Confused about which way I need to round my spoke length.

dcgriz · Feb 27, 2017

Lombard said:
Now here's the trick question. If calculations come out to say 289.0 and the choices are only evens....288 and 290. Which way would you go? Roger Musson is OK with either choice and I doubt it really matters. Does anybody here have a definite choice?

The first thing I do is check my measurements and predominantly re-verify/remeasure the rim ERD to make sure that the average I took is correct. If this checks out then I round-up for the following two reasons:
a) I dont like to have the spokes start tightening too early when building and
b) In the event that I screwed up my measurements (even after I re-verified; has not happened yet) I could adjust for shorter needed spokes by changing my standard Sapim nipples to DT and salvage the spokes. Murphy's law response basically. Have not had to put this to use yet but it makes sense to me since nipples are much cheaper than spokes

Lombard · Feb 27, 2017

dcgriz said:
The first thing I do is check my measurements and predominantly re-verify/remeasure the rim ERD to make sure that the average I took is correct. If this checks out then I round-up for the following two reasons:
a) I dont like to have the spokes start tightening too early when building and
b) In the event that I screwed up my measurements (even after I re-verified; has not happened yet) I could adjust for shorter needed spokes by changing my standard Sapim nipples to DT and salvage the spokes. Murphy's law response basically. Have not had to put this to use yet but it makes sense to me since nipples are much cheaper than spokes

Hmmm. Well since I use DT spokes and nipples, I guess that means I should in theory round-down? That way if they are too short, I could change to Sapim nipples?

dcgriz · Feb 27, 2017

Lombard said:
Hmmm. Well since I use DT spokes and nipples, I guess that means I should in theory round-down? That way if they are too short, I could change to Sapim nipples?

That would be a logical deduction if you used Sapim nipples to measure the rim ERD and the Wheelpro calculator to size the spokes.

MudSnow · Feb 27, 2017

There are 10-12mm of thread in the nipples, so if the spokes are 1mm short, it won't matter. But you can get 14mm nipples. So I round down.

Lombard · Feb 28, 2017

MudSnow said:
There are 10-12mm of thread in the nipples, so if the spokes are 1mm short, it won't matter. But you can get 14mm nipples. So I round down.

Hmmm. Now there's a simple inexpensive solution!

November Dave · Feb 28, 2017

Mike T. said:
Edit. Ok this bit just clicked in - "we'll be selling spokes". You gonna be selling all wheel parts?

Not all, but some. Not trying to get into an already crowded market of selling commodity stuff, but where we can provide unique access to a product, or add value to the selling of a product, or something along those lines, we will.

On the other topic, I may be exposing some stupidity here, but I've never gotten the deal with varying nipple lengths. I want the spoke end to wind up in the same precise position relative to the rim every time - call it +/- 2.5mm inside the spoke bed of the rim. To me, longer nipples are useful when you have a rim with a thick spoke bed, like carbons, or rims with very sharp v points, where a 12mm doesn't give enough access to the wrench flats.

I'm aware of the nipples that have a longer "back end" like the Squorx (?) nipples from DT, and Sapim has an equivalent. I think American Classic actually invented the concept. And those give more tolerance to making spokes slightly too long. But on a regular nipple, to me a spoke that's too short with a 12mm nipple is still going to be too short with a 14mm nipple. What am I missing there?

Lombard · Feb 28, 2017

November Dave said:
Not all, but some. Not trying to get into an already crowded market of selling commodity stuff, but where we can provide unique access to a product, or add value to the selling of a product, or something along those lines, we will.

On the other topic, I may be exposing some stupidity here, but I've never gotten the deal with varying nipple lengths. I want the spoke end to wind up in the same precise position relative to the rim every time - call it +/- 2.5mm inside the spoke bed of the rim. To me, longer nipples are useful when you have a rim with a thick spoke bed, like carbons, or rims with very sharp v points, where a 12mm doesn't give enough access to the wrench flats.

I'm aware of the nipples that have a longer "back end" like the Squorx (?) nipples from DT, and Sapim has an equivalent. I think American Classic actually invented the concept. And those give more tolerance to making spokes slightly too long. But on a regular nipple, to me a spoke that's too short with a 12mm nipple is still going to be too short with a 14mm nipple. What am I missing there?

Good explanation Dave! Brain fart on my part. Yes, if a spoke thread won't make it to the head of the 12mm nipple, it won't make it to the head of the 14mm nipple - DUH! :idea:

Mike T. · Feb 28, 2017

November Dave said:
On the other topic, I may be exposing some stupidity here, but I've never gotten the deal with varying nipple lengths. I want the spoke end to wind up in the same precise position relative to the rim every time - call it +/- 2.5mm inside the spoke bed of the rim. To me, longer nipples are useful when you have a rim with a thick spoke bed, like carbons, or rims with very sharp v points, where a 12mm doesn't give enough access to the wrench flat.................to me a spoke that's too short with a 12mm nipple is still going to be too short with a 14mm nipple. What am I missing there?

