BikingGrad80

Hi all I am trying to rebuild a rear Open Pro Ultegra with a new rim and and having issues.

Brand new rim. I laced it up and it looks reasonable with no tension ie not very untrue looking on the truing stand laterally and radially when spun but when I get ready to start I notice two spokes near the valve hole seem longer to the point the nipple is barely visible with two threads showing. I don't think they really are though. So as I start adding tension there is no tension building on those two spokes so once I start getting tension I get out my tensiometer and bring them up to equal tension. However that spot becomes so out of true laterally that no ammount of truing will correct it. Could the rim be defective. The only issue I've had with OP's in the past were minor flat spots at the point but I remember it was a more difficult build than the CR18's I've done in the past. Suggestions?

cale

It's one of three things...

It's pretty easy to sort out if it's the rim. Take a measurement of the rim's effective rim diameter using a pair of spokes at various places around the rim. Maybe it's defective.

You don't mention the nipples but is it possible you forgot washers? Used a different length nipple? A different length spoke? Made a lacing mistake?

Retro Grouch 

Is it just 2 spokes or is the pattern repeated around the wheel?
I'd check your spoking pattern.

BikingGrad80

This time I started with the two spokes in question screwed in much further. I am pretty sure they are just longer than the others given the nipple protrusion. This build is a real bear. I've been truing for hours.

Jeff Wills

If so, stop. Before you get any more tension on the wheel, just stop. Mark the suspect spokes somehow, then disassemble the wheel completely. Remember that your right-side spokes should be a couple millimeters shorter than the left side, so keep the sides separated. Make sure that your suspect spokes are the same length as the rest. If they aren't, there's your problem.

If the spokes are the correct length and the same length throughout each set, the problem is with your technique- you messed up somewhere. You missed a crossing, got two spokes from opposite sides of the flange pointing the same direction, some other fumducker. Don't beat yourself up about it- I've been building wheels for 35 years and I still pull an occasional fumducker. Fix it, finish the wheel, and go ride.

ClarkinHawaii

Well, if you remove the 2 offending spokes and measure them, you will have your answer.

Huh, Jeff beat me to it.

BikingGrad80

Yea 2 must be the wrong length or something but still every time I add tension it ends up the same problem. I get to the point where there is that area where I cannot get the rim centered even with max tension on one and min on the other.

ClarkinHawaii

If the spokes are too long you are bottoming out the thread/nipple connection before the spoke gets tight enough to true the wheel.

BikingGrad80

I am measuring the tension each time with the park tensiometer. Also this was a store wheelset many years ago I am pretty sure the spokes are all the same size also why would 2 different sized spokes end up right next to each other. I trashed the old rim last week and just taped the rims and transfered the spokes. This is very peculiar. I have tried detensioning and retensioning 3 times in each case I reach an impass at the same spot. Also it is just impossible to true. Everytime I make progress on one area another goes bad until I get to the impass at that one spot where it is impossible to true.

BikingGrad80

Well I am just going to try replacing those two spokes as at this point there is nothing else I can do. I've built 5 wheels before and never had anything like this. It seems though as though something about the spoke/hub is intrinsically pulling the rim out of true at that spot as the tension goes up.

Retro Grouch 

If that's the case, I'd suggest disassembling the entire wheel and start over by comparing spoke lengths. You'll never get a good wheel if you are starting with inconsistent parts. If two are the wrong length, what makes you think the rest of the spokes are uniform?

SquidPuppet

Ten bucks says you have a cross wrong somewhere.

Starting from scratch would be less frustration than what you are experiencing now.

BikingGrad80

Nope I never laced these. They were originally store bought open pro/ultegras, I rerimmed them once a while back, and am doing so again (don't mess with the lacing just tape the two rims together and transfer). I must have used two wrong sized spokes from my other wheel in a pinch and I can't remember. I'll just buy proper length. I laid the rim on a table and it seems pretty planar with no tension.

BikingGrad80

Well I just went to purchase 2 new spokes based on calculated values. The new spoke is identical in length to the problem spoke I just took out there is no issue with the old spoke. The only thing I can think is that the rim has a defect and is egg shaped. I didn't think I ever replaced any of the spokes on that rim so that means all the spokes are the correct length after-all they just came off a good build. I checked the lacing patern and it is correct. over over under for 3X. I guess I'll have to contact Mavic or the CRcycles where I got it from. As I stated in the original thread Once I get set up for the build the two spokes (near the valve hole) the nipple is barely visible past the socket at the starting point (2 threads showing).

In the meantime I ordered a set of Forte Titans from Performance while I sort this mess out.

BikingGrad80

I tried building it one last time. The same thing happened again. I start with two threads showing and when I start working on radial true I have to add 3 full turns to the two spokes and it goes off lateral true badly to the nondrive side and cannot be corrected and the drive side spoke starts to bottom out with the thread.

zacster

My first thought, and I'm surprised it hasn't been suggested already, is that the rim is depressed at the spoke holes, making it seem like the spokes are too long. And I don't understand why you didn't just take a spoke from the same side and compare right from the start.

BikingGrad80

You mean has a flat spot at that section? Well I contacted customer support. I didn't want to start disassembling the wheel. I am surprised though a high quality rim like the OP defective/bent from the start though I have had issues with slight flat spots on previous OP rims at the joint I just build and rode them regardless. Easiest builds I've had were Cxp-11's and Sun-Cr18's I am leaning towards just returning the rim and riding with the Forte Titans for now and building a whole new wheel with both front and back hubs over the winter with one of the suggestions on the other threads like the Kinlin's.