ClarkinHawaii

My first shot at wheel-building from scratch.

I ordered the spokes cut to order in the 3 lengths obtained from spocalc.

When the spokes arrived, i randomly measured a few with my Park Spoke Ruler and discovered that they are all (all three different sizes) between 1-1.5 mm longer than specified.

The uniformity of the errors suggests that their spoke-cutting machine is out of adjustment, so I sent them an immediate email so they could check it before doing more orders.

I also gave them the choice of my exchanging the spokes for ones of the specified lengths now, or proceeding with the wheelbuild with the option of exchanging them later if a problem develops. Of course they will be greasy and bent at that point.

If they say go ahead and use them, I'm wondering about the possibility of problems down the line. From my limited knowledge, I would think that if I can adequately tension and true the wheels now without spoke-length-related problems, then the wheels are good to go for the long haul.

Am i correct in this? Thanks.

mrrabbit 

It's not the spoke machine that's out of adjustment - it's the human operating it.

If the ones for the rear are 1-1.5mm too long, then some are probably fine for the front.

Either send all back...or find a way to minimize the sendback. If you are using double wall rims and you aimed for the nipple screwdriver flat in your measurement - then use liberal nipples (such as DT 10mm nipples) that allow a good 2-3 threads past the top.

I'm sure others will pop-in with more options...

=8-)

fietsbob

If the nipples bottom out on the end of the thread, before reaching adequate tension, then the wheel durability will be reduced , or it will just be a waste of time and money , who's Data was used to determine the proper spoke length ?..

If the spokes do reach adequate tension , before hitting thread bottom, and there is spoke above the head of the nipple inside the rim, many a mass produced wheel will hit the excess spoke length with a Dremel grinder and take the proud end of the spoke off.

I would only bent the last 1/4 of the spokes when I build wheels .
I use Anti-Seize on the spoke threads of my wheel builds.

ClarkinHawaii

I used the hub and rim specs from Rinard's latest database. I verified the hub measurements with my calipers but I don't have "rim-sticks" or whatever they're called so I just trusted the database for the Mavic A119 rim.

ClarkinHawaii

I don't know what I "aimed for". I just plugged in the data and Spocalc spoke to me. What is Spocalc aiming for is the real question.

desconhecido 

Spokecalc will give you the computed value based on the numbers you insert -- it's not aiming for anything. The "effective rim diameter" that you insert into the program is the diameter of the circle of the ends of the fully tensioned spokes. I've compared Spokecalc calculations to the values computed by the DT spoke length calculator and to values calculated discretely from the equations in Brandt's book. They are the same in all three cases. According to Brandt, spokes can stretch about 1mm when tensioned and the rim diameter can shrink by as much as 2 mm (1 mm in radius). So, a gross estimate is that the length of the spoke needs to be about 1mm to 2mm shorter than the length calculated if you determine ERD by measuring a real untensioned rim. The DT spoke length calculator, as I recall, suggests a spoke length which seems to be the calculated value rounded down to the next integer.

You can see that an important question is where the ERD value that you are using comes from. If you are careful, you can measure the diameter of the rim pretty accurately with a couple of steel rulers. Or, you can position a couple spokes in opposite spoke holes, thread them up to nipples the way you want them to be when tensioned, and carefully mark the spoke overlap at the center. Then, disassemble the spokes, position the marks, and measure. Check several sets of spoke holes in case the untensioned rim is not perfectly round. I've checked a bunch of rims in the last several months and compared the values that I come up with to the values in the spokecalc database and they seem to be relatively close. Note that the values in the database for various rims have different sources and sometimes I have found different values in the database compared to internet sales site listings and even manufacturers sites, when available. Anyway, the best thing to do is to measure as accurately as you can the diameter of the spoke end circle that you want and then estimate the combined effect of spoke stretch and rim shrinkage and compare that to the spokecalc database or to values published elsewhere. They should be close to the same. If they're not, measure it again and then go with the value that you measure. And then, measure it again.

Now, whether or not the spokes that you have will work is another question. Figure out where you want the spoke ends and measure and calculate based on your measurement/estimation. If the spokes are longer than that, take a spoke and a nipple and see how much you can overthread the nipple before bottoming out. I would think that you would want to have 2 - 4 mm of excess nipple threadability, but that's your judgement.

