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Old 07-21-10, 10:22 PM   #1
praveendv
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Clarification on wheel build!

A complete noob and taught a little from JB book! Please be generous.

I'm building a powertap wheel with CX ray+Kinlin.

In the processs, on tensioning all the spokes equally, used PT TM, I expected the wheel to be laterally and vertically trued but not dished. To my surprise, I find it neither. The spokes were tensioned adequately and stress relieved. I'm worried that either my rim is out of shape or spokes are not good. Am I missing something here?

I could not judge, if washers are required b/w spokes and hub flange. For this kind of build, are washers (on rim [Kinlin] and on flange) recommended or needed?

TIA.
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Old 07-21-10, 10:51 PM   #2
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There's an existing thread on this already...please do to that one and stay tuned...

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Old 07-21-10, 10:54 PM   #3
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http://www.bikeforums.net/showthread...aking.../page2


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Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
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Old 07-21-10, 10:54 PM   #4
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I'm a noob in tensioning wheels myself. I used the Park TM also and got your same result. In a perfect world, it should be laterally and vertically true, but it isn't. you will have to go back and true them. When it is true, use the Park TM and you'll find that there is a variance in tension from spoke to spoke. Were you able to get it true eventually?
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Old 07-22-10, 01:06 AM   #5
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mrrabbit: thanks for the info. That thread didn't show up on 'equal spoke tension true' search. I read it now and it is exactly what I'm trying to build but 2x. It seems to be answering to broken spoke causes which is not what I'm looking. I'll follow that thread for the wheel build.

531phile: I trued all the spokes to around 50kgf drive side and little less on non drive side. I got scared after what I found and stopped it. I have Mavic K E wheels and experimented on it. I found all spokes on drive side had exactly same tension, same with non drive side, which worried me more. I was wondering if it is the case at 50kgf it perhaps will be the same at ~100kgf, non equal tensioned spokes. That is wrong, right?
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Old 07-22-10, 03:38 AM   #6
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Quote:
Originally Posted by praveendv View Post
..In the processs, on tensioning all the spokes equally, used PT TM, I expected the wheel to be laterally and vertically trued but not dished. To my surprise, I find it neither. The spokes were tensioned adequately and stress relieved. I'm worried that either my rim is out of shape or spokes are not good. Am I missing something here?
Well, either you started with a rim that wasn't exactly round or true, with not exactly round being reasonably common. There will often be some sort of deviation at the rim joint. Or you missed the count when you first started threading the nipples on, it's easy enough to have that happen. Or whoever picked the spokes out for you accidentally grabbed a few from the wrong box.

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..I could not judge, if washers are required b/w spokes and hub flange. For this kind of build, are washers (on rim [Kinlin] and on flange) recommended or needed?
Washers on flange or not can affect durability, but they have no influence on initial trueness of a wheel. And washers on rims is not a generally approved part of wheel building, although it can let a builder "save" some situations.
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Old 07-22-10, 03:51 AM   #7
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531phile: I trued all the spokes to around 50kgf drive side and little less on non drive side.
That's about half way there. DS spokes should be 110+ depending on parts used.

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... I got scared after what I found and stopped it.
Odds are that at that tension your wheel is so floppy that the spokes aren't really pulling enough to be able to influence the rim to any significant degree. You really need to take the tension higher before you can say anything. Take up the slack first, then you can see how it goes.
Besides, you're not telling how big deviations you are seeing. If we're talking centimeters I might be concerned, but if it's down in the mms I'd happily go ahead.
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Old 07-22-10, 01:40 PM   #8
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This is not unusual at all.
As you increase tension work on radial true, making the wheel round. It is possible to have perfect tension and still be out of round. On 8, 9, and 10-speed rear wheels the non drive side spokes will need to have about 60 percent as much tension as the drive side to center the rim (dish).
Do the final tension and truing with the tire fully inflated. This makes a significant difference.
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Old 07-22-10, 03:17 PM   #9
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Set your tension meter aside and true up the wheel. Alternate between lateral and vertical trueing. When its true your done.
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Old 07-22-10, 04:33 PM   #10
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the tension on the left side will be as low as 50% of the right side with the Power-tap hub.
As you increase tension work on radial true, making the wheel round. It is possible to have perfect tension and still be out of round. On 8, 9, and 10-speed rear wheels the non drive side spokes will need to have about 60 percent as much tension as the drive side to center the rim (dish).
Be sure to stress relieve the wheel as the tension gets close.
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Old 07-22-10, 04:42 PM   #11
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Set your tension meter aside and true up the wheel. Alternate between lateral and vertical trueing. When its true your done.
Well, I'd say not quite done. It's probably better to alternate tension equalization and truing if you have a tension meter. Bringing up the tension slowly, maybe 10-20 kgf per iteration. At some point it will be a good balance between true and tensioned- but it won't be perfect for either.

Then tension relieve and true a couple of times more.
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Old 07-22-10, 06:46 PM   #12
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Well, I'd say not quite done. It's probably better to alternate tension equalization and truing if you have a tension meter. Bringing up the tension slowly, maybe 10-20 kgf per iteration. At some point it will be a good balance between true and tensioned- but it won't be perfect for either.

Then tension relieve and true a couple of times more.
As i said earlier....set the tension meter aside.......
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Old 07-23-10, 04:39 AM   #13
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Thanks for all the replies.

dabac: Yes, it is less than a cm.

davidad: Kinlin has 577ERD and the PT hub's center to sides are 32.4 and 17.4. Calculating for tension, it is 54%.

I'll continue over the weekend.

Last edited by praveendv; 07-23-10 at 04:39 AM. Reason: grammer!
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Old 07-26-10, 12:31 AM   #14
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Finally, the wheel is almost true. I have to sort out 1mm radial truing, on one quarter of the wheel. I plan to return to it in couple of days. I rode for close to half an hour and found no problems rechecking it.

The deflection on PT TM-1, from 14 to 15 for a 2.3 bladed spoke is 12. I can't get a granularity lesser than that. So, tension is set between 110 to 122 on the driveside.

miamijim: Thanks, btw, I had to set the TM aside for the final touch where I had to turn nipples for less than a 1/8 turn.

Al1943: Thanks for the tip. I found this article. I really did go from Figure 6 to Figure 8.

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