I don't think you're missing anything. I don't have enough experience, especially fudging up incorrect spoke lengths with longer nipples, to contribute to earlier comments on this. To me it's dead simple - the spoke ends up at the bottom of the slot or it's a cock-up. Something went "wrong" - my measuring or the calculator's behind the scenes workings (I measure all spokes when I get 'em - some have been wrong). Oh sure even me with some OCD can live with spokes within the "+/-1mm" - leaving spokes at the top of the slot or 1/2 way down the nipple head. But I wouldn't juggle nipples to fudge up a deviation from this. I'd re-order the right length, and have in the past.

Yes I agree - longer nipples are for thicker nipple beds. End of.

Lombard · Feb 28, 2017

Mike T. said:
.....(I measure all spokes when I get 'em - some have been wrong).....

Eeeegad! All I did was gather them and make sure they were all the same length. So you're more OCD than I for sure!

But in both my builds, when the wheel was finished, the spoke came up at least to the top of the nipple head and never "bottomed out". Or should I say "topped out"?

Mike T. · Feb 28, 2017

Lombard said:
Eeeegad! All I did was gather them and make sure they were all the same length. So you're more OCD than I for sure!

I've been caught 2x with incorrect spoke lengths in the last two years. One time, it was like a handful of spokes had been thrown back in the wrong bin. I had 12 of one length and 14 of another. So now I take 5 mins with the spoke ruler and measure each one. That saves me wasting hours.

You'd think I'd build a gizzmo to hang all of them from wouldn't ya? Then that way I just have to measure one.

Lombard · Feb 28, 2017

Mike T. said:
I've been caught 2x with incorrect spoke lengths in the last two years. One time, it was like a handful of spokes had been thrown back in the wrong bin. I had 12 of one length and 14 of another. So now I take 5 mins with the spoke ruler and measure each one. That saves me wasting hours.

You'd think I'd build a gizzmo to hang all of them from wouldn't ya? Then that way I just have to measure one.

OK, I see why for you it's an issue because you build so many wheels. I take the right sizes right out of the boxes to use. Both my builds used 288 rear DS and 290 rear NDS and front. Hard to mix up.

Mike T. · Feb 28, 2017

Lombard said:
OK, I see why for you it's an issue because you build so many wheels.

No I don't and I've never said that I do. Lots of people assume that because of my site. I said recently that November Dave will build more wheels in a morning than I do in a year - about 2 sets for myself, and only that many as I like to try & test a few rims. I don't ever want to build wheels for other people. My schick is motivating people to start building their own. Heck I don't give 'em all the info either so they have to be curious and search elsewhere (aka Roger's e-book).

I take the right sizes right out of the boxes to use. Both my builds used 288 rear DS and 290 rear NDS and front. Hard to mix up.

So you assume all the spokes in the box are the right size eh? You have more faith than I do.

zucchiniboy · Feb 28, 2017

If you were in a "round up" vs "round down" conundrum, couldn't you add nipple washers to adjust so it's closer to what the ideal length is? i.e., say a measurement called for 289mm, but you only had access to even lengths, you could add nipple washers (effectively increasing the ERD) to those spokes and go with 290mm, right?

Mike T. · Feb 28, 2017

zucchiniboy said:
If you were in a "round up" vs "round down" conundrum, couldn't you add nipple washers to adjust so it's closer to what the ideal length is? i.e., say a measurement called for 289mm, but you only had access to even lengths, you could add nipple washers (effectively increasing the ERD) to those spokes and go with 290mm, right?

I've done that before as they add 1.4mm to the ERD. But it becomes a moot exercise as I normally use nipple washer and I use then on my dummy spokes for measuring ERD so they're already factored in. I guess I could use a 2nd set of washers eh?

dcgriz · Mar 1, 2017

November Dave said:
I'm aware of the nipples that have a longer "back end" like the Squorx (?) nipples from DT, and Sapim has an equivalent. I think American Classic actually invented the concept. And those give more tolerance to making spokes slightly too long. But on a regular nipple, to me a spoke that's too short with a 12mm nipple is still going to be too short with a 14mm nipple. What am I missing there?

Dave,

That's not necessarily true.

Let's put it this way, a spoke that is 1mm too short with a Sapim 12mm nipple will also be 1mm too short with either a 14mm or 16mm Sapim nipple.
To the contrary, a spoke that is 1mm too short with a Sapim 12mm nipple will be just right with a DT 14mm nipple and 1mm too long with a DT 16mm nipple.

The reason for this is the nipple thread length. Sapim maintains constant thread length in all of their nipples so the spoke length good for the 12mm is also good with the 14 and the 16mm.
DT varies the thread length incrementally by 1mm from the 12mm to the 16mm per 2mm of added nipple length. So the spokes for the 14mm and the 16mm are 1mm and 2mm shorter than the spokes for the 12mm. This is based on the ERD measurements being done with 12mm nipples.

Roger Musson's ebook shows a cut-out view of the DT nipple thread length for each nipple size and very nicely further explains all this.

