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Old 08-02-08, 06:05 PM   #1
TimJ
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Rim seam question

I'm building my first set of wheels, they're all laced up, gonna move onto tensioning and truing, etc... I noticed the seam on one of the rims isn't smooth. It's a 700c sun m14A and the ends don't meet flush. I can't remember if it was like this before I started building but the spokes aren't tight or anything yet so I don't see how it could have been pulled out of whack.

it's very slight. You can kind of see it but I didn't take any pics because I didn't think it would show up well enough, you can definitely feel it, one side is slightly higher and out to one side than the other. We're talking maybe 1/4 of a mm, perhaps 1/3 at worst.

Is this something I need to be concerned with? Would this be considered a defective rim or is it just unfortunate but still usable?
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Old 08-02-08, 06:10 PM   #2
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Did you get the left/right hole drillings in the rim matched up to the correct side of the hub?

The compression of the rim actually binds the seam together very tightly. So before I add tension with the spokes, I'll use a crescent wrench to align the rim-edges together at the seam. Then once it's tensioned, the rim-ends are forced together and held tightly.

The mis-alignment you have is way too much, even 0.1mm is enough to cause brake-shudder and pieces of the rim can flake off and get embedded in the brake-pad and scratch and wear out the rim prematurely. Personally, I'd undo the tension on the rim and re-align the seam to it better, then tighten it up again.
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Old 08-02-08, 06:52 PM   #3
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So before I add tension with the spokes, I'll use a crescent wrench to align the rim-edges together at the seam.
I Have never heard of this before, not from any pro wheelbuilder or sheldon brown even.
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Old 08-02-08, 06:54 PM   #4
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Hmmm. OK.

I think I have the drilling right but it's impossible to tell by eye. I was going off a book and if it was correct the label was supposed to be facing so that it was readable (right side up) from the cassette side, and it is.
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Old 08-02-08, 07:07 PM   #5
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Hmmm. OK.

I think I have the drilling right but it's impossible to tell by eye. I was going off a book and if it was correct the label was supposed to be facing so that it was readable (right side up) from the cassette side, and it is.
Which book? Not all rim-labels face the same direction. The key areas I look for are:

1. left/right spokes aimed at the correct flange so the spokes don't have an S-bend.
2. spokes on either side of valve-stem parallel for easy pumping
3. spokes on either side of seam pulling together to pinch the seam. Although in reality, it doesn't make a difference as the entire circumference of the rim is pulled inward and the seam is always pushed together.

These functional aspects I consider first and if I wanted an aesthetic thing like the label facing a certain way, I'll just peel it off and re-attach it the other way at the end.
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Old 08-02-08, 07:17 PM   #6
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It's not an aesthetic thing, from the book and sheldon's site it sounded like rims were drilled with a slight left/right orientation and the lable thing was just a trick used in order to get the orientation right.

They're laced correctly, everything is right unless I didn't get the rim facing the correct way. I don't know how I could possibly tell if it was facing the right or wrong way, I can't see any orientation to the drilling just by looking at them.
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Old 08-02-08, 07:35 PM   #7
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You know what? The rim is drilled wrong. the spoke holes are not equi-distant from the seam as on the rim I'm having no problem with. One hole is 2.5mm from the seam, the other 3.5, so they're not applying equal pressure at the seam- they can't. I bought this way back in january but I'm gonna see if I can get a replacement.
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Old 08-02-08, 11:51 PM   #8
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You mean there's a circumferential seam down the middle of the rim? Most likely you have an offset-drilled rim used to equalize the spoke-tension between left & right sides on the rear wheel. You'll want to have the spokes that's 3.5mm away from the middle going to the left non-driveside flange. The ones 2.5mm away should go to the right drive-side flange.
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Old 08-02-08, 11:56 PM   #9
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No, it's not a offset drilled rim. No, there's not a seam down the middle of the rim.

I'm saying the spoke holes on either side of the seam are not equidistant from the seam, since they're not equidistant they're pulling at it with different amounts and direction of force, causing the seam to shift. I'm pretty sure I would have noticed if the seam wasn't flush at the beginning, so it makes sense that the unequal pulling would cause the seam to go out of whack a little.
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Old 08-03-08, 12:14 AM   #10
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Hi, are u talking about the seam where the rim is joined all together? Not all the rims are perfect just in case. The wheel will get as true as the rim is. If the seam goes up a little bit in my opinion thats normal. In my whole life i have seen perfect rims probably twice. 1/4 of a mm is almost nothing dude.

Regarding the problems with the holes, wonder if you put a spoke in the valv hole, just a thought.