Just for reference, the Sheldon Brown site says that Sheldon would calculate a spoke length and then round up to the nearest available length which could be more than 1mm for spokes that only come in 2mm increments. So, it's likely typical to be able to handle spoke lengths a little off from the ideal.

I've ordered all my custom length spokes from Colorado Cyclist and have checked the length on every order and they have always been 100% on the money. They charge $0.50 for 14 gauge DT and $0.90 for 14/15/14 gauge DT. Includes standard nipples -- 12mm brass, I think. Perhaps your supplier will exchange just the nipples for 10mm nipples, if possible? As Mr. Rabbit suggests.

But to address your concerns directly -- my wag is that your spokes will be fine, but I think you should verify it. Once the wheels are built, you shouldn't have to significantly retension the spokes. Maybe a little when you gas up your tires to full pressure which can compress the rim a little and maybe a little tweaking after a while, but not much.

operator

1mm too long?

Is that 1mm rounded up from an odd length? If so then it'll work just fine, on double walled rims. If it's 2mm+ then it is much too long. Clark, you'd really benefit from a good local shop, and stop trying to be a cheapskate on ****. Seriously.

mrrabbit 

Clark...if you used SpokeCalcs 604mm ERD which is directly copied from Mavic - then you are effectively aiming for the screwdriver flat of the nipple - or one thread past. It's a good mm to the top of the nipple from there.

As Operator and I have already touched upon - if using double wall rims and liberal 10mm nipples - you can probably get by. This assumes of course also that you aren't using for example 15g spokes in hub holes drilled for 13g spokes. It helps too that you rounded down when ordering...

=8-)

ClarkinHawaii

Is not being cheapskate--Is called "hobby"--no cheapskate would build wheel from scratch (at retail component prices) when ready-made wheels cost less than components. Is labor of love!

ClarkinHawaii

Without a doubt, this is the most helpful and most comprehensive reply I can remember ever receiving--or reading on this forum for that matter. It is a classic--I am so impressed! Thank you!

ClarkinHawaii

Hey, all you guys who responded--you all helped and i appreciate it. I just had to gush a bit at descon because his reply was, well . . . uniquely useful. Covered all the bases, including ones i hadn't thought of yet. Must have taken a long time and a lot of effort to prepare.

BikeWise1

So, where are you measuring from? Just curious. If you were inadvertently measuring total length of the spoke rather than from the inside of the "J" to the end of the threads, that might well account for the extra 1-1.5mm....

Just a thought.

ClarkinHawaii

That's a good question--I wondered the same thing. I am using a park Tool Spoke Ruler. The way it works. it's got little teardrop holes at one end. You stand the ruler on end, hang the spoke from the reardrop hole, and read where the threaded end lands on the scale.

desconhecido 

Spoke length is measured from the inside of the J at the spoke head to the end of the spoke.

Here is a link that should open the DT pdf file which shows this:

https://www.dtswiss.com/getdoc/71f384...Datasheet.aspx

miamijim

Thats the first thing that crossed mt mind when the OP mentioned had a spoke ruler. Lets hope he doesnt have a spoke tension gauge.

SBinNYC

The real problem is the lack of uniformity in length. A critical step after lacing the spokes is to tighten the nipples to the same distance from the end of the spoke. You may use a tool, make a tool or eyeball it, to make sure all the nipples are tightened the same amount. If you do this with "perfect" rims and hubs, then the wheel will be true. Starting with a laced up wheel that is true, makes for a very easy build.

Spoke threading is 56 tpi. That means a 1 mm difference in length translates to 2 complete nipple turns. As one adds tension to a wheel, do individual random spokes that are off by 2 turns make a difference. You bet they do.

ClarkinHawaii

Thanks, Guys--

It's pretty hard to screw up with the Park spoke ruler--you hang the spoke through the hole in the end and it automatically slides to the correct place in the J bend.

ClarkinHawaii

Well, 3 days and 3 emails later and no response from these people. They don't show a phone # on their site. This is IcyclesUSA.com. Spokes were $.48 each. Best price I could find with reasonable shipping charge. Sure glad I have other bike to ride.

Oh boy, I just did a site search for IcyclesUSA and all I see is "Beware" notices from previous screwees. Wonderful.