Wheel Building Woes

[confusedcyclist]

I'm having a bit of trouble with my latest wheel build.

I am pretty sure I have done my spoke calculations correctly, I even used two separate online calculators and remeasured the hub flanges and ERD to ensure this. So, unless the bike shop shop gave me the wrong spokes lengths, something else is up.

When assembling, the nipple for every 3rd and 4th spoke (from opposing sides of the rim) won't clear the rim's eyelets, even when all the nipples are tensioned on the first pass using a nipple driver. It's odd, because the 1st and 2nd spokes (also opposing sides) are a perfect fit. I'm making the 3 cross pattern, and I rotated the hub fully and held it in place before lacing the 3rd set of spokes. I have built 3 cross every time before, this is my 7th build, but for the life of me can't work out what's going wrong.

I'm trying to think logically what would make every 3rd and 4th's spoke be too long for this 3x pattern, but am coming up with nothing.

 

[Yellow Saddle]

Are you sure you are skipping the right number of spaces when crossing the 3rd spoke?


Let me double-check your spoke calculations for you.

What is the ERD?
What is the OLD of the two hubs?
What is the spoke hole diameter?
What is the spoke circle diameter?
What spokes are you using?
What is the hub flange offsets on the two hubs?
What number of crossings are you planning (I assume 3X)

 

[confusedcyclist]

Are you sure you are skipping the right number of spaces when crossing the 3rd spoke?

I'll double check when I return from work, I think this might be the most rational explanation, if the spoke calcs are right, it would make sense that the spokes are not travelling far enough to the intended eyelet...

What is the ERD? 602mm
What is the OLD of the two hubs? 130mm
What is the spoke hole diameter? 2.6mm
What is the spoke circle diameter? 45mm (both sides)
What spokes are you using? Sapim Race (double butted) 289mm spokes on drive side and 291mm non-drive side, those were the closest I could get at the time.
What is the hub flange offsets on the two hubs? 36mm/17mm
What number of crossings are you planning (I assume 3X) Yes, 3X, both sides

Rim - Mavic Open Pro Clincher (manufactured 2016 - 36 spokes)
Hub - Shimano FH-5800

 

[Yellow Saddle]

I'll double check when I return from work, I think this might be the most rational explanation, if the spoke calcs are right, it would make sense that the spokes are not travelling far enough to the intended eyelet...

What is the ERD? 602mm
What is the OLD of the two hubs? 130mm
What is the spoke hole diameter? 2.6mm
What is the spoke circle diameter? 45mm (both sides)
What spokes are you using? Sapim Race (double butted) 289mm spokes on drive side and 291mm non-drive side, those were the closest I could get at the time.
What is the hub flange offsets on the two hubs? 36mm/17mm
What number of crossings are you planning (I assume 3X) Yes, 3X, both sides

Rim - Mavic Open Pro Clincher (manufactured 2016 - 36 spokes)
Hub - Shimano FH-5800

The EDR of an OpenPro rim is actually 604. But that' doesn't make a big enough difference unless you have rounded down severely, which you have not.

Basically, your spokes are OK.

The mathematical length is 292.4 and 290.7, but since you can safely round down by at least 2mm with those spokes, your 291 and 289 is perfect.

Therefore, I suspect your (as much as I hate the bloody word) "geometry" with which you're trying to build. To put it bluntly, the angles are all wrong because you skipped the wrong number of holes. Remember, when you are on your 3rd spoke, it goes into the next available spoke hole as seen from away from the valve hole. In other words, it becomes the 3rd consecutive spoke on the batch of 3, not the 1st spoke in the next batch.

If that is what you are trying to do, things went wrong with the second set. Just double-check that your second set of spokes went into the first available spoke hole away from the valve hole.

 

[normgow]

It is important to ascertain whether you have a type A or type B rim. Look down onto the rim with the valve hole at the top. On type A the first spoke hole forward of the valve hole will be offset to the right. On type B it will be the second hole. Most rims are type B. Your first spoke on the freewheel side should go into this right side offset hole forward of the valve hole.

 

[confusedcyclist]

It's type B, I know for sure because I have successfully built a wheel with this exact rim before. I'm just swapping the hub. I didn't get a chance to look at this build this weekend because I was busy fitting the new 5800 groupset to my road bike. I'll update the thread soon with images if I can't work out what went wrong.

 

[Ian H]

An old-fashioned way of describing spoke crossing is by 'span'. 3X is 7-span; that is, two adjacent, crossing spokes should be7 holes apart inclusive (that is, 5 clear holes between them).

 

[Nigelnightmare]

Pictures of the wheel in question would be helpful

 

[XC26]

Check all the spokes are the same length - just standing them upright in a bunch on a hard, flat surface should do. To achieve the degree of anomaly that you have encountered would require spokes that are way different in length.

It seems like you have just laced it up incorrectly. I have done this a few times, having built many wheels perfectly before. I can remember one occasion when I couldn't for the life of me understand what was wrong and took ages to spot that I had managed to lace it with some adjacent spokes at the rim going to the same side of the hub.

Logically, if all the spokes are the same length but too long for the hub/rim combination, you would end up with a very wobbly wheel with all the spokes similarly loose. If the spokes are of a marked difference in length or if the lacing is incorrect, I would expect results like you have encountered.

 

[confusedcyclist]

Bit late in the day, but only just got a chance to look at this again... busy decorating new home! Spokes were fine, I just laced it up wrong. Doh!

Thanks all for the help.

 

[confusedcyclist]