Always u can hammer the problem, im not kiding. a piece wood and a hammer will fix it. One side of the seam is lower than the other side. Sometimes u add like a little bit to the left in one side and then to the right. What you see is normal even in high end wheels.As i said u can fix it with a hammer if you like

Nothing it will happen anyways, after the wheel is mounted u wont even feel it. Stuff like that is not something you will notice even going at 120 kms/h going downhill.

Cya!

Good luck.
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Old 08-03-08, 12:58 AM   #11
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No, I didn't put a spoke through the valve hole...

I don't understand why no one gets this part- There is a seam. Every rim has a seam. There are spoke holes on either side of the seam. On this rim one spoke hole is 3.5cm away from the seam. The hole on the other side of the seam is 2.5cm away. They should be both 3cm away from the seam.

it should be (0=hole, |=seam):

0--------|--------0

not:

0----|------------0

If anyone has built a wheel where the spoke holes on either side of the seam weren't equidistant from the seam and everything was a-ok, I'd like to hear how you did it.
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Old 08-03-08, 09:07 PM   #12
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So what difference does it make? Either the seam lines up perfectly, (rare) or it doesn't (common). What does the distance to the spoke hole matter? Take it to the LBS and let them explain it to you.
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Old 08-03-08, 09:15 PM   #13
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Originally Posted by DannoXYZ View Post
You mean there's a circumferential seam down the middle of the rim? Most likely you have an offset-drilled rim used to equalize the spoke-tension between left & right sides on the rear wheel. You'll want to have the spokes that's 3.5mm away from the middle going to the left non-driveside flange. The ones 2.5mm away should go to the right drive-side flange.
So, Danno (or anyone), do all rims have left/right alignment to their holes?
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Old 08-03-08, 09:59 PM   #14
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Originally Posted by TimJ View Post

They should be both 3cm away from the seam.

it should be (0=hole, |=seam):

0--------|--------0

not:

0----|------------0

Why?
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Old 08-04-08, 09:57 AM   #15
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Why?

Because when I started to get the very least amount of tension the seam slid apart, presumably because the forces were unequal. I've looked at every wheel I have and they all have the seam at an equal distance between two spoke holes.

Now, are you guys telling me you know for a fact it doesn't matter where the seam is, as in you have wheels with the seam closer to one spoke hole than the other, or you've built wheels like this, or is that your guess?
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Old 08-04-08, 10:04 AM   #16
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So, Danno (or anyone), do all rims have left/right alignment to their holes?

From Sheldon's site and the book I was using, that's the impression I get:

Quote:
This spoke must be in the right place or the valve hole will be in the wrong place, and the drilling of the rim may not match the angles of the spokes.

...

Rims are drilled either "right handed" or "left handed". This has to do with the relationship between the valve hole and the spoke holes. The spoke holes do not run down the middle of the rim, but are offset alternately from side to side. The holes on the left side of the rim are for spokes that run to the left flange of the hub. with some rims the spoke hole just forward of the valve hole is offset to the left, with others it is offset to the right (as illustrated). Which type is "right handed" and which "left handed"? I have never met anyone who was willing to even make a guess!

But for the life of me I couldn't tell by looking at the holes which way they were oriented. I just went off what the book I had said, which made is sound like the majority of rims are drilled the same way- in terms of being left or right handed- so while the front wheel I made is properly laced and I've got it trued and tensioned and it turned out real nice... I'm still not sure if I got the right/left orientation correct.
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Old 08-04-08, 10:35 AM   #17
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So I called sun ringle and the guy first told me that on their rims, if you've got the rim facing you (label readable) the spoke hole that is 2 over from the valve hole will be a drive-side spoke. That's how you get the right orientation.

Then on the seam he said he didn't know what the tolerances were in regards to where it should be, but he's never seen a rim where the seam wasn't an equal distance from the spoke holes and 1cm difference sounds like a lot, so I'm gonna send it in for replacement. I guess I'll find out once they get it if directly in the middle is the proper way to build it.
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Old 08-04-08, 12:06 PM   #18
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So, Danno (or anyone), do all rims have left/right alignment to their holes?
My DT Swiss RR 1.1 rims are drilled on-center, no offset. The rim seam is equidistant from the nearest spokes. On my Open Pro rims the seams are so tight I had a hard time finding them, the nearest spokes are also equidistant from the seam. The better rims are welded at the seam so this may not be an issue.
I think you are doing the right thing by sending them back to the manufacturer.

Al

Last edited by Al1943; 08-04-08 at 12:15 PM.
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