Needless to say, this is not a reason to use anything but 12mm nipples, unless the rim bed needs it of course. It is just another piece of info that may salvage a bunch of spokes if Mr. Murphy knocks on the door.

Lombard · Mar 1, 2017

Mike T. said:
No I don't and I've never said that I do. Lots of people assume that because of my site. I said recently that November Dave will build more wheels in a morning than I do in a year - about 2 sets for myself, and only that many as I like to try & test a few rims. I don't ever want to build wheels for other people. My schick is motivating people to start building their own. Heck I don't give 'em all the info either so they have to be curious and search elsewhere (aka Roger's e-book).

Understood. My point was that you have built way more wheels than I have. From your previous post, it sounds like you have an inventory of quite a few different sizes of spokes. So being meticulous and categorizing them is important to avoid mix ups.

Mike T. said:
So you assume all the spokes in the box are the right size eh? You have more faith than I do.

As I said before, I took all the spokes out of the box and gathered them together to verify for myself that they were all the same length. Maybe I should have measured them to be thorough. I "got away" (yes, I know you hate that term

) with not measuring the spokes and trusted my shop and the manufacturer that they labeled the boxes correctly. But you are correct of course, to be better safe than sorry in order to save a potential waste of time and avoid lots of cursing. Next time!

Lombard · Mar 1, 2017

dcgriz said:
The reason for this is the nipple thread length. Sapim maintains constant thread length in all of their nipples so the spoke length good for the 12mm is also good with the 14 and the 16mm.
DT varies the thread length incrementally by 1mm from the 12mm to the 16mm per 2mm of added nipple length. So the spokes for the 14mm and the 16mm are 1mm and 2mm shorter than the spokes for the 12mm. This is based on the ERD measurements being done with 12mm nipples.

This is certainly an interesting observation. Me thinks that if the thread length increases with nipple length and spoke threads don't also increase, a longer nipple will result in less of the spoke thread getting into the nipple head, resulting in a weaker connection between spoke and nipple.

dcgriz · Mar 1, 2017

Lombard said:
This is certainly an interesting observation. Me thinks that if the thread length increases with nipple length and spoke threads don't also increase, a longer nipple will result in less of the spoke thread getting into the nipple head, resulting in a weaker connection between spoke and nipple.

This is the ramification of using the DT 16mm. Their 14mm is not as bad because it ends up with what could be argued as adequate support for the nipple shoulders. The 12mm obviously offers the most support. Its also interesting to note that the DT spoke calculator automatically adjusts the spoke length to account for 14mm and 16mm nipples.

Anyway, I think this whole DT nipple thread length thing is more confusing than arguably helpful but, as I said before, there may be a case where it could be useful to know. If nothing else file it away in your data bank. That's all.

Mike T. · Mar 1, 2017

Lombard said:
From your previous post, it sounds like you have an inventory of quite a few different sizes of spokes.

Not at all. I have a couple of other sets that were sent to me incorrectly and it's too expensive to ship them back so they just send out a new batch. So I had a couple of sets laying around.

being meticulous and categorizing them is important to avoid mix ups

Tell that to the people at the other end. It was their people who must have thrown some spokes in the wrong bin. But that's just an assumption on my part. They could have arrived at the distributor from the maker already mixed up. But the bottom line is the same - trust no-one but yourself using your own eyes.

sheepherder · Nov 18, 2017

MudSnow said:
Yes, I build with mostly CX-Rays and they definitely stretch. I guess I generally round up not more than 0.5mm and round down as much as 1.5mm.

Mike T. said:
Yes with CX-Rays and Laser I stretch (is that a pun?) the rule a bit but most newbs don't build with those spokes from the get-go (at least they don't if they follow my site's warnings).

Edit. Ok this bit just clicked in - "we'll be selling spokes". You gonna be selling all wheel parts?

November Dave said:
This is what I'd say, yes. We use a Phil Wood spoke machine (best money ever spent) so size to .5mm resolution, but that's possibly a distinction without a difference. If you can only get odd or even lengths, Mike's advice is good. I'd include CX Rays with the default "round down" group.

As soon as we get the page built we'll be selling spokes in 1mm increments to give people access to more precise lengths.

I'm building with cx rays, 24/28 with dura ace hubs, hed c2 rims (erd592) 2 cross front and back

The problem I'm having is most sites calculate my front spoke length at 287.7 and rear at 281.7 and right around 284.

However when I use the wheelpro site it brings these number down significantly, front would be 286.6 which means I would go down to 286. Why is there such a big difference between the measurements?

It also changes what length I would need in the rear. What site should I follow? Or can I just round everything down with cxrays? If the other sites are correct though I would be rounding down 1.7mm for the front

Confused about which way I need to round my spoke length.

dcgriz

Lombard

dcgriz

MudSnow

Lombard

November Dave

Lombard

Mike T.

Lombard

Mike T.

Lombard

Mike T.

zucchiniboy

Mike T.

dcgriz

Lombard

Lombard

dcgriz

Mike T.

sheepherder

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