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Brass Nipples!
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Discussion Starter #1
How high are you wheelbuilders tensioning your wheels?

I usualy try to get 125-150 kg. of force on the higher tension side. Jobst Brandt describes a method of tenisoning a wheel to the point of failure, then backing off and retensioning to just below that value. I did that a few years ago with a Bongrager Maverick rim (failed at just over 150 kg.), but I haven't repeated the procedure with other rims I use. Road wheels fail (suddenly go out of true as I'm tensioning them) occasionally betwen 125 and 150 kg, but I don't make it a point of going to failure routinely.

Any interest in starting a database of maximum tension values for various rims?
 

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I have never built or measured my wheels with a tension measuring device.

I use the Jobst Brandt method, though I was taught it before I heard of his book, and look for the point that the rim starts to act strangly. I found that prior to failure the rim will start to wander and the stress relieving will cause it to move aroud a lot. I finish up here and let the wheel sit for 24-48 hrs before it get ridden so as to settle it. When building with the up to failure method this settling period is vital or the wheel will keep wandering all over the place, I have also foung that wheels built with PG spoke don't settle in the same way (less creep?) and I don't use them.
 

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Code Burr
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Bob the Wheelbuilder said:
How high are you wheelbuilders tensioning your wheels?

I usualy try to get 125-150 kg. of force on the higher tension side. Jobst Brandt describes a method of tenisoning a wheel to the point of failure, then backing off and retensioning to just below that value. I did that a few years ago with a Bongrager Maverick rim (failed at just over 150 kg.), but I haven't repeated the procedure with other rims I use. Road wheels fail (suddenly go out of true as I'm tensioning them) occasionally betwen 125 and 150 kg, but I don't make it a point of going to failure routinely.

Any interest in starting a database of maximum tension values for various rims?
I think you are pushing the limit past 120. Thats where I usually start to break nipples.
Any reason why you run them so high?
 

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Brass Nipples!
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Discussion Starter #4 (Edited)
Why so tight

Jobst Brandt says that a properly built wheel's spokes never get tighter when it's ridden. It's hard for me to intuit this, but he says that a loaded wheel's top facing spokes don't get tighter as it rolls, the bottom ones get looser. He gives the finite element analysis to back this up in his book. Once the wheel is built, it sees maximum tension in its static state, so riding won't ever break spokes from increasing tension.

If there isn't enough tension, spokes can get slack, and that's when movement of the spokes occurs, usually at the spoke elbows and nipples. this repeated stress is the usual cause for spoke failure. The tighter the wheel is built, the less potential for movement of its components and the less chance of failure. Butted spokes can actually increase the wheels durability because the flexing occurs along a wider area of the spoke instead of being concentrated at the ends as with a straight gauge spoke.

The other reason to build the short side so tight, is that the other side of the wheel (nondrive on rear wheels, drive side on front discs) will be quite a bit looser. Using a symmetric rim on a 130 mm spaced road wheel, it's hard to get the nondrive rear spokes tight at all, even with the drive side to 125 plus kg. That's why tandem and heavy touring bikes use wider hubs in order to reduce or eliminate rear wheel dish. If a person is having a custom road bike built, I'd recommend having the rear spaced for mountain (135 mm) hubs as the resulting wheels will be quite a bit stronger. If you do this, swapping wheels with someone with a traditional wheel will be out of the question, however.

On a symmetric front wheel, 100 kg. of force is probably adequate, but you can go tighter to the point of failure as described in my first post if desired. The time when maximum tension helps the most is when the wheel is not symmetrical.

All the tacoed front wheels I've seen (none of which I've built, by the way) have had relatively loose spokes. I imagine that unequal tension could contribute to this problem as well.

This is why I recommend brass nipples for the higher tension side of the wheel. It's very hard to get an aluminum nipple to hold up to that kind of tension.
 

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High tension

I tend to build a lot of wheels with Al nipples (could have something to do with being a weightweenie...) and have found that I can build them on the tight side successfully if I use a good lubricant, a good spoke tool (DT) and build the tight side first. By this I mean I lace the wheel and then procede to tension the tighter side the to point I am happy with it, and its round and true. I then bring the wheel back to the correct dish using the spokes that will be remaining at the lower tension, and if done well - it took me a few attempts to get it right at first - The wheel comes to dish and remains straight and round.
 

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Brass Nipples!
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Discussion Starter #6
I agree, good tip.

When I use the same type of nipples on both sides of the wheel I also tension the tight side first, usually truing it to a position about 3-5 mm off center toward the shorter spokes. I then swing it over with the looser spokes, 1/4 - 1/2 turn at a time all around the wheel. That is a great way to get a little more tension without destroying alloy nipples on the tight side.

I use a Spokey spoke wrench. It bites on all 4 sides of the nipple like a DT, but it's a lot cheaper. Some day I'd like to get the DT, hear they're the best.
 

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featherweight clydesdale
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Bob the Wheelbuilder said:
How high are you wheelbuilders tensioning your wheels?

I usualy try to get 125-150 kg. of force on the higher tension side. Jobst Brandt describes a method of tenisoning a wheel to the point of failure, then backing off and retensioning to just below that value. I did that a few years ago with a Bongrager Maverick rim (failed at just over 150 kg.), but I haven't repeated the procedure with other rims I use. Road wheels fail (suddenly go out of true as I'm tensioning them) occasionally betwen 125 and 150 kg, but I don't make it a point of going to failure routinely.

Any interest in starting a database of maximum tension values for various rims?
As a non professional, I have a hard time building them for what I can buy them assembled for. That said, I have built and rebuilt a few and haven't paid for a shop to true a wheel in over 10 years. Loving the tension meter!!

An amazing lack of responce to this thread. Is this proprietary info?? A database would be great. Anyhow...

I checked the tension on a Velocity Dyad / King /DT Supercomp / Alloy nip build I got not long ago from a popular custom builder. The rear drive side was an amazing 164 kg and the disk front was 140 kg. I don't think I'll ever have to touch these wheels.

A previous Mavic T-520 build from an LBS had sub 90kg tension and had constant problems. I've got the rear drive up to 115kg and having much better success.
 

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Most of the wheels I've built, road and xc mtb, are tensioned to about 100 for the front and maybe 115-120 for the drive side rear.

I'd like to get them a bit tighter to increase lateral stiffness, but most of the rims are Mavics and I've seen too many cracked nipple holes...from spokes possibly being too tight(?). I contacted Mavic, they told me that I was probably going too fast for the conditions...yeah, right :rolleyes:

It would be good to know what spoke tension the rim mfg'ers recommend.
 

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Code Burr
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I've found that 100-110 works perfect for me on the xc rims I use and build. Theres no reason 120+ wont work for you but I think that pulls a little too much for the skinnier/liter rims and ends up stressing them. This is my opinion so take it for what its worth, but heres some specs, maybe Bianchi or Ventanarama can offer there suggestions, then again the more info they offer up the less job security remains. /jk

Dt Swiss XR4.1d 100-110kgf w 14/15 spokes
Mavic 819d 105-115kgf w 14/15s
Mavic f519 110-115kgf w 14/15's
Mavic D321 115-120kgf w 14 spks

I seem to remember Calvin from park tools saying something about tension limits.
http://forums.mtbr.com/showthread.php?t=35906
 
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