utoner34

I need some help selecting correct spoke lenght for the new wheel.

I have this rim:¨ 700c : https://www.dtswiss.com/en/component...d/gravel/g-540

and this hub: 28H 12x100 TA : D791SB | N guide

I would use spokes: dt alpine 3
and nipples: pro lock brass 2.0 12 or 14mm

My current wheel is 3 cross and I want this spoke pattern to stay.

Can you suggest what spoke lenght I need using this calculator? (or some other)

https://spokes-calculator.dtswiss.com/en/calculator

grumpus

By my reckoning (using that calculator, which I have no experience with) you want 291 mm both sides (calculator said 292.5 on the RHS but recommended 291).
But I'd normally build 28h as 2x - with 3x you may have less than ideal spoke/flange interaction on the larger flange. Calculator says 279/281 for 2x.
And I'd never trust someone else to tell me what spokes I need (except the supplier, in which case you can return them if they're wrong).
You could do 2x LHS and 3x RHS, just for fun.

Lombard

Important note. Take your own measurements for ERD. DO NOT trust the ERD published by the rim manufacturer. I have found more than one instance where the published ERD was wrong.

wheelreason

306, Phil Wood, and a little elbow grease.

FBinNY 

28h 3x pattern is full tangent. So flange diameter doesn't matter, and you can calculate spoke length in your head----almost.

MEASURE rim diameter to the tops of nipples. (I prefer to measure outside diameter, less the drop to the top of the nipple) divide by 2 for radius. Subtract 1mm.

Measure center to flange.

Now, use the Pythagorean Theorem. Square both and add. ie. 300mm, 40mm, ==== 90,000 + 1600 = 91600.

Use Google to find the square root and you're done, ie. Sq.rt. 91600 = 302.65mm
Round to nearest available length.

Note, there are minor fudge factors, which pretty much cancel out. I used this method very reliably for decades before online spoke calculators, and still use it as a cross check to all calculations. Non tangent wheels need another step, but aren't any harder.

FWIW I've always wondered if the easy math might have been one reason 36h 4x was so popular for decades.

utoner34

This is with 12 or 14 mm nipples?

utoner34

This is my bike. This is 3x if I am not mistaken?

https://archiv.cube.eu/_next/image?u...g&w=2048&q=100

https://archiv.cube.eu/en/2021/480100

BTinNYC 

Can't tell for sure from the pic, but I think it's 2x as it should be for a 28 hole rim. Count the times one spoke crosses the other spokes, even if it crosses behind the hub flange.

SurferRosa

You will need a $3 digital caliper to measure ERD. Park tool's site shows you how with clear and simple direction:

https://www.parktool.com/en-us/blog/...e-rim-diameter

This site shows you how to measure your hub with a $3 metric ruler with clear and simple direction:

https://leonard.io/edd/howtomeasure

Plug your results into a free calculator like this one and round down:

https://leonard.io/edd/

Jicafold

I have had good luck using this one:

ProWheel Builder Spoke Calculator

grumpus

Not easy to tell in those images which side the spokes are, but I think they're only crossing once next to the hub flange and once near the edge of the brake rotor, so 2X.

grumpus

I think I used 12 mm, but I'm failing to see why spoke length would be any different with 14 mm.

utoner34

I see 3x : https://imgur.com/a/dW5bxO8

sorry for not having better pictures, but I am on the road currently.

BTinNYC 

3x,yup!

FBinNY 

Most definitely 3x in the photo.

You don't have to count the crosses. You can tell by the angle the spoke leaves the hub.

2x 20, 3x 28, and 4x 36 are fully tangent.

utoner34

Why nipple length does not change spoke size?

FBinNY 

Because, regardless of nipple length, the spoke should reach well inti the nipple's head, which is always in the same place.

KCT1986

It depends on whether the longer nipples also has a little more thread added to the hub side of the nipple. This could cause the nipple to bottom out sooner if the spokes are too long. Usually if you have good rim and hub measurements used in a good spoke calculator it is not an issue.

DT nipples are said to have added threads for longer nipples.

See below.

FBinNY 

Yes, and no. Yes, longer nipple threads reduce the maximum height of the spoke. But no, because spokes still need to reach into the nipple's head.

Engagement into the nipple's head is the paramount consideration, and any spoke n that doesn't is too short.

Most experienced builders consider a spoke ending about 1mm shy of the top, or up to the slot as ideal.

IMO, Nipple thread length is more about tolerance and latitude in spoke length, rather than spoke length per se. If, for example, a spoke and nipple both have 10mm of thread, the spoke can reach ONLY to the top and not beyond. That makes spoke length critical since there's only 2mm between too long and too short. OTOH if the nipple has only 8mm of thread, the spoke can overrun the top by 2mm, allowing a 4mm range in spoke length. (Assumes a hollow rim where overrun isn't an issue).

So, it's not the nipple's length that should matter, but it's thread length, and only that.

utoner34

Does this mean if you use 14 mm nipples (instead of 12 mm) you can use shorter spokes or not?

FBinNY 

This was your original question and was answered a number of times.

A short answer --- NO --- was offered in post 17, along with the basic reason. Since you are the OP one might have hoped that you'd follow the thread.

Lombard

No, because you still want the spoke to go all the way into the nipple head for strength.

KCT1986

The best would be to not change the length of the spoke. Although on the DT calculator, it shows an -1mm adj for 14mm nipples & -2mm for 16mm, these adjustments would mean that the spokes won't go quite to the intended length into the nipple head. With brass nipples, 1mm short is probably OK for most applications, assuming the ERD is measured to the bottom of the slot or so.

With a new build, just use the actual calculated length and round up/down properly. With 14mm or longer nipples, the caution is that going too long may cause the nipples to 'bottom out'. Unless the rim calls for it, (unusually thick nipple seat, washers,..), longer nipples are not needed.

As stated in my prior post, the correct hub measurements, and proper information of the ERD (including point where it was measured to) should give you the proper spoke length.

FBinNY 

Just in case you still don't have it, here's a complete, (hopefully) clear answer using the sketch you referenced.

As a practical matter, let's assume that the target spoke length is somewhere between the top of the nipple and the bottom of the slot. Since that's ALWAYS true, the nipple length doesn't matter, and we can say that spoke length is determined by the height from the top. In the example, you'd have a working tolerance of about 2mm from the top of the nipple to slightly below the bottom of the slot.

On double walls you can go beyond the top of the nipple, limited by the nipple's thread length. If, for example the nipple has the same 10mm thread length as the spoke, you'll run out of thread when the nipple reaches the top. This means you cannot overrun the top keeping the working tolerance limited to that 2mm. OTOH, if the nipple only has 7mm thread length (regardless of the nipple's overall length) you can thread the spoke up to 3mm beyond the top. This is a serious advantage because it gives you an extra 3mm upside room increasing the total tolerance to 5mm. That allows you to err to the high side when choosing spokes and plan for the spoke to end at or beyond the top, ensuring that you'll be OK even if the calculation is off a bit.

Short answer, Minimum spoke length is based on top of the nipple, Maximum spoke length is determined by thread length (and/or the top of the nipple for single wall rims). Any length between these is equally OK.

FWIW- I very carefully select and buy nipples with 7-8mm thread length allowing me to safely add 1-2mm to most of the results generated by spoke calculators.