tension is within 0.7mm from the end of the nipple (DT comp 2.0mm). It's a good idea to overshoot by 1/16-1/8 of a turn when tighening/losening a spoke, and recover by the same amount in the final stage of wheelbuilding. This will remove most of the spoke "twist".

Do not overtorque (spoke extends beyond the end of the nipple). If the rim is of good quality, then all the spokes should engage the nipples by the same number of turn, plus/minus 1/2 to 3/4 turn with the finish product.

Take the wheel out lay it on one side. Use your hands to apply about 100lbf total on opposite side of the rim. Work around the rim at each spoke (28x for 28h hub). Do the same to the other side of the wheel.

Another advanced technique is to true the wheel at a higher preload (cassette side) by 1/2 to 1 turn, then backoff by the same amount for the final product.

In general, a wheel that's true to within +/- 1mm will have more sloppy spoke tension than one that's true to within +/-0.1mm (assuming the rim is of good quality).
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Old 05-12-10, 11:31 AM   #4
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The topic is also covered in the often-recommended book from http://www.wheelpro.co.uk/wheelbuilding/book.php. If you're building a wheel, you may find the advice in it quite useful for its price of little over $10.

One thing, for instance, is that tension meters have an accuracy of about +-10% at best - don't take their readings as absolute values and don't fret over small differences between them and the "recommended" values. Even wheel manufacturers have a wider range they recommend. There's no magic formula to determine X as the optimum tension but more a matter of exclusion: values too low and too high are excluded (because they cause problems) so what's left in between them becomes the recommended range.

Likewise, there is no precise, particular threshold of deviation from the recommended value to tell you "when stop to stop messing with that particular spoke". The real world is continuous, we humans prefer clear thresholds, but they are a matter of convention.

Good luck with the wheel!
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Old 05-12-10, 11:35 AM   #5
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I would aim for 110kgf all around. Kinlin XR-300 rims are surprisingly strong for their weight.
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Old 05-12-10, 01:14 PM   #6
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I'd plan to go higher than 120 kgf on the drive side rear if the hub is 8, 9, or 10 speed. The extreme dish offset requires high tension on the drive side in order to center the rim and at the same time get enough tension in the non-drive side to avoid excess spoke flexure and broken spokes.
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Old 05-12-10, 02:01 PM   #7
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Quote:
Originally Posted by Al1943 View Post
I'd plan to go higher than 120 kgf on the drive side rear if the hub is 8, 9, or 10 speed. The extreme dish offset requires high tension on the drive side in order to center the rim and at the same time get enough tension in the non-drive side to avoid excess spoke flexure and broken spokes.
I would go with DT revo spokes for NDS instead of going higher than 120kgf on the drive side of kinlin rims.
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Old 05-12-10, 03:57 PM   #8
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I second the recommendation for Roger Musson's book "The Professional Guide to Wheel Building" http://www.wheelpro.co.uk. An invaluable source of info. It is an E-book so available for download. Sheldon Brown is also good. He got me started. http://sheldonbrown.com/wheelbuild.html. Also realize that it's a lot science and a lot art and therefore there are a lot of differences of opinion as to what/how to do it. Read and listen to the pros. A lot of them are right here. But many of the issues/questions you have will not result in a unified consistent answer.
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Old 05-13-10, 04:57 AM   #9
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Thanks for all the replies. I'll get the Roger Musson's book to read while building.
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Old 05-13-10, 09:40 AM   #10
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The 4 resources in my wheel building library are (in no particular order)

Sheldon Brown (well, not really in my library, but online)
The Bicycle Wheel by Jobst Brandt
The Roger Musson pdf (listed above)
The Art of Wheelbuilding, by Gerd Schraener (this seems be be recently ouit of print, as prices online are skyrocketing)
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