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True wheel has slack spoke, doesn't stay true



 
 
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  #1  
Old December 6th 05, 03:31 PM posted to rec.bicycles.tech
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Default True wheel has slack spoke, doesn't stay true

My first handbuilt set of wheels I built with the help of the LBS.
Without knowing what to choose, I went with DT Revolution spokes and
aluminum nipples to lace my Chorus hubs to Open Pro rims. The front
wheel has been fine and has only needed truing once to fix a few spokes
that had been left with some wind up in them. Since then it has stayed
true.

The rear wheel, however, has been a real pain. I have one spoke that is
one spoke away from the weld on the non-drive side that only has a few
kg of force on it. No matter what I do, if the other spokes are
tensioned properly and the wheel is round and true, this one spoke will
only have a little force on it. I can't see that the rim has anything
more than the usual amount of out of round near the seam and there is
no damage. It's been like this since new. This wheel never stays
perfectly true even through one ride, and I suspect that this plus the
aluminum nipples has something to do with this.

Should I just accept a bit out of roundness on that part of the wheel
to get some tension there, or are there any other suggestions?

Thanks,
Tad

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  #2  
Old December 6th 05, 03:38 PM posted to rec.bicycles.tech
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Default True wheel has slack spoke, doesn't stay true

On Tue, 06 Dec 2005 07:31:54 -0800, Tad Marko wrote:

The rear wheel, however, has been a real pain. I have one spoke that is
one spoke away from the weld on the non-drive side that only has a few
kg of force on it. No matter what I do, if the other spokes are
tensioned properly and the wheel is round and true, this one spoke will
only have a little force on it.


The rim has a flat spot. Not really uncommon at the seam. You can try to
push it out some; people have suggested removing the spokes in that area
and pressing the rim out with a car jack. I haven't actually tried that,
though. You might also construct a jig with the proper curvature to
re-shape the rim. Or get another rim.


true even through one ride, and I suspect that this plus the aluminum
nipples has something to do with this.


Well, aluminum nipples and Revolution spokes do make the wheel harder to
tension properly.

Should I just accept a bit out of roundness on that part of the wheel to
get some tension there, or are there any other suggestions?


Barring surgery on the rim itself, I'd seriously look at replacing the
right side spokes with something more substantial, and use brass nipples
there. Then you can get adequate tension on the wheel.

--

David L. Johnson

__o | I believe that the motion picture is destined to revolutionize
_`\(,_ | our educational system and that in a few years it will supplant
(_)/ (_) | largely, if not entirely, the use of textbooks -- Thomas
Edison, 1922

  #3  
Old December 6th 05, 03:57 PM posted to rec.bicycles.tech
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Default True wheel has slack spoke, doesn't stay true

I agree that the rim must have a flat spot. The symptoms described are
exactly those of a flat spot.

  #4  
Old December 6th 05, 06:20 PM posted to rec.bicycles.tech
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Default True wheel has slack spoke, doesn't stay true

Tad Marko wrote:
My first handbuilt set of wheels I built with the help of the LBS.
Without knowing what to choose, I went with DT Revolution spokes and
aluminum nipples to lace my Chorus hubs to Open Pro rims. The front
wheel has been fine and has only needed truing once to fix a few spokes
that had been left with some wind up in them. Since then it has stayed
true.

The rear wheel, however, has been a real pain. I have one spoke that is
one spoke away from the weld on the non-drive side that only has a few
kg of force on it. No matter what I do, if the other spokes are
tensioned properly and the wheel is round and true, this one spoke will
only have a little force on it. I can't see that the rim has anything
more than the usual amount of out of round near the seam and there is
no damage. It's been like this since new. This wheel never stays
perfectly true even through one ride, and I suspect that this plus the
aluminum nipples has something to do with this.

Should I just accept a bit out of roundness on that part of the wheel
to get some tension there, or are there any other suggestions?


It sounds like the rim has a flat spot, so when true, that one spoke is
too loose to not unscrew when the wheel gets loaded in riding. If
getting the rim true (or replacing it) is too much of a bother, I'd just
try assembling that one spoke with some Locktite. Is the opposing (right
side) spoke also at a lower tension than its neighbors? It could be that
this is just a case of uneven tension rather than a bad rim (seeing how
it's your first wheel).
  #5  
Old December 6th 05, 06:51 PM posted to rec.bicycles.tech
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Default True wheel has slack spoke, doesn't stay true

On 6 Dec 2005 07:31:54 -0800, "Tad Marko" wrote:


Should I just accept a bit out of roundness on that part of the wheel
to get some tension there, or are there any other suggestions?


Flat spot. Not uncommon. Sometimes, just running up the tension on
the rest of the spokes and re-truing the wheel will get enough tension
on the flat-spotter to keep it from being a problem. Brass nipples
would probably be a good idea if you're going o try this. How much
tension is on the rest of the spokes, and how did you measure it?
--
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  #6  
Old December 6th 05, 07:04 PM posted to rec.bicycles.tech
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Default True wheel has slack spoke, doesn't stay true

Around 100 kgf according to the Park tensionometer.

  #7  
Old December 6th 05, 07:07 PM posted to rec.bicycles.tech
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Default True wheel has slack spoke, doesn't stay true

The thought has occured to me to replace all the rear spokes with DT
Champions and brass nipples. The front wheel is currently falling into
the category of it ain't broke so it don't need fixin'.

  #8  
Old December 7th 05, 12:47 AM posted to rec.bicycles.tech
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Default True wheel has slack spoke, doesn't stay true

Tad Marko wrote:
The thought has occured to me to replace all the rear spokes with DT
Champions and brass nipples. The front wheel is currently falling into
the category of it ain't broke so it don't need fixin'.


Using thicker spokes would not solve the problem - in fact it might
make things worse; you would almost certainly have problems with
breakage of the slack spoke. Have you tried loosening the two spokes
on the either side of the loose one (on the same side of the wheel as
the loose one) about a quarter turn,say, and then bringing the wheel
back to left-to-right trueness by tightening the problem spoke?

Best wishes,

Nigel Grinter
Well-Spoken Wheels Inc.
(wellspokenwheels.com)

  #9  
Old December 7th 05, 01:10 AM posted to rec.bicycles.tech
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Default True wheel has slack spoke, doesn't stay true

If you can't feel it when riding then just forget about it. I must have
rebuilt my rear wheel(s) about five times. They both have a little
out-of-round blip of about 1.5mm. But when out riding I don't notice a
thing so the heck with it. My final solution is to eventually replace
these rims and start all over again.

  #10  
Old December 7th 05, 03:13 AM posted to rec.bicycles.tech
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Default True wheel has slack spoke, doesn't stay true


David L. Johnson wrote:

The rim has a flat spot. Not really uncommon at the seam. You can try to
push it out some; people have suggested removing the spokes in that area
and pressing the rim out with a car jack. I haven't actually tried that,
though. You might also construct a jig with the proper curvature to
re-shape the rim.


I've removed flat spots from my rims several times. It didn't take a
car jack. I used a bench vise and blocks of wood.

I took a piece of 1" x 4" board, perhaps 10" long, and fastened a block
cut from 2" x 4" on each end. The blocks have an angled surface, to
match the rim's angle. This supports a span of the rim from the
outside. Another block of wood presses against the flat spot on the
inside (i.e. hub side), with several spokes removed for clearance.

The sandwich fits into my bench vise. I tighten bit by bit, loosening
occasionally to check if I've moved the rim enough. It's a bit fussy,
but not too bad. Way easier than buying new components and building a
new wheel, and much cheaper.

- Frank Krygowski

 




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